Ornamental · Malvaceae
Hollyhock
Alcea rosea
Tall, old-fashioned spires of bloom that plant themselves once you let them go to seed.
Full sun
Every 5–7 days
USDA 3–9
5–8 ft · 1.5–2.4 m
Overview
Hollyhocks are the cottage-garden classic, sending up flower spikes that can clear 8 feet (244 cm) and line a fence or back wall in summer color. They belong to the mallow family and have been a dooryard favorite for generations, prized for the way their saucer-shaped blooms climb a single tall stalk from June through August.
Despite their height, they are an easy plant to grow. Most are biennials, which means a plant spends its first year as a low rosette of leaves and saves its flowering for the second year. They make up for that slow start by self-seeding hard, so once you have a stand going it tends to keep itself going.
The one thing every hollyhock grower learns to manage is rust, a leaf fungus that follows the plant almost everywhere. Give the plants full sun, room for air to move, and water at the roots instead of over the top, and you'll keep the worst of it in check while the flowers do their thing.
Care
The short version: give hollyhocks full sun and rich, well-drained soil, keep them evenly moist by watering at the base, and space them out so air can move and rust stays down.
Light
Hollyhocks want full sun to flower their best and stand up straight without flopping. They'll take a little partial shade, but in too much shade the stalks stretch, lean, and bloom thinly.
Water
Give them average, even moisture rather than letting the soil swing from soaked to bone dry. Water at the base with a soaker hose or drip line to keep the leaves dry, which is one of the best ways to slow rust. They won't tolerate wet, soggy soil over winter.
Soil
Plant in average, rich, well-drained loam worked with some compost. They're easygoing about pH and grow well anywhere from 6.0 to 8.0, but sharp drainage matters far more than the exact reading.
Humidity
Ordinary outdoor humidity suits them fine, so there's no number to chase. What counts here is airflow, since still, damp air around crowded leaves is exactly what rust needs to take hold.
Feeding
A single feed in spring is plenty. Work in compost or a balanced general-purpose fertilizer as growth starts, and the plants carry themselves through the season from there.
Pruning
Cut the spent flower spikes to neaten the plant or to rein in self-seeding if it's spreading more than you'd like. Just as important, strip off and destroy any rust-spotted lower leaves and clear all the old debris in fall so the fungus can't overwinter.
Size & spacing
These are tall plants, running from 5 to 8 feet (152 to 244 cm) high but staying narrow at 12 to 24 inches (30 to 61 cm) across. Give each one that full spread of room so air moves freely between them and rust has a harder time spreading.
When to plant
Hollyhocks run on a two-year clock. Sow the seed in late summer or start it indoors in late winter, set young plants out after the last spring frost, and the flowers come in from June through August of the following year.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Late winter to early spring, about 8 to 10 weeks before the last frost.
- Plant: After the last spring frost once soil has warmed.
- Harvest: June through August.
Hardiness
USDA hardiness zones: 3–9
Temperature: down to -40°C
Troubleshooting
Almost every hollyhock problem shows up on the leaves, and rust is the one you'll meet first. Match what you see below, then act early, since most of these are easier to head off than to cure once they spread.
Orange spots up top, rusty pustules underneath
This is hollyhock rust, the one disease that follows this plant everywhere. The fungus shows as yellow-orange spots on the upper leaf with raised rusty bumps right beneath them, and badly hit leaves turn holey and shrivel. Pull the marked leaves the moment you see them, water at the base to keep the foliage dry, and rake up every scrap of debris in fall so the spores can't overwinter.
Fix:
- Remove and destroy symptomatic leaves early
- Clear all hollyhock debris in fall
- Water at the base to keep foliage dry
- Remove weedy mallows nearby
- Apply a labeled fungicide before symptoms appear if rust is recurrent
Leaves chewed down to a lacy skeleton
Two pests give this look. Japanese beetles feed in groups by day and leave the leaf veins behind like lace, while slugs work at night and give themselves away with slime trails. Pick the beetles off into soapy water in the early morning, and set out baits or traps where slugs are the problem.
Fix:
- Hand-pick beetles into soapy water in early morning
- Reduce nearby turf grub habitat
- Use slug baits or traps where slugs are present
Fewer blooms and pinholes in the buds
The culprit is the hollyhock weevil, a tiny black insect with tan legs and a long snout that you'll spot on the buds and open flowers. It bores into buds and seeds, which thins out the bloom. Shake the weevils onto a sheet and destroy them, and clear away old seed heads where the larvae grow up.
Fix:
- Hand-pick or shake weevils onto a sheet and destroy them
- Remove and destroy old seed heads where larvae develop
Tattered lower leaves with dark blotches
Leaf spot and anthracnose fungi settle into the lower foliage when plants stand crowded, stressed, or wet from overhead watering, though the flowers stay clean. The damage looks rough but rarely threatens the plant. Strip off the worst leaves, open up the spacing for airflow, and water at the base.
Fix:
- Remove affected leaves
- Improve air circulation
- Water at the base rather than overhead
Toxicity
Good news for households with pets: the ASPCA lists hollyhock as non-toxic to cats, dogs, and horses, and the flowers are safe enough that people eat them. The only thing to watch is the bristly leaves and fibers, which can leave a mild skin rash on sensitive people, so it's worth pulling on gloves before you handle or cut the plants.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
The ASPCA lists hollyhock as non-toxic to cats, so a curious nibble won't poison one. A cat that gorges on any plant might cough some back up, but there's nothing here to fear.
Dogs None
Dogs are in the clear too. Hollyhock is non-toxic to dogs, and the worst a leaf-chewing pup is likely to get is a brief, mild stomach upset from the roughage.
Horses None
Horses can graze near hollyhocks without worry, since the plant carries no toxic principles for them.
Rabbits Safe
Rabbits can eat the leaves and flowers safely, as these mallow-family plants hold nothing harmful to them.
Livestock Safe
Cattle, goats, and sheep face no toxic risk from hollyhock if they browse a plant in the pasture or garden edge.
Birds Safe
Backyard birds and poultry can peck at the foliage and seeds without harm.
People Safe
The plant is safe for people, and the flowers are even edible, often used as a garnish or steeped for tea. The one caveat is the bristly leaves and fibers, which can leave a mild skin rash on sensitive folks, so it's worth wearing gloves when you handle or cut the plants.
Contact with the bristly foliage and plant fibers can cause skin irritation (contact dermatitis) in sensitive people; wear gloves when handling.
Varieties
Most garden hollyhocks are the common Alcea rosea, but a few stand out for their color or their resistance to rust. These are the ones worth knowing by name.
Nigra
Its deep maroon flowers run so dark they read as nearly black against the green spike.
Russian hollyhock (Alcea rugosa)
A close relative with soft yellow flowers that shrugs off hollyhock rust far better than the common kind.
Figleaf hollyhock (Alcea ficifolia)
Named for its fig-shaped leaves, this species also stands up to rust better than Alcea rosea.
How to propagate
Hollyhocks are simple to grow from seed, and once a stand is established it largely sows itself.
SeedEasy
Sow in late summer (August to September) for bloom the following year, or start indoors in late winter for transplanting after frost. · Germinates in about 1 to 2 weeks; plants form a rosette the first year and bloom the second year.
Seed is the easy way to grow hollyhocks. Sow in late summer, around August to September, for flowers the next year, or start indoors in late winter and set the plants out after frost. Seedlings break ground in 1 to 2 weeks, then spend their first year as a low rosette and bloom in the second. Leave the seed heads in place and they reseed on their own, naturalizing into standing colonies.
Myths
Hollyhocks are poisonous and need to be kept away from dogs and cats.
The ASPCA lists hollyhock as non-toxic to dogs, cats, and horses, so a nibble in the garden is no cause for alarm. The flowers are safe enough that people eat them. The only real catch is the bristly leaves, which can leave a mild rash on sensitive skin, so wear gloves when you cut the plants.
Hollyhocks are reliable, long-lived perennials.
Most hollyhocks are biennials, growing a leafy rosette the first year and flowering the second before they fade. They look permanent only because they self-seed so freely that fresh plants keep filling the same spot year after year.