How to winter over hollyhocks in the garden? That depends on your USDA hardiness zone. Hollyhocks are often treated as annuals in cooler climates, because even with ample winter protection, the plant may not survive the winter. If you live in a cold winter climate and you want to have continual hollyhocks in your garden every summer, allow a few blooms to die on the plants so the plant can re-seed itself. This China native is an abundant self-seeder.
If you live in the more temperate climates of USDA Zones 5 and above, you can give your plants a bit of tender loving care in autumn, and the hollyhocks will regrow the next spring. It is possible however for the plants to survive up to zone 3 with care.
Cutting Down Hollyhocks
Cut hollyhocks in preparation for winter after the leaves and stalks turn brown after the first frost. Use a pair of garden shears or pruners and cut the stalks nearly to the ground, leaving only 1 to 2 inches of stems remaining. Throw the stalks in your compost bin.
A Word About Rust
Unfortunately, hollyhocks are susceptible to rust, especially in cooler, moist climates. If the plants show any sign of rust, cut the stalks to the ground, then place the stalks in a garbage bag and dispose of the bag in the trash. Never place affected plant matter on your compost pile. To recognize rust, watch for yellow spots to develop on the leaves during early summer. As the rust gets worse, the spots will turn from yellow to red, and will soon be transmitted from plant to plant.
To avoid rust, be sure your hollyhocks get plenty of air circulation. Don’t plant hollyhocks too close together. Be careful not to water excessively, as rust can develop as a result of soggy, damp soil. If you notice the beginning of rust during the summer, pull the affected leaves off the plant immediately. Always water hollyhocks early in the day so any excess moisture will dry by the time the temperature drops in evening. Water at the base of the plant to keep the foliage dry.
Apply a 3 to 4 inch layer of mulch over the hollyhock plant. Use an organic mulch such as straw, compost, pine needles or bark chips. Be careful about using lightweight mulch such as dry leaves, as the leaves can blow off the plants, leaving the roots unprotected.
Rake the mulch off the tops of the plants when new shoots poke up through the mulch in spring. Leave the mulch to the side of the plant for a few weeks so it can be quickly raked back over the hollyhocks in the case of a sudden springtime cold snap. When you’re finished with the mulch, spread it on your flower beds or throw it on the compost pile. Give the hollyhocks a running start with a dose of balanced granular fertilizer after you remove the mulch in spring. Do not fertilize over the winter.
Knowing how to winter over hollyhocks when gardening is essential for maintaining this plant from year to year. There is no reason to lose your beautiful hollyhock blooms.