Text by Lori Broadfoot
Many of the colorful annual bedding plants gardeners purchase from greenhouses and department stores in the spring can be brought indoors as houseplants in the fall. Some specimens are at their most robust growth in the autumn, and you can extend your summer gardening glory by potting a few plants and setting them on sunny windowsills indoors for the winter. Unlike perennials whose roots can withstand freezing, annuals are plants, which in our climate, wouldn’t survive the winter. Some annuals have a natural life span of a few months where they come into flower, produce seeds and die back, but others, such as geraniums, actually grow perennially in their native environments, and if they are treated to a warm winter vacation can be re-introduced to the outdoors year after year. Over-wintering plants will also eliminate the need to purchase new plants in the spring.
Select plants that are free from disease and remove any dried leaves and stems. Inspect carefully for insects, which may be harder to treat once the plant is in the close confines of an indoor environment. A gentle shower with a garden hose should shake off any lingering pests.
Gently lift the plant from the ground with a garden fork taking care not to tear too many delicate roots, but most plants can withstand a little root pruning when being transplanted.
Choose a planter that is slightly larger around than the root ball of the plant. Fill the pot partially with a rich indoor-plant soil mix. Garden soil will likely not have the nutrients or the proper drainage for indoor use, and it may also harbor pests or diseases, so it’s best to use a soil mix specifically formulated for houseplants. Shake most of the garden soil from the roots and place the plant in the centre of the pot. Scoop soil around the roots, tap the whole planter on the floor a couple of times to shake the soil down and fill in around the roots. Air pockets may fill with water and drown roots. Fill the pot to the same depth as the plant was growing in the garden, or a little deeper. If the soil is too shallow surrounding the roots, the plant may become top-heavy and uproot itself as it gets taller.
Water well, and keeping the new transplants out of the direct sun for a few days, let them acclimatize to the indoors. Some leaves may be lost, or dry out at the edges as the plant settles in after the transplant. Don’t let the soil dry out completely, but don’t over water either; the roots need to breathe.
The following are a few plants we treat as annuals, but are suited to over-wintering indoors:
Shade-loving Coleus plants are perfectly suited to indoor life. They prefer moist, well-drained soil. Prized for their multi-colored foliage, they will thrive even in low-light conditions. They will, however become spindly if their stems aren’t pinched back regularly. Snip the stems at any point just above a ‘leave set’ or pair of leaves and this will force the plant to branch out, doubling the stems and leaves.
Coleus leaves are variegated in all shades of maroon, green, yellow, red and pink. Their blooms are insignificant, but the foliage will add striking interest to any window framing a scene of snow outdoors.
While Impatiens plants, also known as balsams, may appear delicate, they are among the most popular and hardy bedding plants in the world. Their blossoms are found in shades of red, pink, mauve, orange, rose and white, and as either single or double-petalled flowers, which resemble miniature roses.
Impatiens like moist soil; the plants will droop if left to dry out, and will do best in cooler temperatures. Impatiens will drop their petals as the flowers fade, so there is no need for dead-heading (removing spent flowers). Tip pinching will encourage the plants to branch out; this is best done following a period of blossoming as the plant enters a semi-dormant stage. As the plant leafs out and regenerates itself, new flower buds will form on all of the new branches. Most varieties of Impatiens are shade-tolerant, and will flourish in even curtain-filtered sunlight.
Geraniums should be cut back to about one-third their original height before transplanting, snip each branch close to a leaf joint. This will encourage the plants to branch out and keep them a manageable size for windowsill life. Geraniums need as much sun as possible, a south or west-facing window is best. Don’t be too concerned if they become “leggy” – the stems become long and the leaves small – as long as the roots are healthy, geraniums will bounce back to vigorous growth with the return of strong spring sunshine.
In the spring, after a winter of window-filtered light, your plants will need to be re-adapted to full-strength sunshine. Re-introduce your plants to the outdoor garden once the air has warmed by setting the pots in a shady, protected area for a few hours a day and bringing them back indoors every night. Gradually increase the time and intensity of the sun they receive, and once all danger of frost has past they can be replanted in the garden as you would newly purchased annuals.