New Hampshire vegetable planting calendar 2027: frost dates and when to plant

In New Hampshire, the average last spring frost is May 8 in Concord and April 21 in Manchester (NOAA 1991-2020 normals). Below are planting dates for Concord and Manchester for 27 common vegetables and herbs, worked out the way the Rowtime app does it: NOAA's average frost dates for the nearest weather station, with the planting rules of state extension guides. Dates are for the 2027 season.

Rowtime: Garden Planner works these dates out for your own ZIP code in New Hampshire, shows where each one comes from, and recalculates when a planting slips. Get Rowtime on the App Store.

Dates are estimates. Check your local extension office before you plant, and use your own frost records if you have them. Dates shift by a week or more within a state, so pick the city closest to your conditions.

Concord Manchester

Concord

When to plant tomatoes in Concord?

In Concord, New Hampshire, the average last spring frost is May 8 and the average first fall frost is October 3 (NOAA 1991-2020 normals, CONCORD MUNI AP station, 6.6 km from ZIP 03301). For tomatoes, start seeds indoors April 12 to June 18 and plant out seedlings May 22 to July 5, following University of Maryland Extension (Home & Garden Information Center) and Purdue University Extension. Dates are for the 2027 season; sources last checked October 24, 2026.

Concord Manchester

Manchester

When to plant tomatoes in Manchester?

In Manchester, New Hampshire, the average last spring frost is April 21 and the average first fall frost is October 19 (NOAA 1991-2020 normals, MANCHESTER AP station, 6.6 km from ZIP 03101). For tomatoes, start seeds indoors March 26 to June 1 and plant out seedlings May 6 to July 21, following University of Maryland Extension (Home & Garden Information Center) and Purdue University Extension. Dates are for the 2027 season; sources last checked October 24, 2026.

Concord Manchester

Sources

Planting rules, in the order Rowtime tries them here:

• Purdue University Extension, Indiana Vegetable Planting Calendar (HO-186-W). Checked October 20, 2026.
• University of Maryland Extension (Home & Garden Information Center), Vegetable Planting Calendar for Central Maryland. Checked October 24, 2026.
• NC State Extension, Central North Carolina Planting Calendar for Annual Vegetables, Fruits, and Herbs (AG-756-01). Checked October 21, 2026.

Frost dates, locations and zones:

• NOAA National Centers for Environmental Information, U.S. Climate Normals 1991-2020 annual/seasonal (freeze probabilities).
• U.S. Census Bureau, 2025 Gazetteer Files: ZIP Code Tabulation Areas.
• PRISM Group, Oregon State University / USDA ARS, 2023 USDA Plant Hardiness Zone Map ZIP code listings. PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed 20 Oct 2026.

How the dates are worked out: a guide's rule such as "two weeks after the last frost" is applied to the station's NOAA date. Purdue's dates are 10% dates, so they are counted from the station's 10% date. When a guide gives no last date, the window closes early enough for the crop's longest days to harvest before the first fall frost. When a guide gives no first date for a fall planting, no fall window is shown. "Season too short" means the guide's window would close before it opens at this station's frost dates.

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