How to Overwinter Plants: Geranium, Begonia, and More!
Keeping Plants Over Winter
October 20, 2021
Well before fall frost arrives, it’s time to start thinking about overwintering some of your favorite flowering pots and plants! From geraniums to tropical bulbs to herbs, see which plants can overwinter and how to keep certain plants growing year after year.
What is Overwintering?
If your flowering plants or herbs are still going strong when cool weather arrives, it can be dismaying to know they’ll die! However, many of these plants can “overwinter.”
Overwintering plants simply means bringing plants indoors or giving them shelter from cold weather, wind, and snow.
Some plants can overwinter as houseplants. The most successful are: geraniums, Boston ferns, and tropical plants such as begonia, caladium, coleus, and hibiscus. For these plants, the general rule is to give them as much light and humidity as possible; keep away from heat ducts. Some will benefit from artificial light.
Other plants go dormant and can rest in your garage or basement. This is especially true of plants with bulbs, tubers, or corms, such as cannas, dahlias, and some lilies. For these plants, you simply cut back the foliage, gently dig it up, and store dried roots in a cool, dark spot.
Here is advice on overwintering some of our favorite plants!
How to Overwinter Geraniums
Even though most folks grow geraniums (Pelargonium x hortorum) as annuals, they are tender perennials that can keep growing with some help. Before the first frost (find frost dates for your region here), cut plants back to about 6 to 8 inches. Then lift the plants and cut back the roots. Put the trimmed plants in the smallest pots possible—containers just large enough to fit the roots. Fill the remaining space in the pot with regular potting soil. Keep the plants in the shade for a week and then place them in a sunny spot indoors. When new growth starts, cut off all the old leaves. Learn more about geraniums.
This culinary herb prefers life in a pot and can successfully survive as a houseplant from year to year. Before a frost in the fall, dig it up, plant it in a pot, and bring it indoors. Place it in a sunny window and keep it evenly watered. Mist the leaves frequently or place the entire plant in the shower and give it a good rinse once a month. The plant may start to look a little tired by March, but it will perk up once you return it to the garden. Dig a hole in the late spring, after all danger of frost has passed, and set the plant back into the soil. Learn more about overwintering rosemary.
How to Overwinter Roses
Roses need thick insulation to help them stay dormant. For those that are grafted, such as hybrid teas, make sure that their graft unions are covered with soil to insulate them from low temperatures. After a freeze or two, mound 12 inches of soil around the base of the rosebush.
Nongrafted roses, such as rugosas and antiques, don’t need much protection. Just mulch the ground around them with a couple of inches of straw or shredded leaves.
All climbing roses need to be protected. Pull down the canes, lay them on the ground, and cover them with at least 6 inches of soil. Mound soil around the plant base, too. If your winter temperatures go below –10°F, leave canes in place and insulate them with a thick covering of straw wrapped with burlap or old sheets.
Move your hibiscus plants into winter storage before the first fall frost. Check the plants for insects, especially whitefly, before you bring inside. It needs to stay in a spot with some light and temperatures warmer than 50 degrees F. Don’t worry if the flowers and leaves fall off! This is normal as your plant is going into dormancy. Water the plant, but only when the soil is dry. In the early spring, you can prune back any leggy growth, repot, and start fertilizing every couple weeks. Slowly get the hibiscus used to the outdoors once all danger of frost has passed. See more advice on our Hibiscus Growing Guide.
How to Overwinter More Tropical Plants
Many tropical plants grow from underground bulbs, corms, or tubers, including caladium, calla lily, canna, dahlia, ginger, and tuberous begonia. These plants are easy to overwinter. When nights drop into the low 40s or high 30s F, the leaves of plants will brown and begin to die. This is your cue to dig, or lift, them up to store indoors for the winter. (You can wait until after a killing frost to dig dahlias and cannas.)
Remove the dirt from the swollen portions of the roots and set them on newspapers in a shaded area or the garage to cure for a couple of days. Cut off the top growth and pack the bulbs, corms, and tubers in a box filled with dry peat moss or vermiculite. Store in a dark area where the temperature is between 35° and 50°F.
When spring arrives, plant again for another year of enjoyment. Bulbous tropicals will increase their numbers and produce bigger bulbs, corms, and tubers when they are saved from year to year in this manner. Read more about overwintering tropical plants.
Extra-Hardy Tropical Options
These plants can take colder temperatures than others in their class. The temperature given is what the plant can survive without protection. You can gain another 5 to 10 degrees of cold tolerance if you mulch heavily, plant in a sheltered area, and wrap plants.
To encourage your perennials, especially new plants, to go dormant and stay that way through the inevitable freezing and thawing cycles of winter, you may apply mulch of straw, leaves, or other organic matter after the first several hard frosts. If you mulch the ground too early in the fall, rodents may find the cozy layer impossible to resist and the mulch may also delay the ground from freezing solid. See our article on getting your perennial garden ready for winter.
How to Overwinter Trees
Protect a small tree or shrub from extreme cold and the uneven temperatures of freezing and thawing by surrounding it with a cylinder of snow fencing or chicken wire. Fill the space between the tree and the fencing with straw or leaves for insulation.
To shield a dwarf or young evergreen from winter damage, drive stakes into the ground at four corners around the plant. Wrap burlap or heavy black plastic around the stakes and secure it at the top, bottom, and center with stout twine.