Jan. 14—This story was originally published in October 2020.
When the pandemic started, many people bought houseplants to brighten up their indoor spaces while also improving their home air quality. Winter is here, though, and new plant parents may not be prepared for the variety of issues houseplants face as the days grow shorter and colder, especially in Maine.
Some changes in houseplants are normal come winter, as the plants move into a more dormant state than in the sunny, warm growing season. But others need to be mitigated with an adjusted care plan.
"There's going to be leaf loss. They're adjusting for the season and it's normal. The days changing means our plants are changing," said John Sundling, owner of the Plant Office in Portland.
Here is what you need to know about helping your houseplants survive the winter in Maine.
Make sure your plants are getting enough light
The primary concern for houseplants in the winter — particularly in places with exceptionally short winter days, like in Maine — is access to sunlight.
"Some plants prefer more natural light than others and that can be challenging during the winter," said Melissa Higgins, wholesale manager at Sprague's Nursery in Bangor. "Without all the extra light, we also find that soil stays wet a lot longer during the winter months and can create many problems [like] root rot and fungus gnats."
Light is an issue for all types of houseplants, from ferns to succulents, though how each variety is impacted varies.
"If they're succulents, they can stretch out — it's called etiolation," said Lauren Tuell, founder and owner of Mainely Succulents in Orono. "They can lose their vibrant colors, [exhibit] stunting growth and lose leaves."
Houseplants struggling with the lack of light may need supplemental, artificial light to help get through the winter.
Sundling recommended purchasing compact fluorescent bulb lights in both cool and warm temperatures to simulate the broader spectrum of light for your houseplants.
"That's really the cheapest setup I've found," Sundling said. "There's surprisingly inexpensive grow lights that screw into regular fixtures. A little bit of extra light goes a long way with our long nights in Maine."
Keep temperatures and humidity consistent
Houseplants thrive best when the temperature and humidity of their environment is consistent.
Tuell said that the ideal temperatures for plants is between 60 and 75 Fahrenheit. To help keep temperatures consistent, not only is it important to keep plants away from drafty windows, but also from heating vents and radiators.
"A lot of people notice that there are drafts but they don't keep in mind that there's forced hot air in their house," Tuell said. "Their plants are getting that extreme shock of inconsistent temperatures."
Meanwhile, Tuell said that the ideal humidity for most indoor plants is between 40 and 50 percent, while she has found that winter humidity hovers around 10 percent in most indoor spaces in Maine.
"You're going to need to compensate for that," Tuell said. "The best course of action is a humidifier."
Your plants are likely to accumulate dust on their leaves throughout the course of the winter. Gently removing that layer or dust will help most plants to thrive.
"Show your plants a little extra TLC," Tuell said. "They'll not only look better but they will absorb sunlight better."
Succulents, however, are the exception to the winter dusting rule, Tuell said.
"They actually have a powder coating outside them that's sunscreen," Tuell said. "You would not dust off succulents."
Adjust watering habits
Most houseplants require less frequent watering in the winter. Some succulents may not require watering at all.
"In Maine, you're really best to avoid watering them for a few months, which sounds extreme," Sundling said "If you water them in the middle of the winter, they'll most likely get cold and wet and rot out."
Watering habits will also depend on your indoor environment.
"I don't like to recommend [that] you want to do weekly watering because your environment is different than mine," Tuell said. "I notice in the winter it's probably once every two weeks in my house, but once every week in the plant shop."
Your exact watering regime during the winter will depend somewhat on your plant.
"For plants like succulents and cacti, cut back on waterings to once every three to four weeks," Longfellow said. "For general houseplants, the rule of thumb is to water when the top few inches of soil feel dry."
Also, look out for root rot in soil that refuses to dry.
"The excess water creates a soggy environment which can damage the roots, but also makes it harder for the plant to receive oxygen," Longfellow said. "Being mindful of each plant's specific watering needs can help ensure success."
Make sure planters have drainage
In general, it is best to transfer plant containers during the spring and summer. However, a mistake that a lot of first time plant owners make is to pick a bad container with no drainage, or to keep a plant in a container even after it has outgrown it. Make sure your plant is in the best growing situation before winter comes.
"A lot of people have their succulents in a pot with no drainage for decorative purposes, [or they have] houseplants in ceramic pots with one little hole," Tuell said. "Assess your planters and see if you need to transplant anything out into something it's going to be happier in."
Tuell recommended using terra cotta pots because they are porous, and the aeration allows the soil to dry out faster.
"It's very affordable, it looks nice [and] you can paint it if it doesn't match your decor," she added.
If you have to transplant your plants in the winter, alter your watering to accommodate the change.
"If you transplant in the winter you will have lots of excess dirt that the plant hasn't grown into yet and this will cause extra moisture," Higgins said. "[Too] much moisture and you will have problems. Let plants dry out in between watering."
Watch out for winter pests
If you're bringing plants from outside for the winter, you should keep an eye out for pests brought in from outside, like spider mites.
"Spider mites love drier conditions," Sundling said. "The changing of the season can encourage pests to wake up in a way. Winter is when they're most susceptible to pests generally."
Mealy bugs are also a problem for succulents if the soil is too cool to dry out.
"They're fuzzy, white, cotton-looking bugs," Tuell said. "You might not even see them moving. If you see white spots and are wondering what they are, that's usually mealy bugs."
Tuell said that a simple mix of dish soap and water, or a store bought product like Neem oil, applied to problem areas will address most insect issues.
"I find that if I treat it with that for a week after it comes in, any eggs that were in the leaves or anything on the surface of the soil [are] gone," she said.
In general, Tuell said that understanding your specific plant's needs is one of the best ways to ensure that it will thrive through the winter.
"Do research on your specific plant, [and] you're more likely to put it in a place where it's going to thrive," Tuell said.