The Ultimate Guide: Houseplant Humidity
Indoor Plant Humidity Menu
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SCIENCE OF HUMIDITY
PHOTOSYNTHESIS
HUMIDITY PEST CONTROL
HIGH & LOW HUMIDITY PLANTS
HUMIDITY OVERVIEW
What Is Humidity?
Humidity may seem like a complicated subject if you've never learned what it is, but it's actually quite simple to understand. It's well worth the effort of demystifying humidity, as it can be a valuable weapon in your plant care arsenal to help solve numerous plant issues. Humidity helps to promote fast growth, and can be used to fix many plant woes, like slow growth, deformed growth, curly leaves, crispy leaves, or browning leaf tips commonly seen in sensitive species like Spider Plants. Humidity can help plants to produce their mature colours, or fenestrations, like seen in some Aroids, like Monstera.
How Humidity Impacts Houseplants: Humidity is a measure of the amount of moisture present in the air. It plays a crucial role in the overall health of houseplants, influencing everything from their growth rate to the vibrancy of their leaves. In simple terms, humidity measures the concentration of water vapour in the atmosphere. This moisture is vital for plants as it impacts their ability to absorb water through their leaves, contributing to essential physiological processes that help them grow.
How We Sense Humidity Changes: Humidity refers to how wet or dry the air is, which we can sometimes sense with our noses as we breathe. You can notice this yourself by opening the door into a steamy bathroom—this represents a wet, humid environment. Conversely, stepping off a plane or getting out of an air-conditioned car into a hot, dry area exemplifies how low humidity feels to us. Have you ever stood outside and thought that it was about to rain? That's usually because your nose can sense the higher humidity levels, signalling a change in the weather. Humidity can only typically be sensed at the extremes by humans, but plants, however, are very particular about their humidity needs.
Humidity Issues In Houseplants: Low humidity levels can cause the soil to dry out faster and the plant to lose more water through its leaves, leading to issues like wilting, browning leaf tips, and stunted growth. Excessively high humidity can create a breeding ground for mould and mildew, potentially harming the plant. This is one reason why we always recommend misting plants at night, as excess moisture can lead to fungal infections. We'll dive into these subjects in much more detail later on. It's important to note that both extremes of humidity cause their own issues, and the key to achieving good plant growth indoors is finding the balance of humidity levels for each plant species.
The Science Behind Humidity: While it may seem like a straightforward concept, humidity's effect on plants involves fascinating scientific principles, including transpiration and the maintenance of turgor pressure, which are critical for keeping plants upright and hydrated. Humidity can also play a role in helping plants achieve their maximum growth potential, with mature forms of leaves like fenestrations, mature variegations, or colourations. Understanding the right humidity levels for your houseplants is essential for creating an optimal indoor environment that supports their growth and well-being. Let's dive deep into the world of houseplant humidity to help you achieve maximum plant growth indoors, with plants that thrive rather than just survive.
The Benefits Of Humidity For Indoor Plants
Humidity is more than just a measure of moisture in the air; it's a key factor that significantly influences the health, growth, maturity, and vitality of indoor plants. By understanding the benefits of maintaining proper humidity levels, you can create an optimal environment that promotes the well-being of your houseplants. Let's explore the ways that humidity can benefit houseplants when used to your advantage:
Fast Growth and Plant Maturity
Plants that are provided with the right humidity levels tend to grow faster and more robustly. The added moisture in the air supports key physiological processes like photosynthesis and transpiration, leading to more vigorous growth and fuller, more attractive plants. Humidity can also aid in the development of mature leaves, affecting their colours, sizes, and leaf splits and holes. For instance, humidity is crucial for plants to produce fenestrated leaves. Some species, like the Alocasia robusta, which can reach leaf sizes of 12 feet (3.66 meters) in the wild, require the right humidity levels to produce these massive mature leaves. Understanding and being able to influence the humidity levels for your houseplants can play a vital role in plant maturity.
Improved Leaf Quality
Humidity can enhance the aesthetic quality of your plants by reducing issues like deformed new growth, curly leaves, crispy tips, and more. Many houseplants, such as ferns and tropical species, develop larger, healthier leaves in humid conditions. This not only improves the overall appearance of the plant but also increases its ability to photosynthesize effectively. Higher humidity levels can help leaves to unfurl without becoming stuck in the leaf sheath, which is a common problem in some plants like Scindapsus and Philodendrons. Inadequate humidity can cause leaves to become stuck, leading to tears or breaks. Higher humidity levels can resolve this issue by ensuring the air is sufficiently moist to lubricate the leaves. A great tip for stuck leaves is to wrap a damp paper towel or cloth around the stuck leaf for 15–20 minutes.
Reduces Browning Leaf Tips
Higher humidity levels can help reduce the occurrence of browning leaf tips, commonly seen in sensitive plant species like Spider Plants, Prayer Plants, and some Alocasia varieties. To prevent brown tips on leaves, try increasing the humidity around your plants. It's important to note that while leaf tips can brown due to a lack of humidity, other factors like chlorine or chloramine in tap water can also cause this issue. Using a dechlorinator and room temperature water for sensitive plants can help to prevent damage, as cold water can shock roots and damage cells. We personally use Ecothrive dechlorinator, as we've had great results using their product for our nursery plants. Here's a link to their products: Ecothrive Neutralise: 1L/£50, 250ml/£20, and 50ml/£10.
Improved Water Absorption
Plants primarily absorb water through their roots, but they can also take in moisture through their leaves. This evolutionary feature is frequently harnessed by plant keepers by using foliar feeds to deliver nutrition to the plant's active growth points, or through misting to hydrate the leaves. Providing your houseplants with the correct humidity levels helps them to maintain hydration more efficiently, reducing the energy needed to transport the water from the roots to the active growth points, like new leaves and stems.
Maintaining the correct humidity for your houseplants helps to prevent excessive water loss through transpiration. High humidity facilitates the absorption of water through plant leaves, supporting something called turgor pressure within the plant. Turgor pressure is the force within plant cells that keeps them firm and supports overall plant structure and health. Proper humidity levels contribute to optimal turgor pressure and overall plant health, promoting vigorous growth and reducing plant stress.
Disease Prevention
Certain plant diseases thrive in dry or overly moist conditions. For example, an Agave thrives in a dry, arid desert, while a Philodendron thrives in a humid tropical environment. Proper humidity levels for different plant species help create a balanced environment that reduces the risk of fungal infections, mould, and pests. Maintaining moderate humidity levels can help to prevent the development of powdery mildew and other common plant diseases, while high humidity can reduce pests by making the environment inhospitable for them. Sealing pest-ridden plants in plastic bags to increase humidity is a common practice because some pests, like thrips and aphids, cannot survive high humidity levels. We've written about fighting pests with humidity in more detail later in this article.
Enhanced Nutrient Uptake
Humidity plays a vital role in the transport of nutrients within the plant. When humidity levels are optimal, plants can more efficiently move water and dissolved nutrients from the roots to the leaves, ensuring the houseplants receive all necessary elements for growth without expending excessive energy. This leads to healthier houseplants with more vibrant foliage.
Reduced Plant Stress
Maintaining the appropriate humidity levels for individual houseplant species can significantly reduce houseplant stress. Low humidity can cause water stress, leading to wilting, browning leaf tips, and stunted growth. High humidity, on the other hand, can cause mould and mildew problems. Keeping humidity within the ideal range for each houseplant species minimizes stress factors, allowing your plants to thrive rather than just survive.
Houseplant Humidity Solutions: Ways to Increase Humidity
Maintaining the right humidity levels for your houseplants can sometimes be challenging, especially in dry indoor environments. Fortunately, there are several simple and effective methods to increase humidity around your plants, ensuring they receive the moisture they need to thrive. We've listed the most effective ways to increase humidity, from free DIY methods to electronic humidifiers that can precisely control the environment around your houseplants. Let's explore the different ways to increase humidity for indoor plants:
Misting Houseplants To Increase Humidity
Benefits: Misting is a quick and easy way to temporarily increase humidity around your plants. It’s a simple and affordable technique that helps replicate the natural moist air found in their native environments.
How To: Use a spray bottle with an adjustable spray head to lightly mist your plants' leaves. A pressure spray bottle is preferred for even application and the ability to work upside down. Mist in the evening after the sun has gone down or after grow lights have been turned off. This allows the foliage to dry throughout the dark period, reducing the risk of fungal growth. Misting during the day can create a lens effect with sunlight, potentially burning the plant leaves. Avoid over-misting, which can lead to waterlogged soil and potential root rot.
Cost: A good quality sprayer usually costs under £4, and a pressure sprayer is around £10-15 depending on the season.
Using Pebble Trays & Bowls To Raise Humidity
Benefits: Placing bowls of water with pebbles around your plants can help increase local humidity through evaporation. Humidity trays are a free and effective way to provide a consistent source of humidity as the water in the tray evaporates. This method is especially helpful during propagation to encourage hydration before roots have developed.
How To: Fill bowls with water. You can use various containers like bowls, oven dishes, vases, saucers, or glass jars. Place these bowls around your plants, ensuring they are not directly in contact with the soil. Refill the bowls with water as needed.
Cost: Free—any household should be able to find suitable containers for this method in their kitchen cupboards.
Alternative Method with Secondary Benefits:
Another technique is to use trays filled with water and pebbles that sit directly beneath the plant pot instead of a water tray. This increases humidity directly around the plant. To use this method, fill a tray with water and add enough pebbles or small stones to ensure that the water level is below the stones. Place the plant pot on top of the pebbles, ensuring that the bottom of the pot is above the water level. Refill the tray with water as needed to maintain humidity, ensuring that the soil never touches the water. Add more stones if the plant pot is getting wet.
How Humidity Trays Help Plant Growth:
You may find that your plant starts to grow roots into the pebble tray, utilizing the additional moisture. These roots are called hydro roots and are specially adapted to grow and thrive in water. Hydro roots can help the plant grow faster by providing a consistent source of moisture, reducing the likelihood of root rot since these roots are specifically grown for hydroponic conditions. If your plant grows roots into the humidity tray, there’s no need to worry—it’s actually very beneficial for most houseplants. Hydro roots are more efficient at absorbing oxygen and nutrients directly from water, aiding in plant health and growth by providing constant moisture, with less chance of root rot.
Using Humidifiers For Houseplants
Benefits: If you want a more precise and consistent humidity level around your houseplants, an electronic humidifier may be the best option. There are several types of setups for humidifiers, ranging from affordable USB models to more expensive, advanced humidifiers with humidistats that ensure they only turn on when needed. If your budget allows, we always recommend choosing a humidifier with a humidity sensor to prevent moisture levels from getting too high and causing plant health issues. For those with large houseplant collections, electric humidifiers can be the most effective way to maintain humidity over larger areas. We've compiled a list of our favourite humidifiers to help you choose the right one for your houseplants, but for now, let's explore how to use them:
How To: Select a cool mist or ultrasonic humidifier for the best results. Both affordable and advanced setups available. See our list of recommended humidifiers. Place the humidifier near your plants, but do not let the mist directly touch them. When the fog from a humidifier hits plant leaves, it allows excessive moisture to build-up, which could lead to fungal issues or mould growth. Run the humidifier during the day to maintain optimal humidity levels. Use a hygrometer to measure the humidity levels around your plants and adjust the use of the humidifier as needed. For precise control for individual houseplant species, use one with a humidistat function to allow the humidifier to only turn on when required and to turn off when the humidity levels have reached the desired amount.
Cost: Anywhere from £15 to £150 depending on the tech level required. Check our recommended list of houseplant humidifiers for prices.
Grouping Plants Together To Raise Humidity
Benefits: This technique is constantly used at our houseplant nursery to provide localized humidity to our plants. It’s free, easy, and allows the plants to do some of the hard work for you. We highly recommend this method to manage humidity, as we've had great success using it to keep huge numbers of plants in the correct humidity levels. We also find it incredibly useful when managing individual species that require higher humidity levels. This is one of the biggest trade secrets from our houseplant nursery, as it allows us to keep the correct humidity levels for large numbers of plants without the maintenance of refilling numerous machines every day. Grouping plants helps to create a microenvironment where the combined transpiration from multiple plants naturally raises the humidity levels. This is especially effective when combined with a humidifier or when using water evaporation to raise humidity locally. Let's explore how to group plants to raise humidity:
How To: Arrange your plants close together in clusters. This not only looks nice, but also serves the practical purpose of helping to raise humidity for the plants. Consider placing the group of plants in a naturally humid area of your home, such as a bathroom or kitchen, which will help humidity further than just grouping plants together alone. Monitor the plants for any signs of pests or diseases that can spread more easily amongst plants. If you suspect issues, don’t move the grouped plants around, as this could spread any problems to other plants in your collection. Keeping plants in groups allows you to easily quarantine and treat sections of your houseplant collection. When treating a grouped plant, we recommend treating the entire group, even if the plants don’t all show symptoms. Pests can lay eggs in or around healthy plants even when there are no visible signs of an infestation, and diseases can spread without noticeable symptoms, so it’s always best practice to treat the entire group.
Cost: Free
Using Domes, Cloches, Or Plastic Bags To Increase Humidity
Benefits: Plant domes or cloches create a mini greenhouse effect, trapping moisture and increasing humidity around the plant. We use this method regularly at our houseplant nursery during propagation, as it allows cuttings to absorb moisture through their leaves before their new roots have formed. This encourages faster propagation and reduces the chances of pest issues on vulnerable, stressed cuttings. When taking cuttings, a propagator with a lid or a plastic box can be invaluable to encourage faster rooting. It's quite common for some high humidity loving species, like Frittonia (pictured), to be kept in terrariums or indoor greenhouses, as it eliminates issues with low humidity. Let's explore how domes, cloches, or mini greenhouses can help maintain humidity for houseplants:
How To: Place a clear plastic or glass dome over the plant to create a humid microenvironment. This helps trap moisture inside, keeping the humidity levels higher than in the ambient air in your home. Remove the dome periodically to allow for air exchange and prevent mould growth. Use domes primarily for small plants or seedlings that require higher humidity.
Cost: Ranging from £5 to £35
Alternative Method: You can use a large plastic bag to seal plants to raise humidity. To use this method, grab a large resealable food bag and place the plant inside. Seal the bag, ensuring that it is full of air and fully expanded. Monitor plants closely, and exchange the air at least once a day by opening the bag to prevent fungal issues or mould growth. If you see any problems, you can pierce the bag to provide extra ventilation for the plant.
Other Techniques to Increase Humidity for Houseplants
Creating a Humidity Tent: A humidity tent is an effective way to create a high-humidity environment for plants that require significant moisture levels. Use clear plastic bag to create a tent over the plant. Drape the plastic over the plant and secure it at the base, leaving enough space for air circulation. Remove the tent periodically to allow for air exchange and prevent mould. We recommend exchanging the air in the tent once a day, as we've found it helps to reduce fungal issues often seen with high humidity levels.
Using an Indoor Water Feature: While this method is effective for smaller areas, it may not be practical or affordable for everyone, and it may result in you needing more frequent trips to the bathroom! Adding a small indoor water feature, like a fountain, can help to increase humidity levels in a room. The moving water continuously evaporates, adding moisture to the air. Position the water feature near your plants, but ensure it’s in a safe location where it won’t spill or damage furniture. Keep the water feature clean and ensure it has a steady supply of water.
Room Temperature: Although it may seem trivial, the temperature within your house can influence humidity levels. Maintaining a stable room temperature helps manage houseplant humidity levels. Sudden temperature changes can affect the air’s moisture content. Use heating, fans, or electric heaters as needed to keep the temperature consistent, and monitor results with a thermometer that records a 24-hour average to allow you to adjust nighttime temperatures as needed.
Keeping Plants in Wet Rooms: Rooms that are naturally more humid due to regular water use, such as bathrooms and kitchens, can help maintain higher humidity levels. Consider placing humidity-loving houseplants in these areas to allow them to naturally benefit from the higher moisture levels. This is a commonly deployed tactic to aid indoor plant growth without having to adjust humidity levels.
The Best Humidifiers For Houseplants
Finding a humidifier suitable for your houseplants, and your budget, can be a hard task. To help you manage your humidity, we've listed our favourite humidifiers that we'd recommend for indoor plants, together with how much they cost, and how much water they can hold. Let's have a look at the best humidifiers for houseplants:
LEVOIT 2.5L Humidifier — £35 on Amazon
Homvana 3.6L Humidifier — £34 on Amazon
Vicks Mini Cool Mist 1.8L — £44 on Amazon
Bear 5L Humidifier — £34 on Amazon
Generic 500ml Humidifier — £15 on Amazon
GoveeLife 3L Humidifier — £40 on Amazon
Seasonal Changes and Their Impact on Indoor Humidity Levels
Seasonal changes can significantly impact the humidity levels in your home. When humidity levels drop, the health and growth of your houseplants can be affected, leading to slower plant growth. Understanding these variations throughout the seasons and how to manage the changes is crucial for maintaining optimal humidity levels for houseplant growth indoors. Let's explore how the seasons impact humidity levels for indoor plants:
Humidity Adjustments During the Winter
During the winter, indoor humidity levels often drop due to the use of indoor heating systems. Dry interior air can be particularly challenging for houseplants, especially those from tropical environments. Low humidity can lead to issues like wilting, browning leaf tips, and increased susceptibility to pests. To raise local humidity for your houseplants, refer to our guide on managing humidity, which lists a range of free, affordable, and high-tech options.
Spring and Summer Humidity Adjustments
In spring and summer, humidity levels generally rise due to increased outdoor moisture and warmer temperatures. Most houseplants thrive during these seasons as the conditions mimic their natural habitats. Ensure good air circulation to prevent mould and mildew growth. Use fans if necessary. Monitor your plants closely, as they may require more frequent watering. However, avoid overwatering as this can lead to root rot.
Autumn Humidity Adjustments
Autumn can bring fluctuating humidity levels as temperatures drop and heating systems start to come back on. This transition period requires careful monitoring of your indoor environment. Autumn is usually the season when most plant keepers start using humidifiers or techniques like trays, misting, or grouping plants to maintain consistent humidity levels. Clean any humidifiers and fans regularly to ensure they operate efficiently and don’t harbour mould or bacteria. For more information on maintaining adequate humidity, refer to our guide on increasing humidity, which lists a range of free, affordable, and high-tech options.
Tips for Year-Round Humidity Management
Regular Monitoring: Hygrometers can help you make informed decisions about when to use a humidifier or other humidity-boosting methods. At our houseplant nursery, we prefer to use hygrometers with 24-hour memory functions to allow us to closely monitor the averages over the day and night. We highly recommend using a hygrometer thermometer combination with a memory to record data like the one we've linked, as it allows you to see when humidity drops, and to figure out how to prevent it from recurring. Monitoring the temperature alongside the humidity helps you adjust as needed to prevent fluctuations.
Flexible Solutions: Be prepared to adjust your humidity management techniques according to the seasonal changes. Having a variety of tools and methods at your disposal can help you respond effectively to fluctuations in humidity. Quick, easy, and free options like humidity bowls or trays can be incredibly helpful to make fast changes to humidity levels around houseplants.
Plant Placement: Consider relocating your plants based on seasonal humidity changes. For example, moving humidity-loving plants to a naturally more humid area like a bathroom during dry months can help maintain their health. Also, consider grouping plants together to raise humidity around them.
Optimal Humidity Levels for Common Houseplants: A Comprehensive Guide
Different houseplants have unique humidity requirements, and understanding these needs is essential for their health and growth. This section provides a detailed look at the optimal humidity levels for some of the most popular houseplants. By keeping your plants within their natural ranges, you ensure healthier growth, and fewer chances of fungal infections. To see the individual humidity requirements for each houseplant species, check our A-Z encyclopedia of plant care. Let's explore some of the most common plants and what humidity levels they prefer:
Common Houseplants and Their Humidity Needs
Spider Plant (Chlorophytum comosum): Spider plants thrive in moderate humidity. Misting occasionally can help in dry indoor environments. Optimal Humidity: 40-60%
Peace Lily (Spathiphyllum): Peace lilies prefer higher humidity levels. Consider regular misting and placing the plant on a humidity tray. Optimal Humidity: 60-80%
Boston Fern (Nephrolepis exaltata): Boston ferns require consistently high humidity. Use a humidifier or place them in a naturally humid area. Optimal Humidity: 50-80%
Orchids (Various genera): Orchids thrive in moderately high humidity. Ensure good air circulation to prevent mould and mildew. Optimal Humidity: 50-70%
Snake Plant (Dracaena trifasciata, reclassified from Sansevieria in 2018): Snake plants are tolerant of lower humidity levels. Optimal Humidity: 30-50%
Fiddle Leaf Fig (Ficus lyrata): Fiddle leaf figs prefer moderate humidity. Misting and using a humidity tray or bowl can help maintain ideal conditions. Optimal Humidity: 40-60%
Aloe Vera (Aloe barbadensis miller): Aloe vera plants thrive in low to moderate humidity. They are well-suited for dry indoor environments. Optimal Humidity: 30-50%
Adjusting Humidity Levels For Individual Houseplant Species
Check the humidity requirements of different houseplant species before making changes. Maintaining the right humidity levels for different houseplants can be achieved through various methods that we've covered throughout this humidity guide. To recap, here are some effective techniques to increase humidity for indoor plants, and links to detailed guides for each method:
Misting: Regularly misting your plants can provide temporary humidity boosts. Be cautious not to over-mist, which can lead to mould growth.
Humidity Trays: Placing plants on trays filled with water and pebbles can help increase local humidity as the water evaporates, as does placing bowls of water nearby.
Grouping Plants: Grouping houseplants together can create a microenvironment with higher humidity, as plants release moisture into the air through transpiration.
Humidifiers: Using a room humidifier is an effective way to maintain consistent humidity levels, especially during dry winter months.
Placement: Placing plants in naturally humid areas, such as bathrooms or kitchens, can help meet their humidity needs.
Signs of Humidity Stress in Houseplants and How to Address Them
As you have learned throughout this article, humidity plays a vital role in the health of your houseplants. Learning how to manipulate and control humidity can be an invaluable tool in any plant care arsenal. To effectively utilize humidity for houseplant growth, it's important to be able to recognize the signs of humidity stress when monitoring changes. Both low and high humidity levels can cause various stress symptoms that impact plant growth and appearance. Recognizing these signs early and taking appropriate action can help keep your plants thriving. Let's explore the signs to watch out for, and how to fix humidity issues in houseplants:
Signs of Low Humidity Stress
Wilting and Drooping: One of the first signs of low humidity stress is wilting or drooping leaves. This occurs because the plant loses water faster than it can absorb from the soil, causing it to lose turgor pressure. Wilted plants have leaves that lose their ability to stand up, drooping down and hanging off the stems. Some species can lose pressure in their stems when suffering from low humidity, causing them to bend and sometimes snap. This is often seen in long stem plants, like Alocasia or Colocasia, whose stems become fragile when they lose turgor pressure, leading to breakages and lost leaves.
Browning Leaf Tips: Low humidity can lead to brown, crispy tips on the leaves, indicating that the plant is losing moisture too quickly. This is typically seen in plants like Spider Plants, Prayer Plants, or Alocasia. It's important to note that this can also be caused by chlorine or chloramine in tap water, and using a dechlorinator can help prevent crispy brown leaf tips, like seen in the photograph we've included to illustrate.
Leaf Drop: When a plant is stressed by low humidity, it may shed its leaves to conserve water. This is particularly common in plants that are not well-adapted to dry environments, like Aloe or Agave plants. While plants frequently shed lower leaves as they grow new ones, it is unusual for them to drop several leaves at once or to shed top leaves. This is a clear indication of stress, and humidity levels should be monitored and adjusted as needed for each houseplant species. The leaves may be brown or yellow, or a combination of both, with varying levels of green left on the leaf, as illustrated in the photographs we've included.
Stunted Growth: Low humidity can inhibit a plant’s ability to take up nutrients, leading to slowed or stunted growth. Plants may appear smaller and less vigorous than usual.
Signs of High Humidity Stress
Mold and Mildew: Excessively high humidity can create a favourable environment for mould and mildew to grow on the soil surface and plant leaves. This can lead to plant diseases and weakened health. Mildew and mould on the soil surface can appear as a white, fuzzy layer that sometimes looks furry or hairy.
Yellowing Leaves: High humidity levels can cause leaves to yellow and drop prematurely, often due to root rot from too much moisture in the soil. Reduce watering frequency and allow the plant to dry out thoroughly between watering. Yellow leaves can vary in appearance as shown in the photos we've included to illustrate.
Fungal Infections: High humidity promotes fungal growth, which can manifest as spots or patches on the leaves. This is particularly problematic in plants that prefer drier conditions. Some species are more susceptible to black spots on the leaves than others. Spots can also be caused by factors such as overwatering, bacterial infections, sunburn, nutrient deficiencies, or pest infestations. It can be challenging to distinguish the cause, so monitoring plant care routines is essential. Check individual species' care requirements and adjust as needed.
Sluggish Growth: While some plants thrive in high humidity, others may suffer from sluggish growth due to an imbalance in their moisture levels. This can lead to weak, leggy plants that require pruning. Always check plant species' humidity requirements before making adjustments to avoid plant care issues.
How to Address Humidity Stress
To Remedy Low Humidity Issues:
Increase Humidity: Use a humidifier to add moisture to the air, or place a humidity tray or bowl near your plants.
Group Plants Together: Grouping plants can create a microenvironment with higher humidity due to their collective transpiration.
Regular Misting: Mist plants with water to provide temporary humidity boosts.
Relocate Plants: Move your plants to more humid areas of your home, such as the bathroom or kitchen.
To Remedy High Humidity Issues:
Improve Air Circulation: Use fans to increase airflow around your plants, reducing the risk of fungal growth. We prefer to use Honeywell TurboForce Power fans.
Reduce Watering Frequency: Allow the soil to dry out slightly between watering to prevent excess moisture build-up.
Remove Affected Leaves: Prune any mouldy or infected leaves to prevent the spread of disease.
Use Dehumidifiers: In extremely humid environments, a dehumidifier can help balance the humidity levels. You can buy affordable electric ones, gel based units, or more expensive 30L large units.
Mould caused by high humidity
Yellowing Ficus leaf
Heald edema on Aglaonema leaf
Alocasia with brown leaf tips
Yellow wilting Monstera Albo leaf
Dropped brown & yellow leaves
Choosing Low Or High Humidity Plants
This topic naturally follows on from discussing humidity related stress, as the best way to avoid issues is to choose plants that are naturally suited to the humidity of your home, which avoids the need for monitoring and adjustment. Finding and selecting houseplants that prefer your indoor environment can make a significant difference in their health, and the ease of the plant's care. Some plants are more naturally suited to wet environments, like bathrooms and kitchens, whilst some plants are more suited to drier air.
We always recommend checking the humidity preferences of different plant species' before purchase if your goal is to reduce plant care. By picking houseplants that are naturally suited to the humidity levels in the different areas of your home, you can reduce the stress on your plants, and reduce the need for constant humidity adjustments or monitoring. Let's explore some houseplants that are suited to low and high humidity environments:
High Humidity Plants
Certain houseplants flourish in high humidity environments, often replicating their natural tropical habitats. Here are some of our favourite high humidity houseplants:
Boston Fern (Nephrolepis exaltata): Boston ferns require consistently high humidity. They are perfect for bathrooms or kitchens where humidity levels are naturally higher.
Peace Lily (Spathiphyllum): Peace lilies thrive in humid conditions. Regular misting and a humidity tray can help maintain the necessary moisture levels.
Orchids (Various genera): Orchids prefer moderate to high humidity. They do well in well-lit, humid areas and benefit from regular misting.
Calathea (Various species): Calatheas require high humidity to maintain their vibrant foliage. They are best kept in humid environments with regular misting.
Philodendrons (Various types): Philodendrons thrive in high humidity, making them perfect for wetter homes, kitchens, or bathrooms.
Low Humidity Plants
Some houseplants are naturally adapted to dry environments and can tolerate lower humidity levels without stress. Here are a few of our favourite low humidity houseplants:
Snake Plant (Dracaena trifasciata, reclassified from Sansevieria in 2018): Snake plants thrive in dry air. They require minimal care and low humidity.
Aloe Vera (Aloe barbadensis miller): Aloe vera prefers dry conditions and does well in low humidity environments. It’s a hardy plant that requires minimal watering.
ZZ Plant (Zamioculcas zamiifolia): ZZ plants are versatile and can tolerate a range of humidity levels, making them ideal for less humid homes.
Jade Plant (Crassula ovata): Jade plants thrive in dry air and require infrequent watering, making them suitable for low humidity conditions.
Agave Plant (Agave Americana): Agave plants thrive in dry conditions, making them suitable for low humidity rooms.
How Humidity Can Help To Control Pests in Houseplants
Humidity might not be the first thing that comes to mind when thinking about pest management for houseplants, but it can be a surprisingly effective tool. Controlling pest numbers in houseplants can be challenging, but leveraging humidity is an effective and natural strategy to help you get rid of houseplant pests. One particularly useful technique is creating a greenhouse environment by sealing the pest-infested plant in a plastic bag. This method significantly increases the humidity around the plant, creating conditions that can disrupt and control various pests. Often used in combination with other treatment methods, this approach can be highly effective in eradicating houseplant pests. Let's explore how humidity can help remove pests and why it's an effective part of pest management and prevention.
High Humidity's Impact on Pest Life Cycles
Spider Mites: Spider mites are notorious for thriving in dry conditions. These tiny arachnids feed on plant sap, causing discolouration and leaf drop. They can be one of the most frustrating houseplant pests to eliminate, causing significant losses and stress. High humidity levels disrupt their life cycles, reducing their reproductive success. By sealing a plant infested with spider mites in a plastic bag, you create a microenvironment that spider mites find inhospitable, effectively curbing their population. This method is particularly effective when combined with traditional spider mite control methods. For more detailed guidance, check out our comprehensive guide on how to remove spider mites.
Fungus Gnats: Fungus gnats are among the most annoying pests to infest your home, as they affect both you and your plants. You might find them in your drinks or buzzing around your food. Fungus gnats are attracted to moist soil, where they lay their eggs. While fungus gnat larvae can damage plant roots, managing their population through humidity control is possible and can be effective when combined with other treatments. Increasing the humidity around the infected plant (without watering the soil to avoid promoting gnat breeding) can help manage fungus gnats. Higher humidity supports the growth of beneficial microorganisms in the soil, which can outcompete and suppress fungus gnat larvae. For detailed information, read our guide on how to get rid of fungus gnats and prevent reinfestations.
Aphids: Aphids are another common pest that can cause significant damage by feeding on plant sap and spreading diseases. They can appear in large numbers, causing panic when first spotted. While high humidity alone may not completely eradicate aphids, it can slow down their reproduction and make the environment less favourable for their proliferation. This reduction in their reproductive rate can significantly diminish aphid infestations over time. If your plant is suffering from an aphid infestation, our full guide on how to get rid of aphids provides comprehensive information.
Thrips: Thrips are tiny insects that can be very hard to notice, causing damage to plants by feeding on their tissues. They resemble long black specks on plant leaves. Thrips prefer dry conditions, so increasing humidity around houseplants can hinder their development and reduce their population. The moist environment created by a plastic bag can disrupt the thrips' life cycle, making it difficult for them to thrive. For detailed guidance on dealing with thrip infestations, refer to our comprehensive thrip removal guide.
How Effective Is Humidity For Houseplant Pests?
While increasing humidity can be beneficial for controlling pests, it’s essential to monitor your plants closely. Excessive humidity can promote fungal growth, which could cause additional problems. To avoid additional stress while dealing with pests, monitor plants closely for any issues and adjust accordingly. You can pierce the plastic bag to create small ventilation holes if the environment becomes too humid. Ensure daily ventilation by briefly opening and closing the bag to exchange the air. Use this technique for short periods to mitigate any negative effects, but avoid prolonged exposure to high humidity levels, especially for houseplants that typically thrive in dry, arid conditions. Combining humidity control with other pest management strategies, such as regular inspection, physical removal, and using insecticidal soaps or oils, can enhance effectiveness. For a full guide on dealing with houseplant pests, see our pest removal article.
Turgor Pressure and Plant Hydration
Turgor pressure is the internal pressure exerted by water within the plant cells. It is vital for maintaining the plant's structure, keeping it upright, and facilitating growth. Adequate humidity levels help maintain turgor pressure by ensuring a steady supply of water to the plant cells. When humidity is too low, plants struggle to maintain this pressure, leading to wilting and other signs of stress. When long stem plants wilt due to insufficient turgor pressure, it's common for the stems to snap, causing leaf loss. This is commonly seen in species like Colocasia or Alocasia.
Photosynthesis and Humidity
Photosynthesis, the process by which plants convert light energy into chemical energy, is also affected by humidity. Adequate humidity ensures that the stomata remain open, allowing for the efficient exchange of gases—carbon dioxide in and oxygen out. If the air is too dry, the stomata may close to conserve water, thereby reducing the plant's ability to photosynthesize effectively. We explore the role of humidity in photosynthesis later on in this houseplant humidity guide.
Humidity's Role in Leaf Development
Humidity can significantly influence the morphological features of plants, such as leaf size, shape, and texture. For instance, certain houseplants, like Monstera, develop fenestrations (leaf holes) and intricate variegations more prominently in environments with higher humidity. Maintaining optimal humidity levels can enhance the health of the plant, promoting maturity.
Balancing Humidity Levels
Achieving the right balance of humidity is key to preventing common plant issues. Low humidity can lead to dry, crispy leaves, while excessive humidity can promote fungal growth and mould. Understanding the specific humidity requirements of your houseplants can help you create a thriving indoor garden.
The Science of Humidity: Understanding How It Affects Houseplants
Humidity, in the context of houseplant care, plays a fundamental role in maintaining plant health and promoting vigorous growth. To fully appreciate how humidity impacts houseplants, it's essential to delve into some scientific principles at play.
The Role of Transpiration
Transpiration is the process by which water is absorbed by plant roots, transported through the plant, and released as water vapour from the stomata—tiny pores on the leaf surfaces. This process is crucial for several reasons:
Nutrient Uptake: As water moves through the plant, it carries essential nutrients from the soil to various parts of the plant.
Cooling Mechanism: Transpiration helps regulate the plant's temperature, preventing overheating.
Maintaining Turgor Pressure: This internal pressure keeps the plant cells firm, providing structure and support.
Humidity levels directly influence the rate of transpiration. In low humidity environments, transpiration rates increase, leading to more rapid water loss. Conversely, high humidity can slow down transpiration, reducing the risk of dehydration, but potentially leading to excess moisture issues if not balanced properly.
The Role of Humidity in Photosynthesis and Plant Growth
Humidity plays a significant role in photosynthesis, the process by which plants convert light energy into chemical energy. This transformation is crucial for plant growth and development, as it produces the sugars necessary for sustaining life.
How Humidity Affects Photosynthesis
Stomatal Function:
Stomata are tiny openings on the surfaces of leaves that allow for gas exchange. They take in carbon dioxide (CO₂) from the air and release oxygen (O₂) as a by-product of photosynthesis. Proper humidity levels are essential for the optimal functioning of these stomata. In low humidity environments, plants may close their stomata to conserve water, which limits CO₂ intake and slows down photosynthesis. On the other hand, excessively high humidity can prevent the stomata from closing properly, leading to water retention issues and increased risk of fungal infections. Balancing the humidity and ensuring the correct levels are met for each plant species helps to prevent humidity related issues.
Water Vapour and Gas Exchange:
Humidity impacts the rate at which water vapour is released through transpiration. During transpiration, water evaporates from the plant's leaves, creating a negative pressure that pulls water and nutrients from the roots up through the plant. Adequate humidity ensures a balanced rate of transpiration, facilitating the transport of nutrients and maintaining healthy growth.
How Humidity Affects Plant Growth
Enhanced Growth:
When humidity levels are optimal, plants can efficiently photosynthesize, leading to robust growth and vibrant foliage. Proper humidity helps maintain turgor pressure, which supports the structural integrity of plant cells and encourages leaf and stem expansion.
Leaf Morphology:
Humidity can also influence the physical characteristics of leaves. In high humidity environments, plants may develop larger leaves with thinner cuticles to maximize water uptake. This adaptation helps the plant thrive in its specific environment. Conversely, in low humidity conditions, plants might develop thicker leaves to reduce water loss.
Stress Reduction:
Maintaining appropriate humidity levels reduces stress on plants. Stress from low humidity can result in wilting, leaf drop, and slowed growth, while high humidity can lead to mould, mildew, and other fungal issues. By keeping humidity levels within an ideal range, you can help ensure that your houseplants remain healthy and resilient.
Understanding the intricate relationship between humidity, photosynthesis, and plant growth allows you to create an environment where your houseplants can thrive. By managing humidity levels effectively, you can enhance their overall health and promote lush, vigorous growth.
An Overview Of Houseplant Humidity
Creating the ideal humidity levels for your houseplants is a vital aspect of plant care that can significantly impact their health and growth. By understanding the science of humidity, recognizing signs of humidity stress, and implementing effective solutions, you can ensure that your indoor garden thrives year-round.
Key Takeaways:
Understanding Humidity: Humidity is the measure of moisture in the air, and it plays a crucial role in plant health by affecting processes like transpiration, photosynthesis, and nutrient uptake.
Optimal Humidity Levels: Different houseplants have varying humidity needs. Knowing these requirements helps you provide the best conditions for each plant.
Signs of Humidity Stress: Recognizing signs of both low and high humidity stress allows you to take timely corrective actions.
DIY Solutions and Tools: Simple methods like misting, pebble trays, grouping plants, and using humidifiers can help maintain ideal humidity levels.
Seasonal Adjustments: Seasonal changes impact indoor humidity. Being proactive in adjusting humidity management techniques ensures that your plants remain healthy throughout the year.
The Science Behind Houseplant Humidity
Humidity plays a pivotal role in the health and growth of houseplants. Understanding the scientific principles behind humidity and its effects on plants can help indoor gardeners create an optimal environment for their green companions.
Why Houseplants Need Humidity
Transpiration Regulation: Plants continuously lose water through a process called transpiration, where water vapour is released from the stomata—tiny openings on the leaves. This process is essential for nutrient uptake and cooling the plant. In low humidity conditions, the rate of transpiration increases, which can lead to rapid water loss and dehydration. High humidity levels help regulate transpiration, ensuring that plants retain sufficient moisture.
Stomatal Function: Stomata play a critical role in gas exchange, allowing plants to absorb carbon dioxide for photosynthesis and release oxygen. Humidity levels influence the opening and closing of stomata. In high humidity environments, stomata remain open longer, facilitating efficient gas exchange and photosynthesis. Conversely, in low humidity, stomata may close to conserve water, which can limit photosynthetic activity and affect growth.
Hydration and Turgor Pressure: Adequate humidity ensures that plants maintain proper hydration and turgor pressure. Turgor pressure is the force exerted by water-filled vacuoles within plant cells, keeping them firm and upright. When humidity is low, plants lose water more quickly, leading to reduced turgor pressure and wilting. High humidity helps plants maintain hydration, supporting structural integrity and preventing wilting.
How Humidity Helps Houseplants
Photosynthesis Efficiency: Humidity directly impacts the efficiency of photosynthesis. In high humidity conditions, plants can keep their stomata open longer without losing excessive water. This allows for continuous uptake of carbon dioxide, which is crucial for photosynthesis. Enhanced photosynthesis leads to healthier, more vigorous growth.
Nutrient Transport: Water is the medium through which nutrients are transported from the soil to the plant. Proper humidity levels support consistent transpiration rates, facilitating the movement of water and dissolved nutrients through the plant's vascular system. This ensures that essential nutrients reach all parts of the plant, promoting balanced growth.
Stress Reduction: Plants exposed to low humidity conditions may experience stress, which can weaken their immune system and make them more susceptible to pests and diseases. Maintaining adequate humidity levels reduces stress and supports the plant's natural defence mechanisms, helping them resist infections and infestations.
Optimal Growth Environment: Many houseplants, especially those native to tropical regions, thrive in high humidity environments. Replicating these conditions indoors helps create an optimal growth environment that supports their natural growth patterns and physiological processes. Plants grown in suitable humidity levels exhibit better leaf development, vibrant colours, and more robust overall health.
Additional Insights on Houseplant Humidity
Humidity and Root Health: Proper humidity levels also influence root health. In high humidity environments, the risk of soil drying out is reduced, ensuring that roots remain adequately hydrated. This is particularly important for plants with fine root systems that are sensitive to fluctuations in moisture levels.
Symbiotic Relationships: Certain beneficial microorganisms, such as mycorrhizal fungi, thrive in humid conditions. These microorganisms form symbiotic relationships with plant roots, enhancing nutrient uptake and providing additional support against environmental stressors. Maintaining adequate humidity can promote the growth of these beneficial microbes, further supporting plant health.
The Houseplant Shop's Approach: Firstly, we like to group similar plants together to create microclimates of higher humidity in our plant growing areas. Secondly, we use trays or bowls of water placed strategically around the nursery to raise local humidity. As a last resort, we would use a humidifier, but with our current humidity management systems the staff do not have to adjust the humidity manually. Our humidity management ensures that the moisture in the air is always kept at levels to promote indoor plant growth, and maturity. We highly recommend using the same techniques that we do, as we find that our humidity can mostly manage itself. We actually find that at certain times of the year, due to how many plants we have, we actually have to run a dehumidifier! At our houseplant nursery, we believe that understanding the science behind houseplant humidity allows you to effectively monitor, maintain, and adjust moisture levels within your home. By maintaining the right humidity levels for each plant species, houseplants can thrive indoors, exhibiting healthy mature growth, vibrant foliage, and perhaps most importantly, resilience against stress, pests, and diseases.
Edited & Fact Checked By: The Houseplant Shop
Article Published: 27th December 2024
About The Houseplant Shop:
Independent Houseplant Nursery
Horticultural Specialists
Managing Over 250 Houseplant Species Onsite
Over 15 Years Of Experience With Horticulture
As head of horticulture, Sarah manages the care and propagation of over 250 plant species at a commercial houseplant nursery. With over 15 years of experience in horticulture, specializing in houseplants, Sarah has extensive expertise in plant biology, soil science, and integrated pest management. She continually reviews and integrates the latest research into her plant care guides. Dedicated to educating others, Sarah has spent years diagnosing houseplant care issues and sharing her real-world experience. Her commitment to scientific accuracy and helping people diagnose plant health issues has established her as a trusted authority and expert in the field.
The Houseplant Shop is a dedicated houseplant nursery, growing all of their own stock from their botanical library of over 250 houseplant species. The nursery staff are horticultural experts who have dedicated their lives to cultivating and nurturing over 250 different species of houseplants, focusing on Aroids, tropical plants, and NOID collectables. All their plants are grown in house in Britain to be more environmentally friendly. The nursery is proud to have been featured by the Royal Horticultural Society (RHS) as a 100% peat free nursery.
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How We Reviewed This Article:
Our horticultural experts continually monitor the houseplant space, and we update our articles when new information becomes available. We are committed to providing current and reliable information. If you have some information that you think would be helpful in this article, we'd love to hear from you. Our team works hard to revise articles for factual accuracy, and we regularly update our pages with new information, techniques, tips, images, trade secrets, and real world experience from the team here at the houseplant nursery. You can find a list of the article updates below.
Written By: Sarah Brooks, Head of Horticulture
Article Received: 18th December 2024
Copyright: The Houseplant Shop (https://thehouseplant.shop)
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Author: Sarah Brooks
Head of Horticulture at The Houseplant Shop