A No-Fuss Guide To Plant Humidity & How To Know What Yours Need
Many of the plants that live happily in our homes hail from the rainforest, where things are decidedly humid. Greenhouses, in which most indoor plants will spend time before they make their way to retail stores and then to us, provide the ideal growing environment for indoor plants, where diffused light from above abounds and humidity is high.
Our homes, on the other hand, are generally fairly dry environments, and this change can be quite a shock to the system for new plants. If humidity is really low (often due to air conditioning or heating), a plant's roots will struggle to absorb an adequate amount of water to keep up with the moisture lost through the leaves.
Take a look at the leaves.
As a general rule, the thinner the leaf, the greater its need for humidity. Thick, leathery, or waxy leaves, or those covered with hair, are usually relatively immune to dry air.
While succulents and cactuses can deal with much drier conditions, both above and below the surface, tropical plants enjoy a relative humidity of around 50%.
There are a few things you can do to manage low humidity. One solution is to regularly spritz your plants' leaves with a water mister. This is best done in the morning and with tepid water so the foliage has a chance to dry out during the day (good ventilation will assist here, too).
Sitting your humidity-loving plants on a saucer filled with pebbles and water is another useful trick. This creates a moister environment around the plant while ensuring that it isn't sitting in a pool of water potentially causing root rot. Grouping plants together can also increase the moisture levels around foliage by creating a microclimate that helps boost humidity.
If you're really serious about providing your indoor plants with the steamy jungle conditions they so desire, then a humidifier is the way to go.
The 3 levels of humidity needs:
Plants that don't require humidity.
Encompassing cactuses and most succulents, these plants prefer dry conditions and will not tolerate misting, which can lead to fungal issues and other problems. Mist plants weekly in summer, if you like, but ultimately they will be fine without.
Plants that like medium humidity.
Many common indoor plants benefit from a spritz once a day or so. Try to group plants with similar humidity requirements together, and consider sitting them on a pebble tray filled with water.
Plants that thrive in high humidity.
We refer to these as "humidifier plants"—high-maintenance varieties, such as many anthuriums and those sensitive tuberous begonias, which require high levels of ambient humidity but won't tolerate water on their leaves. Such levels can't be achieved in our homes without the help of a humidifier.
Reprinted from Plantopedia: The Definitive Guide to Houseplants by Lauren Camilleri and Sophia Kaplan, with permission by Smith Street Books, 2020.