How to Grow Hollyhock
Alcea rosea
Hollyhocks are classic cottage garden biennials that produce towering spikes of flowers in their second year. Sow in summer in a sunny spot with well-drained soil, and stake stems early to prevent wind damage. They self-seed freely, so one sowing can establish a lasting colony. Watch for hollyhock rust and remove infected leaves promptly.
When to Start
Direct sow outdoors as soon as soil reaches 8°C — typically early to mid spring. Hardy enough to tolerate light frosts.
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Growth Stages
Approximate days from start
Care Essentials
- Feed with a balanced fertiliser in spring as growth begins, then switch to a high-potash feed monthly during the flowering season to prolong blooms.
- Hollyhocks are short-lived perennials often grown as biennials. Sow in summer for flowers the following year. Self-seeding freely — allow some seed to fall to maintain a colony.
Growing Conditions
- Min. soil temperature
- 8°C+
- Germination temperature
- 15–21°C
Pet Safety
- Direct sow
- —
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Spacing & Planting
| Plant spacing | 45 cm |
| Row spacing | 60 cm |
| Sow depth | 0.5 cm |
| Mature height | 200 cm |
| Mature spread | 45 cm |
Pests & Diseases
Pest Aphids
Identification: Clusters of small soft-bodied insects on shoot tips and flower buds, often accompanied by sticky honeydew and sooty mould.
- Blast off with a strong jet of water. Encourage predators by planting nectar-rich companions nearby.
- Spray with a dilute soft soap or neem oil solution, coating stems and the undersides of leaves.
- Apply a pyrethrin-based insecticide as a last resort, avoiding open flowers to protect pollinators.
Pest Slugs and Snails
Identification: Ragged holes in young leaves and stems, silvery slime trails visible in the morning, particularly on seedlings and newly transplanted hollyhocks.
- Apply a generous ring of sharp grit, crushed eggshells, or copper tape around the base of each plant.
- Use wildlife-safe ferric phosphate pellets (e.g. Slug Gone) according to label instructions.
- Metaldehyde-based slug pellets are now banned in the UK. Use only ferric phosphate or other approved alternatives.
Pest Hollyhock Weevil
Identification: Small elongated beetles feeding on leaves, leaving a characteristic shot-hole pattern; larvae may feed inside seed pods.
- Remove adults by hand in early morning when they are sluggish. Destroy infested seed pods.
- A contact insecticide containing lambda-cyhalothrin can be applied if populations are high, avoiding flowering periods.
Disease Hollyhock Rust Phragmidium malvacearum
Symptoms: Bright orange or yellow pustules on the undersides of leaves; corresponding pale yellow spots on the upper surface. Severely affected leaves turn brown and drop.
Treatment: Remove and bin all infected leaves immediately. Do not compost. Apply a copper-based fungicide or sulphur dust to remaining foliage after clearing.
Prevention: Ensure good air circulation by not overcrowding plants. Avoid overhead watering. Grow resistant varieties where possible and clear all debris at the end of the season.
Disease Leaf Spot Cercospora althaeina
Symptoms: Circular brown or grey spots with darker margins on leaves, sometimes with a pale centre. Spots may coalesce under heavy infection, causing leaves to yellow and drop.
Treatment: Remove affected leaves and improve air circulation. A copper-based fungicide can reduce spread in severe cases.
Prevention: Water at the base rather than overhead. Avoid planting in damp, shaded spots. Clear fallen leaves promptly at season's end.
Growing Conditions
| Min. soil temperature | 8°C |
| Germination temperature | 15–21°C |
| Base growth temperature | 5°C |
| Min. daylength to start | 10h |
| Photoperiod sensitivity | day neutral |
Frequently Asked Questions
- How far apart should I plant Hollyhock?
- Plant Hollyhock 45cm apart with 60cm between rows.
- Is Hollyhock frost hardy?
- Hollyhock is classified as Hardy.
