Ill.: Claire Tourigny, from the book Les 1500 Trucs du jardinier paresseux

Most houseplants adapt fairly well to indoor conditions, otherwise we wouldn’t be growing them as houseplants, would we? But a few have a hard time with winter conditions indoors. Low light is one problem (winter days are short and often cloudy), but you can help by moving the plants nearer to a window or placing them under plant lights.

For many plants, though, the real problem is dry air.

In many homes, keeping the relative humidity much about 30% can be a struggle in the winter, especially in climates where heating is necessary. Yet most plants prefer 50% humidity and greater. The more you heat, the lower the ambient humidity, so the colder your climate, the worse the problem will be.

Again, you can help by running a humidifier, by placing the plants on a humidity tray or by grouping plants together (that creates a very localized bit of jungle atmosphere). You can usually manage to get closer to 50% humidity that way and most plants will appreciate your efforts. But that’s not enough for all plants.

You can also waste your time by misting your plants (certainly one of the most useless gardening tricks ever invented: it doesn’t help plants in any way).

Humidity-Lovers

Some—even most—plants like really humid air. 70% or above. That’s too much for people, can create condensation problems and is, at any rate, very hard to maintain indoors in any open area. But you can do so “under glass”: a closed environment where humidity can rise to 90% or more.

One easy solution would be to move humidity sensitive plants to a terrarium for the winter. If you cover or partially cover a terrarium, you can easily maintain high humidity. However, many houseplants are too big for a terrarium. But what you can do is to seal them inside a clear plastic bag for the winter.

True enough, this isn’t going to look very elegant, but if you really like the plant and the way it looks in spring and summer, is a few months inside a plastic bag that much of an annoyance?

So Simple to Do

Here’s what to do, step by step.

1. Find a clear plastic bag of an appropriate size (bags from the cleaners are ideal for larger plants).
2. Prepare the plant by cutting off any dead or dying foliage, as dead leaves will tend to rot under high humidity. This is not harmful to the plant, but is aesthetically doubtful.
3. Water the plant normally, then wait a day or two or three: you’ll want the soil to be slightly moist, but not wet.
4. Place it in the bag.
   

   You can use stakes to hold the bag above the leaves if you want, although that isn’t absolutely necessary. Photo: bhg.com

5. Seal the bag shut with a twist tie.
6. Place the plant in a bright location, but away from direct sunlight, otherwise the temperature in the bag could become unbearably hot.
7. Don’t worry if there is a bit of condensation at night, but if there is a lot during the day, open the bag for a few hours to let the excess humidity out, then reseal.

Plants sealed inside clear plastic bags will probably not need watering nor indeed any care whatsoever, even after several months. This is truly an ideal technique for laidback gardeners!

No, The Plant Won’t Suffocate

Don’t worry that your plant will suffocate inside a sealed plastic bag: remember that plants recycle the air they breathe, absorbing carbon dioxide and producing oxygen during the day and absorbing oxygen and producing carbon dioxide at night.

The humidity in the bag will reach a very high level, often close to 100%! Leave the plant in its own personal greenhouse as long as you’re heating your house daily. Then remove the bag when humidity levels soar again in spring and summer.

Which Plants to Bag

Actually, most houseplants other than succulents* would adore spending their winter inside a plastic bag, but they look better uncovered and part of growing houseplants is the pleasure of integrating them into your home décor. So nix that!

*Succulents, including most cactus, actually prefer fairly dry air and won’t need special coddling when it comes to relative humidity.

However, any plant whose leaves tend to dry up excessively during the winter isn’t giving you much of a show and would be a good candidate for bagging.

Among the plants that often struggle with dry winter air are the following:

• Alocasia (Alocasia spp.)
• Baby’s tears (Soleirolia soleirolii)
• Coral bead plant (Nertera granadensis)
• Creeping fig (Ficus pumila)
• Episcia (Episcia cvs)
• Ferns (many species)
• Homalomena (Homalomena spp.)
• Little tree plant (Biophytum sensitivum)
• Medinilla (Medinilla magnifica)
• Miniature sinningia (Sinningia pusilla and others)
• Nerve plant (Fittonia argyroneura)
• Orchids (some species)
• Peacock plant (Calathea spp.)
• Prayer plant (Maranta leuconeura)
• Rex begonia (Begonia rex)
• Rex begonia vine (Cissus discolor)
• Spikemoss (Selaginella spp.)
• Tropical pitcher plant (Nepenthes spp.)
• Umbrella palm (Cyperus alternifolius)

A plant in a bag: a simple solution of a common houseplant problem!