When to Plant Broccoli in Iowa
Start Seeds Indoors
Saturday, March 14, 2026
Transplant outdoors: Saturday, April 25, 2026
State
Iowa
USDA Zones
4b, 5a, 5b, 6a
Avg Last Frost
Saturday, April 25, 2026
Cities Covered
934
Iowa Planting Schedule by Zone
Iowa spans 4 zones — find yours below for the most accurate dates.
| Zone | Last Frost | Start Indoors | Transplant |
|---|---|---|---|
| 4b | Tuesday, May 5, 2026 | Tuesday, March 24, 2026 | Tuesday, May 5, 2026 |
| 5a | Sunday, May 10, 2026 | Sunday, March 29, 2026 | Sunday, May 10, 2026 |
| 5b | Saturday, April 25, 2026 | Saturday, March 14, 2026 | Saturday, April 25, 2026 |
| 6a | Monday, April 20, 2026 | Monday, March 9, 2026 | Monday, April 20, 2026 |
Dates based on average last frost. Check your local forecast before planting.
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Growing Broccoli in Iowa: Complete Guide
Broccoli (Brassica oleracea var. italica) is a warm-season crop that needs a head start indoors before Iowa's last frost. Most Iowa gardeners begin seeds indoors around Saturday, March 14, 2026 and move transplants outside around Saturday, April 25, 2026, after the risk of frost has passed.
Because Iowa stretches across 4 USDA hardiness zones (4b, 5a, 5b, 6a), planting windows can shift by as much as two to four weeks from one end of the state to the other. Gardeners in the warmer southern zones can start earlier, while those in cooler northern zones should wait until the zone table above shows their last frost has passed.
With 60 days to maturity, Broccoli needs the indoor head start that Iowa's growing season requires. Starting indoors ensures you have strong transplants ready the moment outdoor conditions are right.
Broccoli requires full sun (6 hours) and regular (1-1.5 inches/week) moisture. Most of Iowa receives adequate sunlight during the growing season, though gardeners in humid eastern regions should watch for fungal issues and ensure good air circulation.
For the most precise planting dates tailored to your exact location, enter your ZIP code on our planting calendar or use the zone table above to find the schedule for your area of Iowa.
Growing Broccoli in Iowa: Local Tips
Climate-specific advice for Iowa gardeners.
Aim for heads before June heat
Start transplants 6 weeks before last frost and plant out in early April; Midwestern springs warm quickly — every week late you risk the heat that triggers bolting.
Fall crop is very productive
A mid-July transplant produces excellent heads in September–October in Ohio, Indiana, and Illinois; cool fall temps slow development and allow tight, high-quality head formation.
Frequently Asked Questions
When should I plant Broccoli in Iowa?
In Iowa, start Broccoli seeds indoors around Saturday, March 14, 2026 and transplant outdoors around Saturday, April 25, 2026 after your last frost. Iowa spans zones 4b–6a, so dates shift by 1–4 weeks depending on where you live.
What is the last frost date in Iowa?
Iowa spans 4 USDA zones (4b, 5a, 5b, 6a), so last frost dates vary by region. Riceville, Toeterville, Arlington (4b) sees frost until around Tuesday, May 5, 2026, while Council Bluffs, Carter Lake, Glenwood (6a) is frost-free much earlier.
How long does Broccoli take to grow in Iowa?
Broccoli takes about 60 days from transplant (or direct sow) to harvest. Starting seeds indoors in Iowa gives you a head start so plants are ready to go out after the last frost.
What USDA zones does Iowa cover for Broccoli?
Iowa includes zones 4b, 5a, 5b, 6a. Broccoli grows well across all of these zones with adjusted timing — use the zone table above to find the right dates for your part of the state.
Find Precise Dates for Your City
Select a city for exact planting dates based on local frost records.