Humidity and Houseplants

-Mike Weeks- It’s still summertime in the South, but soon enough we’ll be getting our fireplaces, stoves, and furnaces running. And while that may keep us toasty warm, all of that dry heat can cause our tropical houseplants to suffer. Most common house plants are tropical plants, so they are used to moderate (at least) humidity in their environment. This blog post will provide some easy methods to help you help your plants survive the arid air of winter..

First off, when considering a location for your plants, be sure to keep them clear of heating vents or drafty areas. Consider the plants’ lighting needs as well. As long as there’s a good window, there’s a group of plants that will grow in that space, but make sure the window has a tight seal so cold drafts won’t harm tender tropical foliage.

If you keep a hygrometer around, you’ve probably seen how low the humidity can drop once fall rolls around and temps begin to drop. I’ve seen my relative humidity drop to around 30%, and that makes for very sad plants. Plants are forced to transpire more moisture through their leaves whenever the air is dry, but If there’s enough humidity in the air, the plant gets to retain that moisture. Now, how do we achieve higher humidity without turning our entire house into a jungle? Here are a few tips for creating small microclimates for your plants to thrive indoors over the winter.

Grouping – Artistically arrange your plants into groups, allowing them to huddle together. This allows transpiration from one plant to provide humidity for another plant, and so on, creating a tropical microclimate. The soil from each container also adds to moisture to the air, as water in the soil evaporates. While this increases the ambient humidity, it also means more frequent watering than summer months.

Humidity Trays – They are easy, and you can make them with any kind of tray that will hold water. Essentially, your plants sit in a tray or saucer that is filled with rocks, clay pebbles, or marbles, and water stays in the tray, filled just below the medium level. As the water evaporates from the tray, it creates a field of humidity around your plants. I’ve used the heavy duty propagation trays and saucers, but you can get creative. As long as the tray holds water and doesn’t rust, it can be used. These trays are especially useful around plants that don’t like to be misted, such as African Violets. Generally, we stay away from misting fuzzy leaves.

Misting – Some plants just like a good misting – up to a few times a day, if possible. Plant misters come in lots of sizes and styles, from pretty glass misters to utilitarian spray bottles; just make sure your mister produces a nice fine mist, rather than a stream or heavy spray. As far as misting itself, I spray my plant’s leaves, but I also spray the pot and the area around it. This will allow more moisture to evaporate into the microclimate. Consider occasionally using a diluted seaweed solution when you mist, as this can provide essential nutrients directly to the plant’s leaves. Avoid misting your plants at night.

Indoor Greenhouses – Sometimes this can be the best option if you have really dry air. Indoor greenhouses are affordable and easy to set up. They can be near a bright window or placed anywhere with the utilization of a grow light. By collecting plants together in a semi-closed space, moisture is retained in their environment.

Humidifiers – This is probably an obvious solution, but one that we should not overlook. Along with our plants, we can appreciate the extra moisture. A good humidifier is your best choice if you have a big plant collection.

***A word on air conditioners. This post focused mainly on how to create an atmosphere for plants during the fall and winter, but it is worth noting that running an air conditioner will also lower humidity significantly. If you prefer the temps on the cooler side, consider shaping your plant collection around that. There are groups of plants that will tolerate your lower temps such as African Violets, ZZ Plant, Sansevieria, and succulents, to name a few.