Most hollyhocks are biennials: leaves the first year, flowers the second (Illinois, SDSU). For flowers next summer, sow seed in late summer, at least 2 months before your first killing frost (UMaine), or sow in mid to late spring indoors or in the ground for flowers the following year (RHS). Plant potted hollyhocks in spring or fall (RHS), about 12 to 24 inches apart (SDSU, RHS), in full sun and well-drained soil, sheltered from wind (Illinois, RHS). Watch for hollyhock rust (Illinois, Wisconsin). The ASPCA lists hollyhock as non-toxic to dogs, cats and horses.
Hollyhock (Alcea rosea) is an old-fashioned cottage-garden flower in the mallow family, the same family as okra, cotton and hibiscus (Illinois). It is native to Asia (Illinois); NC State says probably Turkey and western Asia. Plants usually reach 3 to 6 feet, some nearly 9 (Illinois), and SDSU sees 6 to 8 feet. Flowers open from the bottom of the spike up, each lasting 3 to 4 days, for about four weeks of bloom (Illinois); NC State gives a June to August bloom. Colors run from white, yellow and pink to red and near-black (Illinois, SDSU). Some newer types behave as short-lived perennials (SDSU, UMaine).
When to plant hollyhocks
| Timing | What the sources say |
|---|---|
| Late summer to early fall (seed) | Old-fashioned hollyhocks are biennials. For flowers next year, UMaine says to sow at least 2 months before the first killing frost so plants can establish |
| Mid to late spring (seed) | RHS sows indoors in April or May at 61 to 70°F (16 to 21°C), or directly where plants will grow in May or June. SDSU sows saved seed in early spring. Old-fashioned types make leaves the first year and flower the next (Illinois, SDSU) |
| Spring or fall (potted plants) | RHS plants pot-grown hollyhocks in spring or autumn, though it says they can go in at any time |
| Winter (outdoor sowing) | UMaine suggests winter-sowing in a milk jug left outside, for plants ready to set out early |
| Self-sown seedlings | Hollyhocks reseed readily (Illinois, NC State). RHS says they are not long-lived, so let seedlings grow on to replace older plants |
Our planting calendar shows your average first fall frost. Count back about 2 months for a late-summer sowing (UMaine). For seed, UMaine soaks it in warm water for 12 hours and lays it on the soil surface so it gets light; RHS says it germinates easily at 61 to 70°F. Once you have a patch, leave a few spikes to drop seed and you will have plants of both ages, so some flower every year (SDSU, Illinois).
How to plant hollyhocks
| Hollyhock | |
|---|---|
| Light | Full sun (Illinois, SDSU, RHS); NC State says full sun to light shade |
| Soil | Well drained (Illinois); fertile for the tallest spikes, though they grow in any garden soil (RHS); NC State lists moist, well-drained loams rich in organic matter |
| Spacing | 12 to 18 in for potted plants, leaving 3 to 4 ft for the patch to fill in by self-seeding (SDSU); RHS spaces 24 in |
| Shelter | Protect from wind or stake (Illinois, RHS). A fence or wall makes a classic backdrop (Illinois) |
| Feeding | Slow-release fertilizer at planting; little needed once established (SDSU). RHS adds compost instead of feeding |
Watering, staking and deadheading
- Water new plantings well while they establish (SDSU, RHS).
- Stake in windy spots with a bamboo cane (RHS). Illinois pinches main stems early for shorter, bushier plants that need less staking.
- Deadhead or let them seed. SDSU says removing flowers after bloom helps perennial types come back; leave some spikes if you want self-sown seedlings (SDSU, Illinois). Save seed once pods are brown and dry (SDSU, RHS).
- Cut spikes down after flowering (RHS).
Hollyhocks in containers
RHS says small plug plants usually need potting up and growing on indoors until they are large enough to plant outside. Our sources don't cover growing hollyhocks to flower in pots; given plants of 6 feet or more (SDSU), we would keep them in the ground (GardenPal reasoning).
Fall and winter
- Clean up for rust. The rust fungus overwinters in leaf and stem debris, so remove all hollyhock debris in fall (Wisconsin, Illinois, SDSU).
- Hardiness: RHS calls them fully hardy and removes dead leaves in winter; NC State lists zones 5 to 9.
- Overwinter fall sowings in a cold frame (RHS) or a milk jug outdoors (UMaine).
Pests and problems
Hollyhock rust is the most common problem: orange or yellow spots on the upper sides of lower leaves, then brown to dark-red bumps underneath (Illinois, Wisconsin). It can stunt plants and cause early leaf drop, and in rare cases it kills the plant (Wisconsin). Remove infected leaves early, pull out common mallow weeds that carry rust, don't crowd plants, water at the soil rather than with a sprinkler, mulch in spring, and don't save seed from infected plants (Illinois, Wisconsin). Wisconsin says resistant varieties don't resist every rust strain, and SDSU calls it hard to control, so SDSU suggests removing infected plants and starting over with new plants in a new spot; RHS discards badly affected plants. A preventive fungicide labeled for hollyhocks can be applied before infection or as soon as it is spotted; it stops spread but won't cure infected leaves (Illinois). Hollyhock weevils feed on buds and tender growth, and their larvae eat the developing seeds; remove infested pods (Illinois). Illinois and NC State also list Japanese beetles; RHS lists slugs, caterpillars and occasional flea beetles on young plants.
Hollyhocks around the vegetable garden
Hollyhocks are mallows, like okra (Illinois), and Wisconsin says rust also infects other mallow-family plants such as rose mallow, so in our view it makes sense not to plant them right beside okra (GardenPal reasoning). Their height suits the back of a border or a fence line (Illinois), and NC State says they attract bees, butterflies and hummingbirds. For other tall cottage-garden flowers, see when to plant delphiniums, when to plant foxgloves, when to plant zinnias and when to plant okra.
Frequently asked questions
When should I plant hollyhock seeds?
In late summer, at least 2 months before the first killing frost, for flowers next year (UMaine), or in mid to late spring indoors or in the ground (RHS).
Do hollyhocks bloom the first year?
Most don't. Old-fashioned hollyhocks are biennials that flower in their second year (Illinois, SDSU).
How far apart should I plant hollyhocks?
About 12 to 18 inches (SDSU) or 24 inches (RHS).
Do hollyhocks come back every year?
The plants often die after flowering, but they reseed readily, so a patch keeps going if you let some seed drop (SDSU, Illinois).
How do I stop hollyhock rust?
Remove infected leaves early, clear debris in fall, pull common mallow weeds, space plants and keep leaves dry (Illinois, Wisconsin).
Are hollyhocks poisonous to dogs and cats?
No. The ASPCA lists hollyhock as non-toxic to dogs, cats and horses.
Enter your frost dates to time a late-summer hollyhock sowing or a spring planting.
Open itSources
- Virginia Cooperative Extension, "Companion Planting in Gardening" (SPES-620P)
- University of Maryland Extension, "Vegetable Succession and Companion Planting"
- Oregon State University Extension, "Companion Planting"
- Penn State Extension, "Herbs Make Good Plant Partners and Companions"
- University of Minnesota Extension, "Planting the vegetable garden"
- USDA Plant Hardiness Zone Map
- NOAA NCEI U.S. Climate Normals (frost/freeze data)
- University of Illinois Extension (Ken Johnson), "How to grow and care for hollyhocks"
- University of Wisconsin-Madison Extension, "Hollyhock rust"
- South Dakota State University Extension, "Growing hollyhocks"
- University of Maine Cooperative Extension, "What are your recommendations for planting hollyhock seeds in the fall?"
- NC State Extension Gardener Plant Toolbox, "Alcea rosea"
- Royal Horticultural Society, "How to grow hollyhocks"
- ASPCA Animal Poison Control, "Hollyhock"
Pairings are summarized in our own words from extension-service guidance. Research support for many companion effects is limited, so treat them as good habits, not guarantees.