When to plant borage in Tulsa, Oklahoma

March 31 – April 14

Direct-sow outdoors · typical Tulsa year

Climate basis: NOAA station Tulsa INTL AP, OK (USW00013968), 7 mi (11 km) from downtown Tulsa (ZCTA 74103 centroid), elevation 650 ft, on the 1991–2020 climate normals. Direct-sow borage from approximately the dates above, anchored to the median last spring 32°F freeze (March 31). One year in ten still freezes after April 15.

Last spring freezeMarch 311-in-10 after Apr 15

First fall freezeNovember 41-in-10 before Oct 20

Frost-free season≈ 220 daysmedian at 32°F

Hard freeze, 28°Mar 17 – Nov 13kills even hardy greens

USDA zone7b5 to 10°F winter low — not frost timing

The Tulsa year

Start seeds indoorsFeb 17 – Mar 3

Direct-sow outdoorsMar 31 – Apr 14

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to Apr 15

Borage in Tulsa · freeze context from Tulsa INTL AP, OK, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Feb 17 – Mar 3

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 (Mar 31). Virginia Cooperative Extension, Virginia Tech

Direct-sow outdoors

Mar 31 – Apr 14

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 (Mar 31). 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)

University of Illinois Extension: Borage | Herbs (accessed 2026-07-25)
"Borage is easily grown from seed started indoors or directly sown in the garden after frost is past."
Virginia Cooperative Extension, Virginia Tech: Herb Culture and Use (Publication 426-420) (accessed 2026-07-25)
"In addition, many culinary herbs, such as tarragon, can only be propagated asexually; seed-grown plants lack the oils that give them flavor."

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