When to Plant Hollyhock in Onslow, Iowa (52321)

Location

Onslow, Iowa

ZIP Code

52321

USDA Zone

Last Frost

Sunday, May 10, 2026

📅 Planting Calendar

Start Seeds Indoors Sunday, March 29, 2026

Transplant Outdoors Sunday, May 24, 2026

Pro Tip: Start Hollyhock seeds indoors 6 weeks before your last frost date, then transplant outdoors around Sunday, May 24, 2026.

🌿 Plant Details

Scientific Name Alcea rosea

Days to Maturity 365 days

Mature Height 48-96"

Spread 24"

☀️ Growing Requirements

☀️

Sun

Full Sun (6-8 hours)

💧

Water

Moderate (1 inch/week)

↔️

Spacing

18" apart

🌱

Planting Depth

0.25" deep

Seeds typically germinate in 10-14 days

Ready to Plant Hollyhock in Onslow?

Get your seeds now so they're ready by Sunday, March 29, 2026.

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Growing Hollyhock in Zone 5a

Hollyhock (Alcea rosea) is a popular garden vegetable. In Onslow, Iowa, which is in USDA Hardiness Zone 5a, you should start seeds indoors around Sunday, March 29, 2026.

Your average last frost date is Sunday, May 10, 2026. Plan to transplant your Hollyhock seedlings outdoors around Sunday, May 24, 2026, about 2 weeks after your last frost date.