When to plant basil in Delaware
Delaware’s average last spring frost is April 14, and the first fall frost typically arrives around October 22 — about 191 frost-free days (USDA zones 7a, 7b). Basil needs 30–60 days to mature, which fits comfortably within Delaware's growing season.
When to plant basil in Delaware: the short answer
For a spring planting, plant out Apr 21 – May 8, with seeds started indoors Mar 3 – Mar 17. Wait until the soil is at least 65°F and frost is over.
Succession sow again in Delaware: May 19 · Jun 9 · Jun 30 · Jul 21 · Aug 11 · Sep 1
Windows are ~1–2 week bands around each date. Frost dates are a statewide average from NOAA/NCEI normals; your town may differ by two weeks or more. Calendar year 2026.
How to grow basil in Delaware, step by step
- Start seeds indoors (Mar 3 – Mar 17). Sow seeds ⅛ inch deep in seed-starting mix under bright light. They take 5-10 days to sprout, fastest in soil around 80°F. Harden seedlings off for a week before they go outside.
- Prepare the bed. It needs at least six to eight hours of direct sun a day and loose soil at least 10 inches deep, with a pH between 6.0 and 7.0. Dig in compost before planting.
- Plant out (Apr 21 – May 8). Space plants about 10 inches apart in rows 12 inches apart. It is killed by frost, so nothing goes outside until the danger has passed.
- Water and feed. Give it steady, even moisture, about an inch of water a week from rain or the hose.
- Watch for pests and problems. Pests: aphids, Japanese beetle, slugs. Diseases and disorders: basil downy mildew, fusarium wilt, damping off.
- Harvest (from about May 28 – Jun 27). Basil takes 30-60 days to reach harvest. Cold soil stalls it - wait for warm nights. Pinch above a leaf pair every couple of weeks and remove flower buds to keep leaves coming. Downy mildew-resistant varieties are worth seeking out.
Figures come from our crop data; dates use Delaware’s average frost dates. More in the full basil growing guide.
When to plant basil in nearby states
| State | Last frost | Plant out |
|---|---|---|
| Delaware (this page) | April 14 | Apr 21 – May 8 |
| New Jersey | April 20 | Apr 27 – May 14 |
| Pennsylvania | May 1 | May 8 – May 25 |
| Maryland | April 14 | Apr 21 – May 8 |
| District of Columbia | April 10 | Apr 17 – May 4 |
| Virginia | April 15 | Apr 22 – May 9 |
| West Virginia | May 5 | May 12 – May 29 |
Questions gardeners in Delaware ask
When is the best time to plant basil in Delaware?
Plant basil transplants outdoors in Delaware between April 21 and May 8. That timing is set by Delaware's average last spring frost of April 14.
When should I start basil seeds indoors in Delaware?
Start seeds indoors between March 3 and March 17, about 5 weeks before the last frost, so the seedlings are ready to plant out from April 21.
What is the latest I can plant basil in Delaware?
About September 22. Basil needs at least 30 days to mature, and frost around October 22 ends the season, so later plantings risk being cut short.
When will basil planted in Delaware be ready to harvest?
Planted on time, basil is usually ready from about May 28 to June 27, 30-60 days after planting.
When is the last frost in Delaware?
On average around April 14, with the first fall frost around October 22 - about 191 frost-free days. Your town may differ by two weeks or more.