Humidity is an essential part of a plant’s life by providing moisture through the leaves for essential functions such as photosynthesis and cellular transpiration. Sometimes the humidity inside our homes is not enough for indoor plants to thrive. Indoor plants are typically tropicals which are used to environments where the humidity is often at 80% or higher. Without this humidity, leaves will dry out, photosynthesis can cease, and your plant will be in less than stellar condition and more susceptible to other ailments which can be tough to remedy.
There are multiple ways to add humidity to your home through methods such as humidifiers and misting but here we will be focusing on the pebble tray method, which is also known as a humidity tray.
Pebble trays are inexpensive, do not take up much space, and can be customizable which makes them an attractive option for those looking for quick ways to add humidity to their environment. Below we will explain how it works, if it’s an effective method, and how it compares to other methods.
Do Humidity Trays Really Work?
Humidity trays work to an extent. Humidity trays work for supplementally adding humidity to an area that is already at a normal humidity level and close to the tray.
If you are needing to go from minimal humidity to a high humidity there will need to be additional or entirely different methods implemented as the humidity tray method works in a very localized manner, often capping out at effectiveness at around 12 inches or 25 centimeters above the tray.
Additionally, pebble trays work to increase humidity at a negligible percentage than what the room’s ambient humidity is, so it’s often not enough on its own to do the trick. There is no harm in having one as long as the plant is not submerged in any water and is just sitting on top of the rocks or pebbles, but it should not be solely relied upon for drastic changes in the air’s moisture content.
The results may vary based on many different factors such as time of year and ambient temperature in the house, so experimenting on your own with what works and what doesn’t work is key to finding success with your indoor plants.
How Do Pebble Trays Work?
Pebble trays work by filling a shallow tray containing pebbles with water and setting your potted plant on top of the rocks—but not in the water. This allows for evaporation of water around the plant, without having the plant sit in water, and increases the moisture content in the air around the plant.
This is most effective for small, shorter plants as the humidity provided only rises a couple of inches from the surface of the pebbles. The water should be filled to about halfway up the pebbles or rocks used and refilled when it gets below for optimal usage.
The rocks or pebbles keep your plant above the water line, and the evaporating water gets into the pot through the drainage hole, raising the humidity in the pot itself as well as its immediate surroundings.
While raising the humidity is good, a negative consequence could be the additional humidity that gets trapped in the pot. Depending on how wet the soil is and how much sunlight the plant is getting this additional humidity could create an environment more conducive to fungal or bacterial growth in the soil.
How Effective are Humidity Trays?
Humidity trays are effective at increasing moisture in the air across a small area. If your plant needs a significant boost in humidity, say going from 40% to 60%, this method will not cut it.
For plants that prefer 80%+ humidity levels you will not get sufficient added moisture through a pebble tray alone. This is where a humidifier would come into play as a way to increase the humidity of a whole room instead of a small section. In a section below, we compare a pebble tray to a humidifier.
If you are trying to add an extra bump of humidity to your plant that is already thriving in its environment and maybe needs some supplemental moisture in the air, a pebble tray will be just fine. Other than that, they are not the most effective way to add much needed moisture to an environment that is already lacking.
Which Plants Like Pebble Trays?
Most indoor plants are tropical plants which have an affinity for humid environments.
The plants that would benefit from having a pebble tray the most would be:
- Spider plants
Generally, any tropical plant will appreciate an addition of a pebble tray or other moisture-adding element to their environment. This is a good way to boost humidity consistently over a period of time without having to mist throughout the day or invest in a humidifier.
Small, short, or trailing plants would be the best candidates as the humidity from the pebble tray is most effective closer to the source of the water. Just make sure the pot is not actually touching water and there is no concern about overwatering or root rot occurring with this method.
Plants you will want to avoid keeping in an area of too high humidity are plants that have evolved to survive in arid conditions such as cacti, snake plants, and aloes. A bit of ambient humidity won’t kill them but these plants have adaptations which make them less likely to lose water throughout the day, like succulent leaves or a thick cuticle which prevents water loss through their pores, also known as stomata. It pays off doing research on the plants you bring home because what is good for one type of plant is not always good for all types of plants.
Pebble Tray vs. Misting
A pebble tray is an easy way to provide your plant with a consistent, albeit minimal, boost of humidity. They can be homemade for minimal to no cost, and there is no risk of getting water on your plant’s leaves like there is with misting.
Misting your plants provides a short-lived boost in humidity that is likely not to make an impact in your plant’s life unless your plant does not need too much additional humidity. However there is the risk of water settling on the leaves which can bring some issues for more sensitive plants such as the Fiddle leaf fig. Water can carry bacteria that can weaken your plant’s immune system if too much gets sprayed on the leaves. This can cause disease in the plant which can potentially spread to other plants in the same area, so it is best to avoid getting the leaves too wet.
Overall, a pebble tray would provide a similar amount of humidity over a longer period of time as misting would, without the risk of spraying contaminated water on your leaves. For how inexpensive and easy it is to set up, it could possibly be better to set up a pebble tray rather than worry about misting frequently enough and with enough volume to make a difference in the humidity levels of the area.
Humidity Tray vs Humidifiers
Humidifiers are a much more effective way to raise the humidity of a whole room rather than a small area around a plant. They are perfect for plant rooms in houses or any room where it is dry and you have tropical plants. They can be relatively small and inexpensive, so if you are having chronic plant problems revolving around humidity it would be worth the investment in order for your plants to thrive. Dry, crispy leaves or curling of the leaves are some immediate signs that your plant needs more water in the air to help regulate their own temperature, as well as perform cellular functions necessary for growth and survival.
Humidity trays serve their purpose more on an individual scale rather than increasing the air’s moisture in a large space. If you have a couple of small plants scattered around, pebble trays may be a more effective and efficient way for you to provide some extra humidity so long as you are able to stay on top of refilling the tray as needed. If you have a whole plant room full of tropicals you will definitely want to have a humidifier handy, if not multiple depending on how large of a space needs to be given supplemental moisture. If you want a humidifier for your indoor plants, I would recommend Levoit Humidifiers. They come in different price points to suit your budget.
Ultimately, pebble trays have their uses just as humidifiers and misters do, and it is dependent on many factors regarding what method works best for each indoor plant enthusiast. Type of plant, humidity requirements, number of plants, and the size of your space all play into what source of humidity would be best for your given situation. It also depends on how humid your space already is, and how much more humidity you are looking to add to the air.
Humidity is an element of plant care that needs to be taken into consideration just as much as soil type, light requirements, and watering preferences are when purchasing a plant and taking it home.
With any of these elements not meeting expectations your plant will show signs of distress and be more susceptible to give into other stressors such as disease which are much more tedious and difficult to treat. These conditions can change depending on the time of year so it is always best practice to develop a relationship with your plants to know when something is lacking, what it is, and what can be done about it.
For an in depth analysis of how much humidity a pebble tray adds to a space, check out this experiment video to see if a pebble tray is the method for you.