PlantingWindowThe American Planting Almanac

When to plant borage in Milwaukee, Wisconsin

April 26 – May 10

Direct-sow outdoors · typical Milwaukee year

Climate basis: NOAA station West Allis, WI (USC00479046), 6 mi (10 km) from downtown Milwaukee (ZCTA 53202 centroid), elevation 723 ft, on the 1991–2020 climate normals. Direct-sow borage from approximately the dates above, anchored to the median last spring 32°F freeze (April 26). One year in ten still freezes after May 12.

Last spring freezeApril 261-in-10 after May 12
First fall freezeOctober 221-in-10 before Oct 7
Frost-free season≈ 177 daysmedian at 32°F
Hard freeze, 28°Apr 14 – Nov 1kills even hardy greens
USDA zone6a-10 to -5°F winter low — not frost timing

The Milwaukee year

Start seeds indoorsMar 15 – Mar 29
Direct-sow outdoorsApr 26 – May 10
  • indoors under lights
  • in the garden
  • frost-free season
  • 1-in-10 years still freeze to May 12
Borage in Milwaukee · freeze context from West Allis, WI, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Mar 15 – Mar 29

Illinois Extension permits starting borage indoors but gives no lead time, so the offset comes from Virginia Cooperative Extension's herb publication — whose annual herb table lists borage — which sows small herb seed about six weeks before the last frost date. Anchored to the median last spring freeze (Apr 26). Virginia Cooperative Extension, Virginia Tech

Direct-sow outdoors

Apr 26 – May 10

Illinois Extension sows borage directly in the garden after frost is past, a point rule that opens a two-week sowing span at the last spring freeze. Anchored to the median last spring freeze (Apr 26). University of Illinois Extension · Virginia Cooperative Extension, Virginia Tech

Variety assumption: Virginia Cooperative Extension lists borage as a self-sowing annual; it resents root disturbance, so direct sowing is the usual method.

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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