Art in the garden: Overwinter container favorites indoors

If you took the time to create fabulous container gardens last spring, fall’s cooler temperatures probably cause you mixed emotions. While you may have grown tired of the routine watering, pinching and grooming required by container gardens, it is hard to say goodbye to the plants you’ve fussed over the last several months.

You needn’t resign yourself to relegating the beautiful tropicals and tender perennials to the compost bin when the first frosts threaten. Many plants can winter over inside and be ready to bloom again in your containers next year.

The trick to success is selecting the right candidates and knowing the appropriate conditions that will ensure their survival indoors.

Why go to the trouble of wintering over a plant? One reason is to guarantee that you will have an unusual specimen available next season. If you went to great lengths to find a special plant, you will probably find wintering over very worthwhile.

Also, some tropicals need a longer growing season to come into bloom than our northern Illinois summers provide. Plants like these deserve some extended hospitality in the form of a winter home indoors. The best reason may be the money you save next spring when you don’t have to repurchase your container favorites.

To be considered for winter relocation, a plant should be healthy, robust and compact. Plants hosting pests or disease have a poor chance of surviving the winter and will bring their troubles inside. Even seemingly pristine plants should be given a shower of insecticidal soap before taking up residence inside.

The physical stature of a plant is also important for several reasons. First, some leaf loss is inevitable when a plant leaves the high light and moisture conditions outdoors for life behind windows and drier air.

A full, compact plant can afford to lose some leaves and still be left with enough food-producing capability to sustain life, but a spindly plant will have a difficult time as it struggles with a few weak leaves.

Leggy plants that are otherwise healthy may be good choices if the plant variety is best held over as rooted cuttings. This technique is especially appropriate for fleshy-stemmed plants like coleus. Just cut some stems with a few leaves, pinch out the new, little leaves at the top, and put the stems in water. When they root in a week or so, pot them up and put them in a sunny window. Keep pinching new growth to keep plants compact or, if they get too leggy, just take more cuttings and start again.

If you plan to keep the plant in its summer container when you move it indoors, acclimate it gradually by transferring it to a shadier spot outdoors to get it accustomed to lower light levels. Have it spend nights inside for a couple weeks (and move it back outdoors during the day) to condition it to inside living.

Some plants overwinter best if they are allowed to go dormant in a frost-free environment. Woody, large-flowered tropical hibiscus thrives on relative winter neglect when protected from the cold. After moving them indoors, gradually reduce watering to encourage leaf drop. Once plants go dormant, reduce light and then water just once a month. A cool basement is an ideal site for this stage of the overwintering process. In March, move them to a sunny window, water thoroughly, and apply a weakened-solution of liquid fertilizer.

I love the beautiful blue blooms of Agapanthus blooming in my containers. I overwinter them by removing all their foliage before bringing them back in the house, and then store them in the basement. I lightly water them once or twice all winter. By the end of March, they are sitting in south-facing windows enjoying the resumption of water and fertilizer.

Most plants that will spend the winter indoors must be brought in before the first frost nips their leaves, but there are a few exceptions. The foliage of Cannas and Dahlias should be allowed to die back in the container. After a hard frost has killed the foliage, cut stalks off just above the soil and store pot inside in a lowlight, frost-free area. Water only occasionally while dormant. In March, move them to a sunny window and resume watering and fertilizing.

Some plants keep their foliage and may even flower for you indoors. Mandevilla are quite content sitting in a sunny spot with high humidity. Notorious for spider mites, make sure you inspect them thoroughly before bringing them in and keep an eye on them. Even though your Phormium doesn’t bloom, it will perform nicely as a houseplant in a sunny window.

Instead of saying goodbye to those tropical plants that have performed so beautifully for you this past summer, consider bringing them indoors for the winter. They’ll reward you next summer with another round of bountiful blooms.

ŸDiana Stoll is a horticulturist and the retail manager at The Planter’s Palette, 28W571 Roosevelt Road, Winfield. Call (630) 293-1040 or visit planterspalette.com.