Last weekend, I decided it was the end of the season for the two large flower container gardens that sit on each side by my front door. The most recent bout of wind decimated the large coleus plants and the beautiful petunias were finished flowering. Now the containers are empty because I have yet to decide whether to fill them with fall flowers, plant them with spring flowering bulbs or simply finish the cleanup process and get them ready for next spring.
I like planting frost-tolerant fall flowers in my planters to extend the season, but often wonder if their relatively short display of beauty outweighs the time and expense. While combinations of the typically available choices of mums, flowering kale and pansies can be attractive, they do not lend much versatility to fall container garden design. However, creative gardeners can use perennial herbs and flowers, ornamental grasses, shrubs and even frost tolerant vegetables in the planters for something different. The perennials that survive the winter cold can then be relocated to the garden next spring.
Better Homes and Gardens suggests using colorful coral bells (Heuchera), Heucherella, asters, grasses and sedges, kale, swiss chard, dead nettle (Lamium) and silver sage (Salvia argentea) in fall planters. Look through a vegetable garden catalog and check out the foliage of kale, Swiss chard, beets and lettuce. Their leaves can provide interesting color and texture, plus you can eat the fall crops. Also, the blue-gray foliage of garden sage (Salvia officinalis) and rosemary contrast nicely with purple-leaved kale and chard.
Before planting perennial and woody plants in containers, consider that they need to be watered regularly during the winter to keep the roots from drying out and dying.
If you decide to depart from the ordinary and plant perennial flowers, herbs or even shrubs, even plants hardy for our region (Zone 6) may succumb to winter cold. This is because the roots of plants in containers are subjected to colder temperatures than if planted in the garden. When planted in the ground, the surrounding soil insulates the roots, providing protection from severely cold temperatures. Roots are the least hardy plant tissues, making plants more susceptible to cold damage when planted in containers.
Several years ago, I planted two dwarf globe arborvitae in my front pots, and they survived a winter that was not excessively cold. However, the next spring I removed these shrubs from the planters so I could plant colorful annuals. Plus, I found it tiresome to water the containers during the winter.
Before planting perennial and woody plants in containers, consider that they will need to be watered regularly during the winter to keep the roots from drying out and dying. Also, these plants may succumb to winter cold, but if they do survive and you want to change your container garden display from year to year, they will need to be replanted in the landscape.
I am still in a quandary about what to do with my planters. There are so many possibilities. I am tempted to plant some traditional bright yellow mums along with the less conventional veggie garden kale, chard and herbs. I also like the beautiful variegated foliage of the many new coral bells and Heucherella cultivars. However, I also want to try planting bulbs. I need to make my decision soon before it’s too late to plant anything.
Marianne C. Ophardt is a horticulturist for Washington State University Benton County Extension.