Laidback Gardener Tip of the Day

High Humidity Makes for Healthy Plants

décembre 10If the # 1 problem with houseplants during the winter months is giving them enough light, the # 2 problem is to making sure they get enough atmospheric moisture (humidity). The air in our homes becomes incredibly dry during the winter because heating systems remove moisture from the air. The colder it is, the more you heat… and drier the air.

How to tell if your plants are suffering from a lack of air humidity? First, dry air especially affects the plants with thin leaves. Plants with thick, leathery or waxy foliage are relatively resistant to dry air, as are plants with very hairy leaves. They do suffer, but not as obviously as others. Succulents – crassulas, sedum, cacti, etc. – are in this category, as are several peperomias and also the rubber plant (Ficus elastica).

Plants with thin foliage – brugmansia, abutilons, palms, ferns, etc. – suffer most from dry air. Often their leaves curl slightly down, their edges or tip dry out or blacken, they may hang limply even after you water or, most obvious of all, they simply fall off. Logically, houseplants should need less watering in winter, since  they are more or less dormant, but if you need to water as much as during summer or even more, that’s because they are losing a lot of water to transpiration and are not very happy.

A secondary symptom is poor blooming. When the air is dry, flowers dry up, wilt or abort or just don’t last as long as they should, even if the plant itself is relatively resistant to air dry. The thick, hairy leaves of the African violet, for example, are quite resistant to dry air, but the flowers suffer.

For these reasons, it is always wise to increase humidity in the rooms where you grow houseplants. The most obvious way is to run a humidifier in the room or to grow them over a humidity tray. Or simply grow a lot of plants: since each plant gives off moisture, the more plants you have, the greater the atmospheric humidity. Lowering the thermostat at night temporarily increases the ambient humidity and is also very effective. Or grow your plants in a naturally humid room, such as a laundry room (assuming that there is some sunlight!).

To maintain high humidity at all times for the most sensitive plants, place them in a terrarium… or in a clear plastic bag. They will remain in superb condition throughout the winter: humidity in a terrarium or a closed bag is as high as in a jungle and plants simply adore it!

décembre 10-2
A waste of time!

On the contrary, spraying plants manually with water, typically with a recycled Windex bottle, is a total waste of time, even if you see it frequently recommended. The effect only lasts a few minutes, plus it stains the leaves. Try anything else but this!

So there you go: a few tips on how to keep your plants happy during the heating season: put them into practice and you will soon have a real jungle of thriving foliage in your home!

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

1 comment on “Laidback Gardener Tip of the Day

  1. Pingback: Houseplants that Tolerate Dry Air – Laidback Gardener

Leave a Reply

Sign up for the Laidback Gardener blog and receive articles in your inbox every morning!

%d bloggers like this: