When to plant broccoli in Des Moines, Iowa

March 21 – April 4

Transplant outdoors · typical Des Moines year

Climate basis: NOAA station Des Moines INTL AP, IA (USW00014933), 4 mi (6 km) from downtown Des Moines (ZCTA 50309 centroid), elevation 957 ft, on the 1991–2020 climate normals. Transplant broccoli outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (April 18). One year in ten still freezes after May 2.

Last spring freezeApril 181-in-10 after May 2

First fall freezeOctober 201-in-10 before Oct 4

Frost-free season≈ 184 daysmedian at 32°F

Hard freeze, 28°Apr 8 – Oct 30kills even hardy greens

USDA zone5b-15 to -10°F winter low — not frost timing

The Des Moines year

Start seeds indoorsFeb 7 – Feb 21

Transplant outdoorsMar 21 – Apr 4

Fall plantingAug 25 – Sep 22

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to May 2

Broccoli in Des Moines · freeze context from Des Moines INTL AP, IA, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Feb 7 – Feb 21

Sow 4–6 weeks before the set-out window opens (UNH 4–6 weeks; Missouri G6570 6–8 weeks). Anchored to the median last spring freeze (Apr 18). University of New Hampshire Extension · University of Missouri Extension

Transplant outdoors

Mar 21 – Apr 4

UNH: set out 2–4 weeks before the last frost; Purdue's hardy class allows 4–6 weeks before. The later UNH range is used. Anchored to the median last spring freeze (Apr 18). University of New Hampshire Extension · Purdue University Extension

Fall planting

Aug 25 – Sep 22

Purdue Table 2: plant fall broccoli at least 4–8 weeks before the first fall frost. Anchored to the median first fall freeze (Oct 20). Purdue University Extension

Variety assumption: Assumes an average heading variety (about 60–70 days from transplant).

These windows describe typical years (1991–2020 climate normals), not this year's forecast. Freezes happen outside them — especially in frost pockets, valleys, and urban edges. Watch the forecast before committing tender plants.

This week, not a typical year:

Crop rule sources (3)

University of New Hampshire Extension: Growing Vegetables: When to Plant Your Vegetable Garden [fact sheet] (accessed 2026-07-24)
Per-crop 'time from seed to transplant' and 'safe to set out in garden' relative to last frost.
University of Missouri Extension: Starting Plants Indoors from Seeds (G6570) (accessed 2026-07-24)
Weeks needed to grow vegetable transplants indoors (Table 2).
Purdue University Extension: Indiana Vegetable Planting Calendar (HO-186-W) (accessed 2026-07-24)
Hardiness classes: hardy = plant 4-6 wk before last spring frost; semi-hardy = 2-4 wk before; tender = after average last frost; very tender = at least 2 wk after. Table 2: fall planting at least 4-8 wk before first fall frost.

Keep exploring

This crop, other cities

Related crops in Des Moines

Local overview