How to Grow Nasturtiums From Seed

Nasturtiums are frost-tender, so sow them outdoors after the last spring frost once the soil has reached about 55 to 65F. They resent transplanting, so direct sowing where they will grow is easiest. In mild-winter areas like coastal California and the Gulf Coast you can also sow in fall for cool-season bloom, since nasturtiums actually flower best in the milder ends of the season and slow down in extreme summer heat.

Nasturtium seeds are large and easy to handle. Soak them in warm water for 12 to 24 hours first to soften the thick coat and speed things up, then sow about a half to one inch deep, which also gives them the darkness they need to germinate. Space mounding types about 6 inches apart and climbing types around 12 inches. They sprout in 7 to 14 days in lean, well-drained soil.

The golden rule with nasturtiums is to keep them hungry. Plant them in average to poor, well-drained soil and skip the fertilizer, because rich ground gives you a jungle of leaves and very few flowers. Water during dry spells but let the soil dry between drinks. Give trailing types a fence or trellis to climb, or let them spill from a container or over the edge of a bed.

Nasturtiums are a favorite companion in the vegetable garden, working as a living trap crop and a pollinator draw. These four pair especially well, and you can add any of them in one click:

Nasturtiums are a cut-and-come-again edible. Pick the flowers when they are fully open and the young round leaves any time, always leaving plenty behind so the plant keeps producing. For a caper substitute, gather the green seed pods while they are still soft and pickle them. Harvest in the morning for the freshest, most peppery flavor.

Nasturtiums are as useful on the plate as in the bed. The flowers, the round leaves, and the green seed pods are all edible, with a bright, peppery, watercress-like bite. Scatter the blossoms and young leaves over salads for color and spice, and pickle the seed pods as a home-grown caper. In the garden they lure aphids away from your vegetables and pull pollinators in.

• All leaves, no flowers: soil is too rich. Stop feeding and grow them lean.
• Aphids clustering on stems: nasturtiums often draw aphids as a trap crop, so hose them off or leave them to lure pests away from your veggies.
• Yellowing leaves: usually overwatering or heavy soil. Ease off water and improve drainage.
• Slow germination: soak the hard seeds 12 to 24 hours before sowing and plant deep enough for darkness.