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
Few plants set a scene like the hollyhock, the cottage-garden classic whose flower spikes rise past 8 feet (244 cm) to soften a fence, frame a doorway, or draw the eye up a back wall through the summer. A member of the mallow family, it has anchored dooryard gardens for generations, and those saucer-shaped blooms marching up a single tall stalk from June through August give a border instant vertical romance.
For all its stature, it is an easy plant to grow and an easy one to weave into a garden routine. Most are biennials, spending the first year as a quiet rosette and saving their flowering for the second year, then self-seeding freely so a planting renews itself with little help. That habit makes hollyhock a natural fit for a relaxed, informal corner rather than a manicured bed.
The one thing every hollyhock grower learns to manage is rust, a leaf fungus that shadows the plant almost everywhere. Site it in full sun with room for air to move and water at the roots rather than over the top, and the display stays handsome along a path or boundary while the flowers carry the season.
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
Give hollyhocks full sun and they flower their best while standing tall and upright, the look you want at the back of a border. They accept a little partial shade, but in too much shade the stalks stretch, lean, and bloom thinly, losing the clean vertical line.
Water
Keep the soil at average, even moisture rather than letting it swing from soaked to bone dry. Water at the base with a soaker hose or drip line to keep the leaves dry, one of the surest ways to slow rust and keep the planting looking fresh. They will not tolerate wet, soggy soil over winter.
Soil
Plant in average, rich, well-drained loam worked with a little compost. They are easygoing about pH and settle in anywhere from 6.0 to 8.0, so sharp drainage matters far more than the exact reading.
Humidity
Ordinary outdoor humidity suits them fine, so there is no figure to chase. What counts is airflow, since still, damp air around crowded leaves is exactly what rust needs to take hold and dull a display.
Feeding
A single feed in spring is all it asks. Work in compost or a balanced general-purpose fertilizer as growth starts, and the plants carry the border through the rest of the season on their own.
Pruning
Cut the spent flower spikes to keep the planting neat or to rein in self-seeding if it wanders further than you would like. Just as important, strip off and destroy any rust-spotted lower leaves and clear all the old debris in fall so the fungus cannot overwinter.
Size & spacing
These are tall plants, rising 5 to 8 feet (152 to 244 cm) high while staying narrow at 12 to 24 inches (30 to 61 cm) across, which makes them ideal for a slim strip along a wall. 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 keep a two-year rhythm that rewards a little planning. 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 arrive to fill the garden 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 concern turns up on the leaves, and rust is the one you will meet first. Match what you see below, then act early, since most of these are far easier to head off than to undo once they take over a planting.
Orange spots above, rusty pustules below
The usual visitor is hollyhock rust, the one disease that trails this plant through almost every garden it graces. Yellow-orange spots sit on the upper leaf with raised rusty bumps directly beneath, and the worst leaves turn holey and shrivel, which is what spoils the tidy look along a fence line. Lift out the marked leaves early, water at the base so the foliage stays dry, and sweep up all the debris in fall so nothing carries over to the next season.
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
Foliage chewed to a lacy pattern
Two pests leave the foliage looking like lace at the height of summer. Japanese beetles gather in the daylight and strip the leaf down to its veins, while slugs slip in after dark and leave a slime trail as their calling card. Drop the beetles into soapy water in the cool of early morning, and put out baits or traps wherever the slugs are settling in.
Fix:
- Hand-pick beetles into soapy water in early morning
- Reduce nearby turf grub habitat
- Use slug baits or traps where slugs are present
A thinner show and pinholes in the buds
When the display thins out, the hollyhock weevil is usually the reason, a tiny black insect with tan legs and a long snout that settles onto the buds and open flowers. It bores into buds and seeds, which quietly costs you a fuller show along the border. Tap the weevils onto a sheet and dispose of them, then clear away the old seed heads where the next generation grows up.
Fix:
- Hand-pick or shake weevils onto a sheet and destroy them
- Remove and destroy old seed heads where larvae develop
Untidy lower leaves with dark blotches
Leaf spot and anthracnose fungi take up residence in the lower foliage when plants stand crowded, stressed, or wet from overhead watering, though the flowers themselves stay untouched. The look turns scruffy at the base, yet the plant is rarely in any danger. Lift away the worst leaves, give the planting more breathing room, and water at the base to restore a cleaner line.
Fix:
- Remove affected leaves
- Improve air circulation
- Water at the base rather than overhead
Toxicity
Reassuring news for a home 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 one thing to keep in mind is the bristly leaves and fibers, which can leave a mild skin rash on sensitive people, so it is worth keeping gloves on hand before you handle or cut the plants.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
A cat wandering the border is in good company, since the ASPCA lists hollyhock as non-toxic to cats, and a curious taste will not poison one. A cat that overindulges on any greenery might bring a little back up, but there is nothing here to trouble the household.
Dogs None
The family dog can share the garden without concern. Hollyhock is non-toxic to dogs, and a leaf-chewing companion is unlikely to feel anything worse than a brief, mild stomach upset from the roughage.
Horses None
Horses may graze near a planting of hollyhocks with ease, as the plant carries no toxic principles for them.
Rabbits Safe
Rabbits can browse the leaves and flowers safely, since these mallow-family plants hold nothing harmful to them.
Livestock Safe
Cattle, goats, and sheep face no toxic risk from hollyhock should they browse a plant along the pasture or a garden edge.
Birds Safe
Backyard birds and poultry can visit the foliage and seeds without any harm, a quiet bonus for a garden that welcomes wildlife.
People Safe
The plant is safe for people, and the flowers are edible, elegant as a garnish on the table or steeped into a tea. The single caveat is the bristly leaves and fibers, which can leave a mild skin rash on sensitive skin, so keep a pair of gloves handy 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 apart for their color or their resistance to rust, and those are the ones that shape the character of a planting. These are worth knowing by name.
Nigra
Its deep maroon flowers run so dark they read as nearly black against the green spike, a dramatic note for a moody planting scheme.
Russian hollyhock (Alcea rugosa)
A close relative with soft yellow flowers, it shrugs off hollyhock rust far better than the common kind and keeps a border looking fresher.
Figleaf hollyhock (Alcea ficifolia)
Named for its fig-shaped leaves, this species also stands up to rust better than Alcea rosea, an easy pick for a low-maintenance display.
How to propagate
Hollyhocks are simple to raise from seed, and once a planting is established it largely sows itself into the garden.
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 graceful way to fill a border with hollyhocks. Sow in late summer, around August to September, for flowers the following year, or start indoors in late winter and set the plants out after frost. Seedlings appear in 1 to 2 weeks, hold as a low rosette through the first year, and flower in the second. Leave the seed heads in place and the planting reseeds itself, settling into standing colonies that return to the same spot on their own.
Myths
Hollyhocks are poisonous and belong nowhere near dogs and cats.
There is no need to keep this cottage favorite out of a home with animals. The ASPCA lists hollyhock as non-toxic to dogs, cats, and horses, so a nibble in the border 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, spending the first year as a leafy rosette and flowering in the second before they fade. They only seem to hold a spot forever because they self-seed so freely that fresh plants keep filling the same corner of the garden year after year.