Hollyhocks are a classic addition to many gardens, known for their tall, striking flower spikes. Understanding when and how to cut them back is important for their health, to encourage more blooms, and to manage their presence.
Understanding Hollyhock Growth Habits
Hollyhocks are generally categorized as biennials or short-lived perennials. Biennial hollyhocks typically establish foliage and root systems in their first year, then produce their tall flower spikes, set seed, and die in their second year. Perennial varieties can return for several years, though often for a limited lifespan of about two to four years.
Hollyhocks often appear perennial due to strong self-seeding. If spent flowers are left, they produce seeds that drop and germinate, leading to new plants and a continuous presence in the garden.
Cutting Back During the Growing Season
During the active growing and flowering period (April to July), deadheading involves removing spent flowers as they fade. This practice encourages the plant to produce more blooms by redirecting its energy from seed production into creating new flowers, often extending the blooming season. You can simply pinch or clip off the faded blooms before seed pods form.
Removing yellowed or diseased leaves throughout the growing season also benefits the plant. Hollyhocks are susceptible to rust, a fungal disease causing yellow or brown spots. Promptly cutting off infected leaves prevents disease spread and improves plant health. Dispose of diseased parts away from your garden to avoid spreading spores.
End-of-Season Cut Back
As the growing season concludes, typically in late fall or early winter, an end-of-season cut back prepares hollyhocks for dormancy. This pruning manages self-seeding, preventing unwanted new plants. It also aids disease prevention, especially for rust, by removing infected material that could harbor spores over winter.
For biennial hollyhocks, cutting the stalk to about 1 inch (2.5 cm) from the ground in early September may encourage another year of life. For both biennial and perennial types, the stalks can be cut back to a few inches above the ground after the last flowers fade or when the foliage turns brown and appears dead. This tidies the garden and clears space for new growth in the spring. If you want the plant to self-seed, allow the seed pods to mature and drop their seeds before cutting the stalks back.
Techniques for Cutting Back
Using clean, sharp pruning shears is important for all cutting tasks, whether deadheading or end-of-season cuts. Sharp tools make clean cuts that heal quickly, reducing plant stress. Disinfect pruning tools, especially when cutting diseased material, to prevent pathogen spread.
To disinfect tools, wipe or dip them in 70% isopropyl alcohol, which requires no prolonged soaking and is effective against most pathogens. Alternatively, use a 10% bleach solution, soaking tools for 10 minutes, then rinsing with clean water to prevent corrosion.
When deadheading, cut the faded flower just above a leaf node or side shoot. For end-of-season cuts, make a single, diagonal cut into each stem a few inches above the ground, taking care not to cut too low to avoid damaging the crown.
Post-Cutting Care
After cutting back hollyhocks, proper disposal of plant material is important. If parts were diseased, especially with rust, avoid composting as spores can survive and reinfect new plants. Instead, bag and discard them, or burn them away from the garden.
Watering is minimal in winter as the plant goes dormant. During the active growing season, ensure the plant receives adequate water, especially after significant pruning. Applying a layer of mulch around the base of the plant after an end-of-season cut, approximately 4 to 6 inches deep, can help protect the root zone from freezing temperatures over winter. Monitor the plant for new growth in the spring, gradually removing mulch as temperatures warm to allow for proper development.