Hollyhock (Alcea rosea) - How to Grow & Care Guide

Plant Snapshot

Common Name: Hollyhock
Latin Name: Alcea rosea
Hardiness Zones: USDA zones 3–8; plants die back in colder zones and may be shorter or perennial in warmer zones
Typical Height: 4–8 ft (120–240 cm)
Typical Spread: 1–2 ft (30–60 cm)
Bloom Period: Summer (main flowering in summer months)
Soil Preferences: Fertile, well-drained soil. Tolerates average soils. Poor drainage can lead to crown rot and shorter lifespan
Light Preferences: Full sun for best flowering. Tolerates light afternoon shade but may be leggier and flower less
Toxicity: Not widely listed as highly toxic to pets but ingestion can cause mild gastrointestinal upset. Sap or handling may cause skin irritation in sensitive people; verify with poison control for definitive guidance
Propagation: Seed is primary method. Can be grown as biennial sown autumn or spring. Some cultivars can be propagated by division or root cuttings

Key Facts

Biennial or short-lived perennial
Tall erect flower spikes commonly 4–8 ft (120–240 cm)
Spread commonly 1–2 ft (30–60 cm)
Prefers full sun
Flowers in summer on tall racemes
Prefers fertile well-drained soil
Attractive to bees and other pollinators
Most commonly started from seed

Hollyhock (Alcea rosea) is a tall biennial or short lived perennial grown for showy summer flower spikes. It performs best in full sun and fertile, well drained soil and is commonly started from seed.

Identification and habit

Hollyhock produces erect flower spikes on racemes and commonly reaches 4 to 8 feet tall with a spread of about 1 to 2 feet. Flowering occurs in summer and the plants are attractive to bees and other pollinators.

Where to grow and best uses

Use hollyhock at the back of a sunny border or along a fence where tall spikes are wanted for summer impact. Reported USDA hardiness ranges are zone 3 to 8 which affects whether plants behave as true biennials, short lived perennials or die back to the ground in cold winters.

Soil light and watering

Plant in fertile, well drained soil. Poor drainage increases the risk of crown rot and shortens plant lifespan. Full sun gives the best flowering while light afternoon shade will reduce bloom and encourage legginess. Keep soil evenly moist while plants establish and avoid waterlogging.

Planting and spacing

Seed is the primary propagation method and plants are commonly sown in autumn or spring. Seed timing influences whether individual plants flower in the first season or form a rosette and bloom in the second year. Space plants roughly 1 to 2 feet apart to match their typical spread.

After flowering and general care

Cut back spent flower spikes to tidy the bed and to encourage any late reblooming on some plants. Because many hollyhocks are grown as biennials expect to replant or allow reseeding for future seasons. Handle with care as sap can cause skin irritation in sensitive people.

Toxicity and safety

Hollyhock is not widely listed as highly toxic. Some sources note it is not listed as toxic to cats and dogs in the ASPCA database but ingestion can cause mild gastrointestinal upset and handling may irritate sensitive skin. Confirm pet safety with local poison control or a veterinarian for definitive advice.

Propagation

Start from seed for most reliable results. Some cultivars can be propagated by division or root cuttings. Choose the propagation method and sowing time based on whether you want blooms the first season or the next.

Frequently asked questions

How fast does Hollyhock grow?: Growth rate varies by climate and sowing time. Plants often form a rosette the first year and produce tall flowering spikes in the second year when grown as biennials. Mature height is commonly 4 to 8 feet.
When does Hollyhock bloom?: Hollyhock blooms in summer. Exact months vary by local climate and whether plants are grown as biennials or short lived perennials.
How should I space hollyhocks?: Space plants about 1 to 2 feet apart to allow for their typical spread and to help airflow around tall stems.
How do I propagate hollyhock?: Seed is the primary method. Some cultivars can be propagated by division or root cuttings. Sow in autumn or spring depending on whether you want first year flowering.
Is hollyhock safe for pets?: Hollyhock is not widely listed as highly toxic and is not listed in the ASPCA toxic plant database, but ingestion can cause mild stomach upset. Check with poison control or a veterinarian for definitive guidance.