When to plant basil

Basil (warm-season annual herb) is classed very tender in the cited extension guidance. The timing rules below are relative to your local freeze dates — enter a location to turn them into calendar dates.

The rules this site applies

Method	Frost-relative window	Rule & reconciliation
Start seeds indoors	5–4 weeks before the median last spring freeze	Iowa State: start seeds indoors 4 or 5 weeks before the last frost date.
Transplant outdoors	14–30 days after the median last spring freeze	UNH: set out 2 weeks after the last frost; Oklahoma State: plant one month after the last spring frost; Iowa State: after all danger of frost. The window spans the UNH and Oklahoma State recommendations.
Direct-sow outdoors	30–44 days after the median last spring freeze	Oklahoma State Table 1 times basil planting one month after the last spring frost; Iowa State adds direct sowing once nights stay above 50°F. Point rule given a 14-day span.

Variety assumption: Leaves are harvestable about 30–40 days after transplanting.

Crop rule sources (3)

Iowa State University Extension and Outreach: Growing Basil in the Home Garden (accessed 2026-07-24)
"Start seeds indoors 4 or 5 weeks before the last frost date." "Plant basil outdoors after all danger of frost is past."
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.
Oklahoma State University Extension: Culinary Herbs for Oklahoma Gardens: Culture, Use and Preservation (accessed 2026-07-24)
Table 1 planting times relative to last spring frost for common herbs.

Reviewed city pages for basil