It’s Thyme to … October


As we transition from summer to the cooling days of early fall, it’s time to begin putting our gardens to bed—while also thinking ahead to next year.

Tender perennial plants that can’t survive our Iowa winters must receive special care if we’d like to keep them around for next year. Dahlias, cannas, and gladiolus corms and roots should be dug and prepared for storage over the winter.

Gladiolus corms should be dug in early fall a month or so after they finish blooming and before a hard freeze. Cut the foliage off above the corms and allow them to sit in an airy location for two to three weeks to cure, after which you can separate the corms and store in a loose basket or bag over the winter in a cool, dry location at a temperature around 40°F.

JCMG volunteers cutting canna stalks back.

Cannas and dahlias should be dug after a hard frost and allowed to dry for several hours to a day. Dahlia tubers should be stored upside down in boxes and covered with vermiculite, sphagnum peat, or wood shavings, with the boxes stowed in a cool area 40 to 55°F. Canna rhizomes should also be stored in boxes, crates, or mesh bags between 40 and 50°F.

Collect seeds from your favorite annuals like zinnia, marigold, and poppies to sow next spring. Coleus and geraniums can be overwintered as cuttings or in pots indoors.

Houseplants and tender herbs also should be brought indoors before the weather gets frosty. When bringing plants indoors, be sure to inspect carefully for pests and disease.

It’s also harvest time! Pumpkins and winter squash should be harvested when their vines die back after frost. Be sure to harvest any remaining apples as well.

If you want to grow garlic or shallots the best time to plant them is late fall 3 to 4 weeks before hard frosts and the ground freezing. For southeast Iowa this would typically be the last week of October into early November. This will enable the bulbs/cloves to establish some roots before the coldest time of the year. After planting, cover rows with 4 to 5 inches of dried grass, chopped hay or leaf mulch to insulate during winter.

Though the season wanes, it is nevertheless time for planting deciduous trees and shrubs, as well as spring-flowering bulbs like tulips and daffodils that should be in the ground before it freezes.

Before you know it, chilly winter will arrive and you can enjoy the memory of your well-tended garden and know you’ve prepared it well for its seasonal sleep.