In zone 6, plant basil outside around May 15, about two weeks after your last spring frost, once the soil is at least 60 °F. Start seeds indoors from March 20 to April 3. Basil is sensitive to cold, so don’t rush it.
Basil dates for your ZIP code
Planting times based on university extension guidance (UNH, Cornell, Purdue, Minnesota, Nebraska and UMass Extension). Frost dates from NOAA 1991–2020 U.S. Climate Normals, nearest weather station. Zones derived from the 2023 USDA Plant Hardiness Zone Map data (PRISM Climate Group, Oregon State University). This is not the official USDA Plant Hardiness Zone Map.
Basil timing in zone 6
| Task | When |
|---|---|
| Start indoors | March 20 – April 3 |
| Transplant outside | May 15 |
| First harvest | May 19 – June 12 |
| Sow again | Every 2 weeks for a steady supply |
| Pinch tips and flower buds | All season, as soon as buds form |
| Final harvest | Before nights drop toward 50 °F |
Most of zone 6 sees its last spring frost between April 25 and May 8 (typical May 1) and its first fall frost between October 7 and October 18 (typical October 13). Basil is damaged at temperatures around 50 °F, well above freezing, so it waits until nights are warm. The tool above uses the weather station closest to your ZIP code.
Why basil waits for warm weather
Basil is a tender annual herb that is sensitive to cold. Cold soil and air stunt its growth, and temperatures around 50 °F, well above freezing, can blacken its leaves. That is why it goes outside after the frost-free date, once the soil reaches at least 60 °F.
Best basil varieties for zone 6
Zone 6 summers are ideal for basil. Grow a few kinds:
- Genovese basil for pesto and Italian cooking.
- Thai basil, with a licorice-like aroma.
- Lemon basil, strongly lemon-scented.
- Purple basil: Dark Opal, Emerald Wine and Rubin.
How to plant basil
- Start seeds indoors in a warm spot: they need at least 70 °F and sprout in 5–7 days.
- Grow seedlings in full sun or under lights.
- Transplant after your frost-free date, once the soil is 60 °F or warmer.
- Pinch the stem tips once plants have a few sets of leaves, to make them bushy.
- Sow again every two weeks for a continuous supply.
Zone 6 basil tips
- Plant once the soil is 60 °F and the frost-free date has passed.
- Sow in batches every two weeks for a continuous supply.
- Remove flower buds as soon as you see them, so the plant keeps making leaves.
- Don’t refrigerate fresh basil. It turns the leaves dark. Keep stems in water on the counter, or dry the leaves.
Harvesting basil
Harvest lightly from young plants, then pick individual leaves and stem tips as the plants grow. Regular picking keeps basil bushy and productive. Remove flower buds as soon as they appear. Basil can be harvested about 60–70 days after sowing, and it dries easily for winter use. Avoid refrigerating fresh basil, which darkens the leaves.
Basil planting dates in nearby zones
See dates for every zone on the basil planting guide, or build a full schedule with the planting calendar.
Frequently asked questions
Is it too late to plant basil in zone 6 in June?
No. Basil planted in June grows quickly in summer heat and keeps producing until cool fall nights.
Why are my basil leaves turning black?
Usually cold. Basil is damaged around 50 °F. Protect it on cool nights or harvest before they arrive.
Can I plant basil before the last frost?
No. Basil is damaged by cold even above freezing. Plant it out after your frost-free date, once the soil is 60 °F.
Should I remove basil flowers?
Yes. Pinch off flower buds as soon as they form so the plant keeps producing leaves.
How do I store fresh basil?
Not in the refrigerator, which turns the leaves dark. Keep stems in water at room temperature for a few days, or dry the leaves.
Sources. Planting dates use the median frost dates of each USDA zone, calculated from NOAA climate data for every ZIP code in the zone.