HOW TO GROW NASTURTIUM FROM SEEDS

HOW  TO  GROW NASTURTIUM FROM  SEEDS

Quick-growing summer annuals can add nearly instant color to your garden beds and planters. Nasturtiums (Tropaeolum spp.) produce yellow, orange and red flowers, usually on the same plant. These annual flowers grow readily from large seeds, so you can plant plenty of them with minimal effort and cost. Encourage good sprouting by preparing and planting the seeds correctly.

Planting Time

Nasturtiums grow during the warm, frost-free spring, summer and fall season. Seeds can take up to two weeks to sprout, although they often germinate within seven days if prepared properly before planting. Planting time depends on your climate and whether you start the seeds indoors or outside. Start the seeds indoors about four to six weeks before the last expected spring frost date in your area so the young seedlings are ready to transplant outdoors in spring. If you sow directly in the garden, wait until after the last frost so the tender seedlings aren't killed by cold.

Seed Preparation

The hard, dry seed coating on large nasturtium seeds can slow germination because it's difficult for water to soak into the seed and force it from dormancy. Nicking the seed coat and soaking it in water speeds germination. To nick the seed, scrape one side of it with a metal file until the lighter interior seed coat becomes visible. Soak it in a bowl of warm tap water overnight. The seed absorbs the water through the nicked portion and usually swells to up to twice its previous size. Nicked and soaked seeds require immediate planting; otherwise, they may rot or die.

Indoor Sprouting

A standard sterile potting mix works well for starting nasturtium seeds indoors. Use individual 2- to 3-inch-diameter seedling pots or a larger seedling tray. Pots and trays must have drainage holes so the excess water can drain out. Water the soil before you plant so it's moist. Sow a single seed per pot, or plant the seeds 2 inches apart in rows set 2 inches apart in a tray. Large nasturtium seeds require deep planting, so plant the seeds 1/2- to 1-inch deep in the pots. Keeping the soil temperature near 70 degrees Fahrenheit and maintaining even moisture encourages quick germination. The seedlings won't require light until after they sprout.

Outdoor Sprouting

It's possible to sow nasturtium seeds directly in the garden bed if you prepare the soil first. Nasturtiums have few soil needs. Choose a well-drained bed that receives at least six hours of sunlight daily and work up to 2 inches of compost into it first to improve drainage and quality. Once prepared, plant the seeds 1/2- to 1-inch deep and space them 3 inches apart. The soil will require watering so the top 6 inches remains moist. Once the nasturtiums sprout, thin the plants so they have 8 to 10 inches of space on all sides.