December 21, 2016
7 Tips for Winter Houseplant Care
You know how sometimes you wake up on a dark, winter morning and your nose feels so dry it hurts to breathe? If the air in your home or apartment is so dry you wake up craving a drink of water, it’s safe to say your plants feel the same. So how can you keep your houseplants happy?
1. FIRST, RAISE THE HUMIDITY
Many of our favorite house plants are native to the tropics, where relative humidity may be up to 90%. In contrast, the humidity in the average home, in winter, is about 20%. As a result, thin leaved plants may develop brown edges or their leaves may curl and split. Grouping your plants together in a single area helps raise the humidity a little, but to make a more substantial difference, try growing your plants on a dry well.
2. MAKE A DRY WELL
Take a large saucer (18” in diameter) or a window box tray and fill it with small aquarium pebbles almost to the top. Arrange several potted plants on the tray or saucer, and pour water onto the pebbles, until the water comes just to the top of the stones. The plants should not be sitting in water (this can cause root rot), but the water should come up just to the bottom of the pots. As the water evaporates over the next few days, it raises the humidity around the plants. Check the water level daily and top off as needed.
3. SAY ‘NO’ TO THE PRETTY HOUSE PLANT SPRAYERS
And before you ask, No! Don’t mist your plants with a spray bottle! Misting a plant is a very short term solution. You would pretty much have to quit your job to stay home and mist your plants all day long, because as soon as the water dries on the leaves (which only takes about 5-10 minutes in winter), the effectiveness of that misting is over. Building a drywell is an easier, much more efficient way to raise the humidity for your plants.
Plants with thick, succulent leaves and stems are more tolerant of dry air. If you’re thinking of buying a few new plants for indoor winter greenery, consider mistletoe cactus (Rhipsalis), wax plant (Hoya species), and moth orchids (Phalaenopsis). These low maintenance, lovely plants are tough enough to thrive indoors without supplemental humidity.
4. LET IT BE LIGHT
What about light? Not only is the angle of the sun lower in winter, so sunlight is less intense, but we also get less of it, since the days are shorter. You can deal with this in two ways.
The easy way: let your plants slide into semi-dormancy. Many plants naturally grow more slowly in response to cooler temperatures and shorter daylight hours. They’re still alive, but they don’t flower as much, and they don’t produce as many new leaves. (There are some exceptions to this, like holiday cactus and orchids that bloom in winter, but we’ll get to those in a minute.) Most of us grow our plants on window sills, because that’s where the light is. Temperatures near windows are usually 5 to 10 degrees cooler than at the center of the room. So without doing anything, you can let your plants grow more slowly and adjust to these seasonal conditions.
5. NOT JUST ANY LIGHT BULB
If you want to keep your plants in full, active growth, or if you have some plants that grow most actively in winter (like the aforementioned holiday cactus and many orchids), consider adding a grow light to your indoor garden. The most efficient grow lights are fluorescents and LEDs, and because they lose so little energy as heat, they can be as close as 6 to 8 inches from your plants. But, remember, you can’t just use any light bulb. Plants use specific parts of the light spectrum for growth, and most of our household light bulbs don’t provide this. Because the light from bulbs is less intense than light from the sun, you’ll need to make up for the reduced quality by increasing the quantity. Keep your grow lights on for 15 – 18 hours per day.
6. HOLDING ON TO YOUR SUMMER ANNUALS IS HARDER THAN YOU THINK
Some gardeners can’t bear to part with their favorite summer annuals, so they bring them indoors to overwinter. I’m not saying this is impossible, but don’t expect these plants to grow the same way they did in the outdoor, summer garden. Because your indoor growing conditions are darker and less humid, outdoor plants may become leggy, producing smaller leaves, spaced more widely apart, with less vibrant coloring. Shade annuals, like coleus and begonias, will do better than annuals that require full sun, but with most outdoor plants you’ll need to adjust your expectations. Focus on helping them survive the winter indoors, then in spring, cut back the weak, indoor growth and move them outdoors, where they really want to be.
7. AVOID UNINTENTIONAL DOMESTICATION OF BUGS
One more thing to look out for in winter is insect pests and spider mites. (Technically spider mites are arachnids, not insects…they have eight legs) Warm, dry growing conditions allow pests to multiply at a rapid rate, and indoors there are no natural predators to keep the pest populations in check. Be sure to take a good look at each plant when you water. If you spot a problem early on, you’ll be able to control it and keep your plants healthy. Once pests get established indoors, they can spread rapidly and may be hard to get rid off. And most apartments are just not large enough to host an abundant variety of critters under the same roof.The tropics are warm and sunny, lush and humid. The gentle, soft air feels wonderful on your skin. If you can’t pack up your houseplants and take a long tropical vacation, at least you can give them a little TLC at home to get them through the dark, dry days heading our way.