How To Protect Cosmos Plants From Being Wiped Out By Winter Frost

Cosmos are a springtime garden favorite, loved for their symmetrical, round blooms in a variety of colors. The genus is home to around 35 perennials and hardy annuals. If you want your cosmos to survive through the winter, you'll want to make some preparations. Cosmos are typically perennial down to USDA Hardiness Zone 3, but exceptionally harsh winters can damage their foliage. Cosmos younger than 2 years are especially vulnerable to winter frosts.

These plants are hardy, so it's likely that your mature cosmos will bounce back after frost damage. However, if you want to set them up for a productive spring and keep them looking well cared for, frost protection is in order. The key to frost-proofing cosmos is maintaining warmth throughout the plant. You can do this by adding insulation to the ground and sheltering the plants from harsh winds. You can also move your plants indoors or into a greenhouse for the winter.

Insulation is essential for protecting outdoor cosmos plants from frost. A light layer of mulch over your flower beds helps lock in heat and keep frost at bay. Straw, shredded leaves, and pine needles make excellent mulch for insulation. Using cold frames or greenhouses can also prevent frost from accumulating on your plant beds and protect your cosmos from icy winds. These methods are especially helpful for protecting young plants. In the case of sudden frosts or temperature drops, cover young cosmos with a frost cloth or other light cover.

If your cosmos are planted in pots, you're in luck. Simply overwintering your potted plants indoors is enough to keep them looking lush and healthy. If they're planted in the ground but you still wish to bring them inside, you can repot them. When repotting, acclimate the plants slowly to their new environment and place them in a well-lit area. A bit of work and protection now ensures your cosmos greet the new season stronger, brighter, and more beautiful than ever.