The plants that live indoors with you need special care to get through the coldest, darkest months of the year. To share her expert tips on winter houseplant care, joining me on the podcast this week is Maria Failla of Growing Joy.
Maria is the host of the Growing Joy with Plants podcast and the author of “Growing Joy: The Plant Lover’s Guide to Cultivating Happiness (and Plants).” She formerly lived in a tiny apartment in New York City but now lives in a house in upstate New York, which offers more room for raising plants but is also a challenging environment due to how dry and cold it gets, not to mention the shorter day lengths in winter.
Wintertime is often gloomy, cold, snowy, rainy and dark. It’s all the things we don’t want it to be, because as gardeners, we want to see the light and be outside and be warm and get our hands in the soil — and that’s not happening during the wintertime. But one of the things that makes us feel a lot better is having our houseplants inside. But when they’re not looking good or performing as well as they could, that can bring us down.
Maria shares her advice and ideas to help houseplants look their best in winter. We’ll discuss what is causing those plants to go quiet on us and what we can do to perk them back up. God knows we want something to do related to plants at this time of year.
Houseplants gave us something new and fun to do related to plants in those months of the year when otherwise there is not much to do besides make plans and look at seed catalogs.
“I will preach the emotional benefits of houseplants until I take my last breath,” Maria says.
There are so many similarities between humans and plants, she says. To that point, she notes that she has never met a houseplant that likes the winter. “It’s not going to be the time for your houseplants to be thriving and putting off a lot of new growth,” she says.
Having gone through seven winters now with her houseplants, Maria says she has learned a lot through trial and error, including frying some houseplants on her radiator and through overwatering and underwatering. She wants to help others avoid her missteps.
Before continuing, I want to pause a moment to let you know my Online Gardening Academy™ Master Seed Starting Course will open up for enrollment on January 23. Sign up to be notified. You can also register right now for my free webinar Seed Basics & Beyond: 9 Things to Know Before You Start Plants From Seed. There will be four opportunities to attend between January 24 and 27.
What Houseplants Need in Winter
Maria advises gaining a better understanding of where a houseplant is from and what its normal growing environment is to manage it the best that you can and give it what it’s used to.
When considering what houseplants need from us in the winter, it helps to zoom out and think about where the plants would thrive in nature. The majority of houseplants are tropical plants. For example, Monstera is a coveted houseplant in the United States, though when Maria visited a rainforest in Costa Rica, she saw wild Monstera climbing trees.
“A lot of the houseplants that we know and love, that we care for indoors, actually are understory jungle plants,” she says. They get frequent rain and they live in 80-90% humidity and dappled sunlight.
When brought inside, it’s a rough transition. Maria notes that her home in upstate New York is dry and experiences four seasons and snow — unlike the rainforest.
“That’s okay because they’re hardy and we’ve learned how to cultivate them and keep them indoors, but winter is when they’re up against the most for their level of discomfort because there are so many things that are different from their natural environment,” she says.
Light levels are drastically lower in winter, she points out. “The amount of hours that our plants are actually getting light are shorter. And also the position of the sun in the sky is lower in the winter so there’s less light availability.”
Houseplants make their own food through photosynthesis, Maria notes. “If there’s less light, there’s going to be less food that they can make for themselves. I think that’s the biggest change and the biggest thing that plants suffer.”
Maintaining Houseplants in a Heated Home
Whether your home has forced air heating, a fireplace, baseboard heaters or radiators, there is hot, dry air circulating in your home in winter. Though your home naturally gets hot in summer, there is more moisture in the air in summer. The dry hot air of a heated home in winter is what’s a problem for houseplants.
There is also more volatility in temperature in winter. Some nights will be colder than others, and there may be drafty windows.
“These things are normal for us. We might not recognize that these things are going to make our plants uncomfortable,” Maria says. “Your plants can totally thrive in these circumstances. Your plants can totally be happy and bloom for you and grow new leaves, but you need to kind of understand what’s going on in order to intervene before it’s too late.”
Outdoors, plants drop their leaves and go dormant in winter. “You’re not going to experience such extreme dormancy with a lot of our houseplants because they’re indoors,” Maria says. “They’re not experiencing the true winter. They’re experiencing the internal, 70 degrees version of winter because of your heating system.”
Though houseplants are not completely dormant in winter, they are experiencing quiescence — a period of quieting. Houseplants may start yellowing, drop some leaves and cease growing in winter, and that doesn’t mean you’re doing anything wrong, Maria says. The plants are recognizing the rhythms of nature and noticing that there is a shorter photoperiod.
Maria’s Tips for Winter Houseplant Care
Maria runs down her top tips for taking care of houseplants in winter and reminds us to take our personal home environments into account rather than assuming all advice is one-size-fits-all. A number of factors could mean that what applies to Maria in the North or me in the South does not apply to your situation.
Be Mindful of Your Windows
Because there’s less light availability in winter, you want houseplants to get every morsel of light they could possibly get. Clean your windows before the winter. If those windows are giving your plants their source of food — light — make sure those windows are clean so the plants get as much light exposure as they can, Maria advises.
Old windows can also be sources of drafts. A houseplant will not take well to a drafty window sill in winter. If you touch a pot that stays near a window and the pot feels cold, there is likely a draft.
Houseplants would prefer an environment that is 80°F and humid. “That’s what these poor little plants want, and they’re compromising to hang out with us in our 70-degree, 30% humidity home,” Maria says.
Tend to the Leaves
While settling in for winter, if you notice leaves have begun to yellow, it is okay to do some preemptive pruning. As a plant prepares for a period of less light, taking off those leaves that aren’t doing well anyway will allow the plant to conserve resources rather than push nutrients and moisture to a dying leaf. A cleaned-up plant is also easier to inspect for signs of decline.
It’s also a good time to clean the remaining leaves. Leaves that become covered in dust cannot photosynthesize as well as a clean leaf. Leaves can be cleaned with a wet paper towel, though Maria recently discovered houseplant duster gloves and enjoys cleaning with them. You can also put your plants in the shower and rinse them down — though this is best done before the temperature plunges outdoors.
Use a Hygrometer
Humidity can plunge in winter to shockingly low levels. Maria monitors her indoor humidity with a hygrometer and found that the humidity level dips to as low as 14%. “That is not good humidity for human lungs, let alone plants,” she says.
A low humidity issue presents itself as browning on the leaf margins around the whole plant.
Maria does not recommend spritzing plants with water. “You give a couple of spritzes and maybe it adjusts the humidity for like 30 or 40 seconds,” Maria says. “And then it’s going to go right back down. If you spritz plant leaves and water sits on the leaves, that can increase fungal infections.”
She also doesn’t subscribe to using a pebble tray. This is a tray full of pebbles, with water added, that the pot sits on top of. She tried this and did not observe a difference using her hygrometer.
What she has noticed is that grouping plants together does increase humidity by a couple of percentage points because plants transpire moisture. She recommends grouping plants in a small room and using a humidifier. “Your lungs and your skin will thank you for it as well,” she adds.
For an individual plant, a glass cloche over the pot can maintain humidity levels.
Beware Houseplant Pests
“Winter is when a lot of houseplant pests are going to descend,” Maria says. Because pests seem to descend when plants are susceptible — like when plants are a little bit sadder, when they are suffering from seasonal affective disorder — that’s when you’re going to see thrips.”
On a daily or weekly basis, more often than you water the plants, check the underside of leaves and where the leaves attach to the stem for signs of pests. For example, webbing is a sign of spider mites.
Occasional showers are great for pest control because they knock the pests off of the plant, Maria says.
Houseplants that live outside for the summer may harbor pests. Those pests could hitch a ride indoors when plants are brought in for the winter and then create havoc on all of your indoor plants. Likewise, a new plant brought home from a garden center could also introduce pests. This is why it is important to inspect plants before moving them indoors. Maria inspects plants using a jeweler’s loupe.
Pests could also come from larvae present in the soil or they could come in through a window. Maria says once pests are spotted, start treatment immediately. In fact, she keeps pesticides on hand so when a pest issue does arise, there will be no delay in treatment.
Plants generally require less water in winter because they are photosynthesizing less and water is not evaporating from the soil as fast. But Maria acknowledges every house is different.
“If you water your plants every Monday and Monday rolls around and you notice that your soil is still moist, you might not need to water it,” she says.
Maria waters more in winter due to how dry her house gets and also because her houseplants are in terracotta pots up on plant stands above baseboard heat. The terracotta pots pull moisture out of the soil, unlike plastic pots, so she needs to be that much more conscious of watering.
Maria encourages everyone who takes her advice to put it through their own lens. For example, someone living in a humid area like the Pacific Northwest won’t need to water nearly as much as she does. Take those differing circumstances into account.
Put Plants Under Grow Lights
“Sometimes nothing’s going to fix your plants, nothing’s going to keep your plants happier than just putting them under some grow lights,” Maria says.
You can use the grow lights that you have on hand for seed starting.
“I have taken my jumpstart seed starting T5 lights and resuscitated houseplants so many times,” Maria says.
High-light plants such as Crotuns, succulents, cactus and ficus won’t be happy without light. Giving them a grow light, even if it’s just for the winter, will make them happier. You can even buy grow light bulbs and add them to your existing lamps rather than purchasing a whole new setup.
Grow lights can burn plants. Foliage that turns pink or brown is likely too close to the light source. LED lights are deceivingly powerful, and that intensity can fry foliage. Provide a gap between the tops of the plants and the lights. The grow light you buy may include directions that tell you just how many inches to leave between the lights and the top of the plants.
Illuminating plants not only gives them the photons they need to thrive, but it also creates an attractive display as part of your home decor. Maria prefers Soltech grow lights.
Maria adds to also be conscious of deciduous trees outside windows. In spring and summer, those trees block light to the window, but when the trees drop their leaves in fall, that same window will deliver more light to indoor plants, even though the days are shorter. You may have to compensate by pulling the plant stands farther from the window and the piercing winter light.
Know When to Keep Fertilizing and When to Stop
If a plant is not kept under grow lights in winter, fertilizer should be withheld because the plant is in that period of quiescence mentioned earlier. Don’t push the plant to grow when it wants to chill. Giving a plant fertilizer at this time is like asking someone to run a marathon when they’re just getting over the flu. Don’t push a plant to do something it’s not prepared to do. Resume fertilizing in the spring, when growth resumes.
Plants that are kept under grow lights or an exceptionally sunny window all winter should continue to receive fertilizer because they don’t experience quiescence.
“If you see new growth, if you see blooms coming, obviously support the plant,” Maria says. “Give it the nutrients that it needs to continue growing and to support it. If you notice your plant experiencing a little bit of quiescence, getting a little sleepy, actually kind of hibernating for the winter, if you don’t notice any new growth, then yes, taper off your fertilization.”
If you haven’t listened to my conversation with Maria Failla on winter houseplant care, you can do so now by scrolling to the top of the page and clicking the Play icon in the green bar under the page title.
How do you provide winter houseplant care? Let us know in the comments below.
Links & Resources
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