Flowers

How to Grow Hollyhock: Planting, Spacing, Care & Bloom

Quick answer

Direct sow from spring until about 8 weeks before the first heavy fall frost (Cornell). Or fall-sow after a killing frost (UVM). Biennial to short-lived perennial; self-seeds (NC State).

Hollyhock at a glance

PlantDirect sow: last frost; Direct sow (until cutoff): 8 wk before last frost; Fall sow: last frost
SunFull sun to light shade; moist, well-drained, organic-rich soil (NC State).
SpacingNC State: space about 12 inches–3 feet; height 5–8 ft; width 1–2 ft.
Days to bloomBiennial; bloom year 2 typical (NC/Cornell)
-9-8-7-6-5-4-3-2-1LF+1+2+3
■ Start indoors   ■ Plant out   ■ Harvest
Weeks relative to last frost (LF). Colored weeks show when our ZIP planner schedules each step.
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Updated

Hollyhock (Alcea rosea) — biennial to short-lived perennial; often flowers in year 2 from seed.

Purple hollyhock flowers
Hollyhock (Alcea rosea). Photo: PJDespa, Wikimedia Commons, CC BY-SA 3.0 (resized).

Sourced from university extension guides. For dates where you live, use the ZIP planting planner.

Planting timing

Cornell: “Sow seeds outdoors anytime from spring until 2 months before the first heavy fall frost. Do not cover, as light aids germination.” Emergence about 10 to 14 days. (Cornell hollyhock) University of Vermont: among biennials good for fall direct sowing — “plant them after a killing frost so that they do not have a chance to germinate until … spring.” (UVM fall seeds) Planner: spring start at last frost 0; season continues until first frost −8; fall sow at first frost 0.

Depth and spacing

Cornell: do not cover seed (light aids germination). NC State: space about 12 inches–3 feet; height 5–8 ft; width 1–2 ft.

Sun, soil and water

Full sun to light shade; moist, well-drained, organic-rich soil (NC State). Leaves may wither in summer heat; rust and leaf spots are common in humid weather.

Care

May need staking in rich soils (Cornell). Biennial habit — flowers often in year 2; self-seeds so stands persist. For rust: water from below, space for air, remove infected leaves.

Bloom

NC State: long bloom about June–August. Cornell: mid-summer through early fall. Cut flowers possible; no single days-to-bloom integer is sourced.

Pests and diseases

NC State: rust, leaf spot, anthracnose; slugs, spider mites, Japanese beetles. Keep foliage dry and spaced. Japanese beetles: handpick/soapy water; neem; Bt galleriae as labeled (UMN). Slugs: handpick or iron phosphate bait (UC IPM).

Related: ZIP planner · organic pest control

Frequently asked questions

When do I sow hollyhock seed?

From spring (last frost 0) until about 8 weeks before first heavy fall frost (first frost −8) — Cornell. Or fall-sow after a killing frost (first frost 0) — UVM.

Is hollyhock a perennial?

Biennial to short-lived perennial; self-seeds (NC State/Cornell).

Do hollyhocks need staking?

Often yes in rich soils (Cornell).

Sources