Preserving Potted Plants in Winter

Gardening by the Yard : Episode GBY-724 -- More Projects »

"It's no secret that I love container gardening," says master gardener Paul James. "I have no less than 91 different potted plants scattered all around my property." His containers house everything from annuals and perennials to culinary herbs, tropical plants and even some good-sized trees and shrubs. James explains some helpful ways to care for your container plants year round.

Figure A

Figure B

What's a gardener to do when a hard freeze is just around the corner? With limited indoor space available for over-wintering container plants, James makes room for his tropical plants first. Over the years, James has determined which plants will survive in which indoor location provided they receive plenty of indirect light. Some of these plants include gingers (figure A), which often continue to flower indoors. James relocates some of his miniature water gardens indoors (figure B) and has successfully over-wintered bananas indoors, too. Even his giant Peruvian cactus has flourished by enjoying two winters in a sunny corner of his den.

Figure C

"But I haven't always been that successful with tropical and subtropical plants," says James. For example, this strobilanthes looks fine now (figure C), but indoors it usually drops its leaves after a few weeks. That's because some plants-- especially large, herbaceous ones and those with woody stems--simply can't handle the abrupt move indoors. Unless, of course, indoors refers to a fancy climate-controlled greenhouse. Plants may react to different changes in conditions such as lack of light, insufficient humidity and stress caused by indoor pollutants. But sometimes plants adapt better if you start them indoors as young plants, rather than mature ones.

Figure D

To start your own indoor versions, snip off a 6-inch section of the terminal growth from the plant. Strip off the lower leaves, and place the cutting in water, sand, or potting soil until it begins to root. Depending on the plant, young roots will likely begin to form within a few weeks. When the roots develop a healthy system such as these coleus cuttings (figure D), then they are ready to plant into a pot.

Figure E

James is over-wintering bamboos indoors for the first time, specifically clump-forming bamboos in the genus Bambusa. While bamboos make beautiful additions to a landscape, they are hardy to only around 15 degrees F. "Bamboos make excellent houseplants," says James, "and I know many gardeners who keep them indoors year round" (figure E).

Several culinary herbs over-winter in the house well, especially if they get more than five hours of sun every day, or if you have fluorescent lights shining on them for up to 14 hours a day. "And let me tell you folks," says James, " there's nothing like snipping a bunch of fresh herbs in the dead of winter to add depth to a brazed meat dish or brighten up a big bowl of pasta."

Figure F

Figure G

However, not all herbs are created equal when it comes to indoor gardening. Among the easiest of herbs to move indoors are chives, thyme, oregano, basil and sage. Mint and parsley (figure F) will do fine for a while, although both prefer cool conditions.

Rosemary is likely the most difficult herb to keep indoors (figure G), but with proper care it should last a few months. James recommends misting rosemary often and taking extra care not to over-water. Over-watering is the quickest way to kill culinary herbs indoors. To avoid killing your plants with too much care, allow the top two to three inches of soil to dry completely between waterings, and use room-temperature water.

Figure H

Figure I

Depending on where you live, your potted perennials may survive the winter outdoors without any protection. "That's exactly what I do here in my Zone 6 garden," says James. "I just leave them out in their pots, don't pay much attention to them at all, and every spring they come back with a vengeance." Some of James' powerful perennials include daylilies, sedums, coreopsis (figure H), society garlic, ornamental grasses. The perennials die back to soil level during the winter months, and during that time, the only attention they get is an occasional soaking when it's especially dry out. A woody plant, this pine (figure I), also does fine in its container all winter.

Figure J

If you live in an area of the country where winters are especially severe, take more protective measures. The simplest is to take a perennial out of the pot and plant it in the garden during early summer or late fall. Another method is to bury the plant--pot and all--in the garden, and then remove it the following spring. You can also insulate the plant by surrounding it with a layer of mulch (figure J), straw or shredded leaves.

Figure K

An unheated garage may be another place to over-winter many of your potted plants especially if the temperature of the garage rarely drops below freezing. If your garage gets much colder than that, take additional measures by wrapping the root ball in plastic bubble wrap (figure K).

"Getting your container plants to survive the winter is gratifying, and it saves you from having to purchase new plants for the patio every year," says James. "Ultimately, getting your plants to survive the winter indoors is all about experimentation, and believe me folks, not all my experiments have ended happily. But even if only half of my plants survive indoors, that's better than none at all, right?"

Also in this Episode

Gardening by the Yard : Episode GBY-724
•	Preserving Potted Plants in Winter
•	Good Drainage Is the Foundation of a Great Landscape
•	Edible Flowers
•	Clay Pot Repair

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