Tips for Keeping Your Houseplants Healthy All Winter Long

Keep Temperatures Stable Around Your Plants

That prime spot near your window, where plants get the best possible light? It may actually be a bad spot, especially for sensitive plants. Unless your windows are well sealed, they’re prone to drafts and cold air. That goes double for any plant near an exterior door. The frequent temperature changes from opening and closing the door anytime you go outside or come back in can do a number on your greenery.

How To Keep Plants Warm in Winter

This isn’t the time of year to upgrade your windows, so check them for drafts with a lit candle or the smoke from a stick of incense. Position your plants so there are barriers between them and any sources of drafts. We recommend using weather-sealing tape or placing plants in a glass cabinet or tabletop greenhouse.

To complicate matters, baseboard and furnace vents are usually below windows as well. Rapid increases in heat are also a threat to your plants, so try to avoid putting them where they’ll get blasted by heat sources. Tropical plants are generally the most sensitive, so give them the safest locations and reserve the trouble spots for hardier greenery.

Provide Extra Humidity

Warm air “holds” more moisture than cool air because its faster-moving molecules create space for water vapor to fit in. In winter, the cold outside air becomes dry, and heating that dry air inside your house actually decreases its relative humidity (because you’re increasing its capacity to hold moisture, but not adding any).

How To Raise Humidity for Your Winter Houseplants

Misting your plants just isn’t going to do the trick, and wetting the leaves can cause problems with mold and pests. So, what’s a better solution?

You can start by putting moisture-loving plants — again, tropicals often benefit from this — in high-humidity areas of your home, such as the bathroom or the area just outside it. Another option is to cluster sensitive plants around a humidifier. However, the simplest and most versatile option is a much more low-tech approach. Place some decorative pebbles in a shallow dish that can accommodate your plant’s pot, pour in enough water to almost cover the pebbles, and then stand your pot in the center.

As the water evaporates, it creates a small pocket of higher humidity around your plant, and the pebbles keep the plant’s roots out of the water. Top it up as needed to maintain the water level. 

Cut Back on Watering

This may sound counterintuitive, after what I just said about humidity, but it’s true. The simple fact is that plants aren’t as biologically active during the short winter days and long winter nights. That period of dormancy or semidormancy is hard-wired in their DNA, the same way hibernation is for a bear.

The goal is to conserve the plant’s energy for spring when the growing season arrives again. Your plant may even shed some leaves because it doesn’t need them to photosynthesize the reduced winter daylight and there’s a metabolic cost to carrying those extras.

How Often To Water Indoor Plants in Winter

If you scrolled to this point in search of a number, I’ll have to disappoint you. Watering frequency depends on several factors, including the size and type of plant and the potting soil you’ve used. The only meaningful answer is “when the plant needs it.” To find out if the plant does in fact need it, poke a finger into the soil. If the top inch or so has dried out completely, it’s time to water. If you don’t want to get your fingers dirty or have a small pot that’s difficult to check without damaging the roots, you can use a moisture meter to tell you when the soil is dry.

Underwatering is better than overwatering, which is a common reason houseplants die. Soggy soil can lead to root rot and pests, so be prudent. If you water a plant every week in summer, for example, start checking it around the 10-day mark and feel your way from there.

Be Mindful of the Light They’re Getting

Days are short and nights are long in wintertime. That means you may need to rethink your houseplants’ locations, so they can get the light they need. A lot of houseplants tolerate surprisingly low levels of light (pothos, for example), especially during the winter/dormant part of their growing cycle. But other plants will need your help to remain healthy and attractive during the colder months. That’s especially true of any plants you want to bloom in winter, because you’re encouraging them to expend extra energy at a time when it’s hard to come by.

Winter Light for Plants

Not all windows receive adequate sunlight, so place the most light-hungry plants near the ones that do. Plants that are happy with less light can be divided among the remaining windows. If you’re not able to arrange enough natural light for every plant, you’ll need to fall back on supplemental lighting. It can be low-tech, though: Placing a mirror on the wall where it can reflect light back toward your plants helps a lot, although you should avoid using a magnifying mirror or multiple mirrors directed at the same spot, as this could potentially start a fire. You could also make a DIY “sun box” with aluminum foil and cardboard. Otherwise, you’ll need grow lights.

The best grow lights for houseplants are usually LED-based. They’re available in all shapes and sizes, consume little electricity, and are readily available at major retailers. At my house, we use ring-shaped grow lights with telescoping arms that push right into the soil and can be extended to raise the light above the plant. Aside from helping the plants grow, they make the whole room brighter and more cheerful. That can be a real mood-booster on those dreary winter evenings.

One final tip: Take note of where you placed each plant and how well it flourished, so you can draw on this year’s experience when next winter rolls around.

Keep Your Plants Clean

If you have forced-air heat or a heat pump, you may find that your plants get dusty more quickly in the winter. Dust on the plants’ leaves reduces the amount of light available for photosynthesis. If you let it build up, you’re effectively putting your houseplants on a diet. There’s a time for everything, and winter — when light is already scarce — is just not the time.

An additional benefit to regular cleanings is that you’ll get a close-up look at how your plants are doing. It’s a good time to carry out other routine “housekeeping” tasks like removing dead leaves, deadheading winter blossoms as needed, and checking for pests or diseases.

How To Clean Your Houseplants

Using a Swiffer or a similar electrostatic duster is a quick way to remove dust from plants with flat leaves, but it’s more of a temporary solution than a deep cleaning. Wiping down broad-leafed plants with a damp microfiber cloth is an effective option — I do this with our tree-sized dracaena. For plants with smaller leaves, you may need to use a cotton swab or twist your cloth to a point and use that.

This type of cleaning is a chore, but if you can block out time for it every couple of weeks, it will help a lot. The “ounce of prevention” option is using an air purifier in the room to suck excess dust out of the air before it lands on your plants. Just remember to position it so the filtered air isn’t blowing directly on your plants (because that’s a draft, and they don’t like drafts).

Don’t Let Pests Get a Foothold

It’s an unfortunate reality that winter presents an opportunity for pests and diseases to have a run at your houseplants. Spider mites are a major threat, since they can infest a wide range of houseplants; will be well established by the time you spot them; and like dry conditions, so dry winter air and reduced watering suit them just fine. 

If you bring plants in from the outside for the winter, there’s a high likelihood that you’re bringing pests along with them.

Winter Houseplant Pest Control

Keeping your soil wet deters spider mites but promotes root rot and fungus gnats, so that’s a no-go. Mites can be washed away with a spray bottle or wiped off with a damp cloth, and removing the top inch or so of soil can help as well. As for other common pests such as aphids, whiteflies, and mealybugs, physical removal and washing helps with those as well.