By Sam Wasson
Updated Dec 15, 2022
When the winter months arrive, gardeners face a nasty reality: All those carefully cared for plants will quickly wilt and perish. Even especially tender perennials and bulbs can die if exposed to freezing temperatures. Thankfully, by overwintering plants inside your home, they can survive the onset of the deadly winter chill. If you’ve never heard of overwintering, this article explains how it works and how you can overwinter different species of plants.
Overwintering is the process of bringing your plants indoors so they can survive the frost and extreme cold of winter. Doing this ensures that the more fragile perennials and bulbs continue to thrive while saving a little money on annuals next year. Some plants, like geraniums and hibiscuses, are easy to overwinter, becoming house plants once inside. Others, like aloe vera, dahlias, and lilies, enter a dormancy period, shriveling up and becoming inert until next spring.
The exact process for overwintering your plants varies depending on what kind of plants you bring indoors. Here is a quick rundown of how to overwinter annuals, perennials, and bulb plants. Remember that certain plants, such as particularly fragile (tender) species like alocasias or marigolds, require special care compared to other plants.
Overwintering annuals can be a mixed bag, with some plants responding better than others. Most will look unhealthy during this process, losing their leaves, drooping, and obtaining a sickly appearance. However, some species are especially apt for overwintering, such as large annuals like geraniums, impatiens, coleus, and calibrachoa.
Interestingly, many of these species are “tender perennials” and can survive year-round under ideal conditions. Most bedding plants, like petunias and snapdragons, don’t overwinter well and are prone to dying off. Furthermore, these plants are abundant and cheap to replace, so overwintering them is typically not worth the time and effort.
The most important part when safely and correctly transferring annuals is getting the timing right. If you pot them too early, they’ll miss out on valuable nutrients that they typically begin stockpiling as winter makes its appearance, making them weak and prone to death. Wait too long, and the low temperatures will kill them outright. The trick is potting them at the first signs of a light frost — this is when they begin to produce extra nutrients for surviving the winter.
Next on the to-do list is trimming and prep. Before you remove and pot your annuals, remove all dead greens and wilting flowers. During this step, look for any insects or mold growth on the plant.
Specific pests to look out for are spider mites, aphids, and grubs within root systems. These kinds of pests love to hitch a ride indoors to wait out the cold weather, a process also called overwintering for insects. If you spot any infected portions, remove them promptly before potting. Once you’ve prepped your plants, you’re free to place them into a pot – be sure to consider your plant’s specific potting needs during this process.
Once the plant is ready to come indoors, pick a location with a good amount of sun. Your best bet is a spot adjacent to large windows, ensuring the plants get the most direct sunlight possible.
They’ll become houseplants during the winter and, even in the best condition, will begin to look “droopy” as the months go on. This sickly appearance is the result of them going into a dormant state. Dormant plants are still alive but reduce energy usage and stop producing new growths. As such, you won’t need to water them as much or fertilize them until the beginning of the new season. Once spring begins, they’ll start sprouting new growth and begin recovering from their dormancy period.
Typically, you won’t need to overwinter perennials. These are hardy plants, built to survive the long, colder winters to pop up anew come springtime. However, you also may have some potted perennials that you never got around to planting, which, if planted late in the season, won’t have the time to grow and establish themselves enough to survive the winter. In this case, you’ll want to overwinter these still-potted perennial plants.
There are a few ways to overwinter potted perennial plants, and they’re all relatively simple. Since perennials are hardier than annuals, there is less muss and fuss about timing and special care. Here are all the major ways you can overwinter perennials left in their pots:
Maintaining perennials while they overwinter is extremely easy. Since they go into a full state of dormancy, the most you’ll have to do is water them once every two to three weeks. If the temperature rises above 40ºF, the plants will begin to wake up. If this happens, you’ll need to bring them indoors and water them periodically until temperatures drop again.
The last kind of plant you can overwinter is tender bulbs. Tender bulbs are plants that grow from thick, rootlike storage structures. Some examples are tubers, corms, rhizomes, some true bulbs, and thick roots. Unlike most true bulbs, tender bulbs can’t survive the harsh, cold temperatures of winter and will die if not overwintered. Common tender bulbs that gardeners like to bring indoors include:
To begin overwintering tender bulbs, dig them up after the first frost. The exception to this rule is if your area is prone to heavy or abnormally cold frosts, as the temperatures may be strong enough to penetrate the soil and damage the bulb. The purpose of this is to allow the frost to kill off the foliage of the bulb, which begins the dormancy process.
Once the foliage of the bulbs has dried up and died, you can begin digging. The timing here is vital, as waiting too long to pull the bulbs carries the risk of bacteria getting in from the recently dead stems. Dig the bulbs carefully from the soil while trying not to cut or damage them, as these wounds can lead to rot and bacteria later on. Many tender bulbs will be clumped together in a large mass when growing. Try your best to separate them without causing overt damage — separating bulbs from the mass helps prevent mold growth and aids in curing.
Once the bulbs are up, clean them off and carefully inspect them for any signs of rot, discarding any that are infected. During this process, clip off any remaining stems.
Next, you’ll want to find a place for your bulbs to dry out or cure. Find a dry location devoid of direct sunlight with a constant temperature of 60ºF to 70ºF. Most bulbs only need to cure for one to three days, but some species need much longer, so always check the specifics of your bulbs before curing.
Once cured, place your bulbs in storage for overwintering. Inspect them one final time for any rot or pests, then find a dark, dry location with a temperature of 35ºF to 45ºF for storing them.
Popular choices are unheated garages, basements, and sheds. It’s best to store bulbs in a breathable container (like a cardboard box) between thin, two- or three-inch layers of dry, absorbent material like sand, peat moss, sawdust, mulch, wood shaving, or shredded coconut fibers. Make sure your bulbs don’t touch; if one grows rot, physical contact can spread it to the others.
While you can overwinter most large plants, a few popular mainstays exist in the gardening community. Here are a few of the most popular plants that gardeners love to overwinter, like pepper plants and elephant ear plants, and how to best overwinter them.
Pepper plants are one of the most popular picks to overwinter in most vegetable gardens. However, they require special care when overwintering, and prepping them is a little more complicated.
You’ll want to prep pepper plants before the first frost kicks in. Try to aim for a time when nightly temperatures are just starting to hit 40ºF. Start by assembling an adequately sized pot filled with fresh, moist soil. Next, prune all the branches and stems, leaving only a few nodes off the main stalk. Then, remove the root ball and clean it of any excess soil, checking for rot and pests while you do so. Place the plant into the new pot and add soil until its roots are entirely covered.
Now you can look for a good spot for your peppers to overwinter. Unlike other plants, peppers prefer a relatively warmer location, preferably somewhere around 50ºF to 60ºF. Once they’re set, cut back on your watering to once every three to four weeks. Your peppers should be ready for return in early spring.
Elephant ear is a popular tropical plant from Asia that doesn’t react well to chilly winters in the United States. If these plants don’t come indoors in fall, the frost will completely wipe them out. Thankfully, you can overwinter them by turning them into houseplants, similar to the process we discussed for annuals.
You’ll want to begin bringing your elephant ears indoors at least two weeks before the first frost in your area. If these plants are already potted, you can bring them directly inside after a quick pest and mold check. Otherwise, you’ll want to dig them up and place them into an appropriately sized pot filled with moist soil.
As houseplants, elephant ears like locations with bright, indirect sunlight, high moisture, and moderate temperatures (50ºF to 60ºF). Like annuals, once indoors, they’ll go into a semi-dormant state and require less watering; once every two to three weeks should do. You can also overwinter elephant ears as tubers, using the same process for bulbs discussed above.
Overwintering plants is a reliable way to save money and keep your favorite garden staples alive as winter approaches. Whether you’re a master gardener or a green-thumbed beginner, there’s something truly satisfying about watching plants you’ve kept in your home sprout up again come growing season. While some plant species don’t react well to overwintering, many can safely survive the winter indoors.
If you’re looking to start overwintering, it’s always a good idea to look into your USDA hardiness zone, also known as a frost zone or growing zone. Developed by the USDA and last updated in 2012, hardiness zones are scales that show the major regional climates of every portion of the US. They can help you determine which plants best suit your area and your average expected frost date. Using this tool, you can plan exactly when to pull your plants and begin potting them or bringing them indoors for winter.
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