PlantingWindowThe American Planting Almanac

When to plant turnips in Des Moines, Iowa

March 21 – April 4

Direct-sow 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. Direct-sow turnips 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

Direct-sow 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
Turnips in Des Moines · freeze context from Des Moines INTL AP, IA, 1991–2020 normals.

Every method, with its sources

Direct-sow outdoors

Mar 21 – Apr 4

Purdue: hardy — 4–6 weeks before the last frost; Penn State's earliest sowing Apr 3 (−28 days) is the later start and is used. Anchored to the median last spring freeze (Apr 18). Penn State Extension (York County Master Gardeners) · Purdue University Extension

Fall planting

Aug 25 – Sep 22

Purdue Table 2: plant fall turnips 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 variety (about 45–60 days; Penn State lists 55).

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 (2)

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