How to grow hollyhock
Overview
Hollyhock (Alcea rosea) is a short-lived herbaceous perennial or biennial grown for its tall spires of large, showy flowers. It is a classic cottage-garden plant that adds vertical interest to borders and thrives in full sun with good air circulation.
Varieties
- Alcea rosea 'Chater's Double' — Fully double, ruffled flowers in a range of colours; popular in Australian cottage gardens.
- Alcea rosea 'Nigra' — Striking near-black flowers; a dramatic choice for borders and cut flowers.
- Alcea rosea 'Majorette' — Dwarf variety (60–80 cm) ideal for smaller gardens and pots; good for windy sites.
- Alcea rosea 'Peaches 'n' Dreams' — Soft peach and cream flowers; a modern favourite for pastel colour schemes.
Soil Preparation
Hollyhock prefers slightly acidic to neutral soil (pH 6.0–7.0) that is rich in organic matter and well-drained. Add compost or well-rotted manure before planting. Avoid heavy clay that stays wet, as it promotes root rot and rust.
Growing Guide
Plant hollyhock in full sun with well-drained soil enriched with organic matter. Space plants 45–60 cm apart to allow airflow and reduce rust. Sow seed directly in late summer or early autumn for spring flowers, or in spring for summer blooms. Stake tall varieties before they reach 1 m, using a single strong stake or a tripod.
Sowing
Sow seeds 6 mm deep, 30 cm apart, in seed trays or directly in the garden. Germination takes 10–14 days at 15–20°C. Transplant seedlings when 10–15 cm tall, handling carefully to avoid root disturbance. Direct sowing is easiest for this plant.
Care
Feed with a balanced slow-release fertiliser in early spring and again after flowering. Cut back spent flower stalks to encourage a second flush; remove old foliage in autumn to reduce rust spores. Stake tall stems before they reach 1 m to prevent wind damage.
Companion Planting
Hollyhock pairs well with other tall cottage plants like delphinium, foxglove, and lavender. Avoid planting near roses or other Malvaceae to reduce shared rust and aphid problems. Good as a backdrop for lower-growing perennials.
Common Pests & Risks
Rust (Puccinia malvacearum) is the main disease, causing orange spots on leaves; remove infected leaves and improve airflow. Aphids and caterpillars can attack new growth; spray with neem oil or insecticidal soap. Avoid overhead watering to reduce rust spread.
Troubleshooting
Yellow leaves with orange spots: rust fungus — remove infected leaves, improve airflow, avoid overhead watering. Stunted growth and curled leaves: aphid infestation — spray with neem oil or insecticidal soap. Tall stems flopping: lack of staking or wind damage — stake early and use a tripod. Poor flowering: too much shade or nitrogen — move to full sun and reduce fertiliser. Seedlings damping off: overwatering or poor drainage — use well-drained soil and water sparingly.