Any cold-climate gardener who has ever visited California or Texas in winter can’t help but be jealous of the gorgeous pots, window boxes and planters overflowing with spectacular plants. Those lucky gardeners can even grow entire trees in containers without too much worry about hard freezes completely zapping their plants or shattering their containers.
Enjoy big, beautiful geraniums like these without the annual investment by bringing them inside to overwinter.
Photo Credit: Sam Spiro/fotolia.com
You can grow small trees in containers year after year no matter where you live – you just have to choose your tree carefully and provide adequate winter protection.
Photo Credit: Whitechild/fotolia.com
While these potted boxwoods aren’t likely to survive a winter freeze, you can bury them in the ground or bring them inside to a cool place to help them see another spring.
Photo Credit: Save The Moment/fotolia.com
Thriving outdoor container annuals can easily be turned into houseplants that spend the winter indoors.
Photo Credit: Mark A. Miller
In colder climates (USDA hardiness Zone 6 and colder – roughly the northern third of the US), subzero temperatures are tough on plants and containers. The bitter cold freezes container soil solid, ending the life of any plants within, and the freeze and thaw cycles often reduce pots to a pile of shards in just one winter.
Despite these cold, hard facts, Northern gardeners can still enjoy beautiful, bounteous container plants filled with rosemary, roses, figs, dwarf fruit trees, citrus trees, jasmine, hibiscus, gardenia, oversized geraniums and bougainvillea. The trick is to do it right. Here are some tips to get you started:
Choose the right container. Look for cold-proof pots that you can leave outside year-round. Terra-cotta, ceramic and concrete containers are not good selections because they absorb moisture, which expands when frozen. This cracks or shatters the pot. Instead, look for wood or metal containers that can handle a freeze with minimal effect.
Fiberglass and other plastic-like containers are a mixed bag in terms of winter endurance. Cheaper, more brittle plastics will freeze and crack over time. Fiberglass, resin and other upscale plastic-type containers will last the winter, but their colors tend to fade over a few years, making them lose their realistic look.
Try some overwintering strategies. Small evergreen trees and shrubs look great in pots – especially flanking either side of a doorway. Planted in the ground, they’d likely grow, thrive and last for years. But they just can’t survive the cold winter freeze in pots because their roots aren’t protected as they otherwise would be in the ground. So what are your options?
Well, you can think of your potted plants as annuals, even if they aren’t. Keep them around for a year – enjoy them while they thrive and add twinkling lights to them around the holidays. Just be prepared to replace them next year, because more than likely, the needles will brown and fall off when the spring thaw comes. But hey, for about 12 months, you will have enjoyed a great plant or two.
Or, if you don’t like the idea of replacing your container plants annually, try sinking the pots in the ground before winter arrives. Many selections, like shrub roses, are hardy to -20 degrees F when planted in the ground because the surrounding soil insulates the plants’ roots from freezing. Just dig a hole (or a trench for several plants) several inches deeper than the depth of the pot. Set the container in the hole, and use mulch and partially decomposed fall leaves (or any material that’s dense enough to stay in place but allows some air and moisture in) as backfill. And be sure to bury the plant deep enough to cover its vulnerable crown (the point near the bottom of the plant where the species was grafted onto the rootstock).
A good spot to “plant” your pots is next to your compost heap, since it’s usually a messy workplace anyway. Some partially covered plants won’t create a problem, and that partially decomposed compost is perfect for filling the holes anyway. While there are no absolute guarantees your containerized plant will survive through winter, chances are it will – and you’ll have a nice plant, all potted and ready to go come spring. Just wash it off and set it out (or stick it inside a more decorative container to dress it up).
Put your plants in cold storage. Another way to try to save your container plants is to pick them up and move them inside to a sheltered location where the plants will get a “fake” mild winter that puts them into dormancy. Depending on the type of plant, bring it indoors to a place that’s so cold the plant won’t actively grow, but warm enough that it won’t be injured. For most selections, that means not letting the temp get below freezing or above 50 degrees F – about the temperature range of a refrigerator.
Bring your plants indoors to a warm place. Many plants in colder climates thrive if they get to spend their summers outdoors and their winters inside in a sunny spot. This is also like faking winter – only one that’s in a very warm climate like California or Florida, where winter daytime temperatures can get into the 70s and 80s. Citrus trees are great candidates for this type of care. Put them on a deck or patio in summer, then bring them indoors, where it’s warm and sunny, when the seasons change – and before the first frost hits. They’ll often reward you with small fruits in the dead of winter.
So really, container gardens are practically limitless no matter where you live – even in the frozen North. Just be smart about the containers you use, the plants you select and how you care for them. With some experimentation and resourcefulness, you’ll be able to enjoy all kinds of potted beauties – indoors and out – year-round!