Hollyhocks (Alcea rosea) are biennial or short-lived perennial plants that naturally adapt to colder climates by entering a dormant phase during winter. As temperatures drop, their above-ground growth dies back, while the root system remains alive underground. This survival strategy allows them to conserve energy and re-emerge in spring. However, in extremely cold climates, additional protection may be needed to ensure their longevity and health.
The best time to prepare hollyhocks for winter is after the first hard frost, when the plant has naturally begun to senesce (age and wither). This typically occurs in late fall. At this stage, the plant has stopped active growth, and its energy is focused on the roots. Preparing too early may disrupt this process, while delaying could expose the plant to frost damage.
After the first frost, trim the hollyhock stems to about 6 inches above the ground. This reduces the risk of disease and pest infestations, as decaying foliage can harbor pathogens. However, avoid cutting too close to the crown (the base of the plant), as this may damage the growing point. Leave some stubble to help trap insulating snow or mulch.
Remove all fallen leaves, spent flowers, and other plant debris from around the hollyhocks. This prevents fungal diseases like rust, which commonly affects hollyhocks, from overwintering and reinfecting the plant in spring. Dispose of diseased material away from the garden—do not compost it.
Apply a 3-4 inch layer of organic mulch (e.g., straw, shredded leaves, or wood chips) around the base of the plant after the ground has frozen. Mulch acts as insulation, preventing freeze-thaw cycles that can heave roots out of the soil. Avoid piling mulch directly against the crown, as this can promote rot.
First-year hollyhocks or those grown in containers are more vulnerable to cold. For potted plants, move them to an unheated garage or sheltered area. For young plants in the ground, consider covering them with a frost blanket or burlap after mulching to provide extra protection from wind and extreme temperatures.
While hollyhocks are dormant, they still require occasional moisture. In dry winters, water the soil lightly on warmer days to prevent desiccation. Avoid overwatering, as soggy soil can lead to root rot. Snow cover often provides sufficient moisture, but supplemental watering may be needed in snow-free periods.
In late winter or early spring, as temperatures begin to rise, gradually remove mulch to allow the soil to warm. Inspect the crown for new growth and clear away any remaining debris. This ensures the plant can emerge without obstruction and reduces the risk of mold or pest issues.
