When winter comes, many gardeners give up on plants that are killed by frost. But by bringing in some “tender” (not winter-hardy) plants typically grown outside, I can enjoy them in the winter and sometimes keep them alive for years.
First a word on terminology. Annuals are plants that, in their native environment, go through their entire life cycle in one growing season. They sprout from seed, flower, make more seeds, and die over the summer. Tender perennials are plants that, in their native environment, live for more than a year. In cold-climate gardens, they are killed by below-freezing temperatures.
Tender perennials can often be saved by bringing them indoors for the winter. Annuals, in general, cannot.
I grow tender plants I plan to bring indoors in pots, to make it easier to move them inside. That way, I won’t be digging up my garden beds just before a hard frost. Tender plants grown outdoors in the summer usually fare best indoors near a very sunny window. There may be an adjustment period in the fall when the plant struggles or loses leaves.
Grown for its colorful leaves, coleus often gets treated like an annual but is a tender perennial. If you grow unusual varieties of coleus from seed, or bought for a fancy collection of plants from a grower such as White Flower Farm, you might want to consider bringing your coleus plants indoors. Or you could bring it inside, because you’d just like a few extra house plants with interesting leaves.
Coleus doesn’t need a lot of light. I grow mine in a north-facing window at home, and I kept a coleus plant in my windowless office at work. It did just fine under the office flourescents. But it’s doing even better now that I have an office with a window.
Cold Northern winters kill basil, parsley, and rosemary. By growing these herbs in pots and moving the pots indoors to a sunny window, I can keep the plants growing for a few extra months, and sometimes even longer. Because I have a good-sized plant collection, I don’t save my parsley plants for their looks. I just like having fresh parsley in January.
Some herbs, such as rosemary and sweet bay, will live for many years if brought indoors for the winter. Because these are woody plants, potted rosemary and sweet bay can get quite large, given enough time.
Yes, most Americans think of the humble geranium as an annual. But they are actually tender perennials. My friend has been growing her geraniums indoors for many years, and they have gotten to be 3 or 4 feet tall. Mine are so far smaller, about 2 feet.
Don’t expect many blossoms from your geraniums during the winter. Do place them in a sunny window and provide humidity. My geraniums often lose quite a few leaves when they first come inside, but they recover.
Flowering Annual Baskets
In the spring, my garden center sells big baskets of flowering “annuals” for $20 to $30 apiece, and it’s hard not to buy a pretty basket for the back yard. Not all the plants they sell in baskets are tender perennials, suitable for growing indoors, but some are.
If you choose the right basket (a tender perennial) in the spring, you can enjoy your plants in the winter months. Look for fuschia, wandering jew, and other tender perennials. Even impatiens will last a while past the first frost if brought indoors.
If the hanging basket is porous or large, you might choose to repot some or all of the plants into smaller, or different containers.