Flowers & bulbs

How to Grow Nasturtium: Planting, Care & Edible Flowers

Quick answer

Direct sow once all danger of frost has passed (Wisconsin), or start indoors in peat pots 4 to 6 weeks before last frost. Sow ½ inch deep (needs darkness); space 10 to 12 inches. Do not fertilize except on extremely poor soil — excess nitrogen means leaves and fewer flowers (Wisconsin). Edible flowers and leaves are peppery.

Nasturtium at a glance

PlantStart indoors: 6–4 wk before last frost; Direct sow: last frost
WaterWisconsin: dry soils OK; drought tolerant but water regularly for strong bloom.
SpacingWisconsin: sow ½ inch deep (needs darkness); 10 to 12 inches apart.
Days to bloomBloom season July–Oct. (Purdue HO-80)
-7-6-5-4-3-2-1LF+1+2+3
■ Start indoors   ■ Plant out   ■ Harvest
Weeks relative to last frost (LF). Colored weeks show when our ZIP planner schedules each step.
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Updated

Orange nasturtium flower
Nasturtium (Tropaeolum majus). Photo: George Chernilevsky, Wikimedia Commons, Public domain (resized).

Sourced from university extension guides. For dates where you live, use the ZIP planting planner.

Planting timing

Wisconsin: “Seed can be sown directly in the garden … once all danger of frost has passed or started indoors in peat pots 4 to 6 weeks before the date of the last expected spring frost.” (Wisconsin nasturtium) Planner: Direct sow last frost 0; Start indoors last frost −6 to −4.

Depth and spacing

Wisconsin: sow ½ inch deep (needs darkness); 10 to 12 inches apart. Soak seed overnight optional. Germination about 7–10 days.

Sun, soil and water

Wisconsin: dry soils OK; drought tolerant but water regularly for strong bloom. Do not fertilize except on extremely poor soil (excess N → leaves, fewer flowers).

Care, bloom and harvest

Deadhead to prolong bloom; blooms until frost (Wisconsin). Edible flowers and leaves, peppery (Wisconsin). Purdue HO-80 bloom window about July–October for planning.

Pests and diseases

Wisconsin lists imported cabbageworm and aphids; NC State also lists mealybugs and whiteflies. Aphids: soap or oil (UC IPM aphids). Cabbageworm: handpick; row cover if needed. Use any product as the label directs.

Related: ZIP planner · organic pest control · calendula

Frequently asked questions

When do I plant nasturtiums?

Direct sow after frost, or start indoors 4–6 weeks before last frost (Wisconsin).

Should I fertilize?

No, except on extremely poor soil (Wisconsin).

Are the flowers edible?

Yes — flowers and leaves are edible and peppery (Wisconsin).

Sources