Annual Flower

When to Plant Marigolds in New Hampshire

The ultimate companion plant. Marigolds repel pests, attract pollinators, and add cheerful color all season long.

The Short Answer

In New Hampshire, plant marigolds based on your regional frost dates. Northern New Hampshire has a last frost around May 20 - Jun 5, while Southern New Hampshire sees frost end around May 1 - May 20. Short growing season especially in north. Cold winters. Cool summers. Hardy varieties important.

New Hampshire Frost Dates

Your planting dates depend on which part of New Hampshire you're in. Here are the frost date ranges by region:

Region Zones Last Frost (Spring) First Frost (Fall)
Northern New Hampshire 3b, 4a, 4b May 20 - Jun 5 Sep 10 - Sep 25
Southern New Hampshire 5a, 5b, 6a May 1 - May 20 Sep 25 - Oct 10

Marigolds Planting Schedule for New Hampshire

Northern New Hampshire (Zones 3b, 4a, 4b)

Average last frost: May 20 - Jun 5 · Average first frost: Sep 10 - Sep 25

Start Seeds Indoors
6 wks before frost
Transplant Outside
1 wks after frost
Direct Sow
1 wks after frost

Southern New Hampshire (Zones 5a, 5b, 6a)

Average last frost: May 1 - May 20 · Average first frost: Sep 25 - Oct 10

Start Seeds Indoors
6 wks before frost
Transplant Outside
1 wks after frost
Direct Sow
1 wks after frost

Growing Marigolds in New Hampshire

Marigolds in New Hampshire's Climate

Marigolds are surprisingly effective in cold climates despite their frost sensitivity. Start indoors or buy transplants — they grow fast once summer warmth arrives. Plant among vegetables for pest deterrence. French marigolds suppress root-knot nematodes through root chemicals, though nematodes are less common in cold soils.

Soil Considerations for New Hampshire

Rocky, acidic New England soils. Glacial deposits. Granite bedrock. Raised beds essential in many areas. Make sure soil has warmed to at least 60°F before planting marigolds outside.

New Hampshire Climate & Growing Season

Short growing season especially in north. Cold winters. Cool summers. Hardy varieties important. Marigolds cannot tolerate any frost, so wait until all frost danger has passed before transplanting outside. Watch local forecasts carefully in spring.

Growing season length varies across New Hampshire: Northern New Hampshire (3b, 4a, 4b) has a last frost around May 20 - Jun 5, while Southern New Hampshire (5a, 5b, 6a) sees frost end around May 1 - May 20. This difference matters for marigolds — transplant timing shifts by several weeks across the state.

Growing Tips

French marigolds are best for pest control in vegetable gardens. Deadhead spent flowers to keep them blooming until frost.

Companion Planting

Plant marigolds alongside these companions for better growth:

Tomatoes Peppers Squash Beans

The Bottom Line

Marigolds can be grown successfully across New Hampshire, but your exact planting dates depend on which region you're in. Northern New Hampshire gardeners should plan around a May 20 - Jun 5 last frost, while those in Southern New Hampshire can typically plant earlier. For exact dates based on your zip code, use our free planting date finder.

Related Guides

Marigolds Growing Guide National planting guide with all states New Hampshire Planting Calendar All plants for New Hampshire Marigolds in Alabama Alabama planting dates Marigolds in Alaska Alaska planting dates Marigolds in Arizona Arizona planting dates Marigolds in Arkansas Arkansas planting dates
Note: All dates are based on NOAA 30-year Climate Normals and represent historical averages, not predictions for any specific year. Always check your local weather forecast before planting frost-sensitive crops. Learn about our data sources.

Last reviewed: March 29, 2026

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