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Watering Houseplants in Winter: Not So Simple

Sometimes you have to water houseplants more in winter, not less. Source: http://www.clker.com, pluspng.com & hugohd.com, montage: laidbackgardener.com

I always find questions about watering indoor plants complicated.

Everyone seems to want me to simplify things and recommend “water once a week” or “water every two weeks,”, but it just doesn’t work that way. Plants need water when they need water, period. The same plant might need watering after 10 or so days during a long period of gray weather, weekly watering when the sun shines on and on … and possibly even watering every two or three days if it’s become huge, yet is still growing in a tiny pot.

You just can’t decide on a specific watering frequency and stick to it no matter what. Do that, and you lose plants!

Also, seasonal differences have an effect … but not necessarily the effect you’d think.

Water Less in Winter?

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When temperatures drop, watering needs can actually go up! Source: http://www.vanbeeks.com

Take watering in winter. Logically, you’d think plants would need less frequent waterings in winter, because they grow less (in fact, many don’t grow at all). And that will be true in many cases, but not all. Because the other current effect of winter conditions indoors is dry air and plants lose more water to evaporation when the air is dry (and therefore need to replenish it from the soil).

I try to keep the relative humidity at about 50% all year, perfect for humans, although barely acceptable for many plants (most would prefer 70% or even more) … but often fail. As I write this on a cold morning (-4° F/-20° C), the relative humidity is a decent 47% upstairs, where I have more plants (and more plants produce more humidity), but an abysmal 28% in my basement office where there are fewer of them. Cold temperatures outdoors often mean drier air indoors, as air loses its humidity when you heat it (that is, in fact, why it’s called “relative humidity”: it’s relative to the quantity of water the air can hold at any given time).

This will show when I water my plants: many of my upstairs plants won’t need watering at all, as they’re not putting on much growth and the humidity is decent, yet the soil in many of my basement plants will be very dry, even though I last watered 4 days ago.

Succulents Versus “Other Houseplants”

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Most desert cacti love a dry winter just above freezing. Source: http://www.teepublic.com, http://www.clker.com& clipart-library.com

Desert cacti and other succulents are of “least concern” in winter. They don’t mind their soil drying out, doubly so when light is low and temperatures are cool. If I could keep the air temperature down to about 40° F (5° C), which I can’t do (I’d have to write wearing long underwear, snow plants, a parka, a tuque and gloves!), I wouldn’t need to water some of them all winter. Instead, I water them when their potting mix feels “really dry” to the touch and that can indeed be infrequently, perhaps every 2 to 3 weeks.

My other houseplants don’t like their soil to ever dry out completely and will need to be watered much more frequently. I always check twice a week and water only those plants whose soil is dry to the touch*. And when I water, I water. I always give the rootball of any plant a thorough soaking.

*There is a small group of exceptions: semi-aquatic plants and plants of their ilk, like the umbrella plant (Cyperus alternifolius). I keep those soaking in water at all times.

So, just be aware that it is often necessary to water plants more during the winter than during the summer. It all depends on your growing conditions.

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 “Watering Houseplants in Winter: Not So Simple

  1. I find watering needs very different in winter….it’s always the touch test…. mainly i tend to overwater the things in plastic pots and underwater clay pots…

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