EASY TO START OUTDOORS: Sow seeds in spring once all danger of frost is over in full sun (or part shade in hot climates). Nasturtiums need no added fertilizer in most soils. Poke seeds into well-worked soil about 1 inch deep and 3 to 4 inches apart. Press soil firmly over the seeds and keep moist. When seedlings are large enough to handle, thin 10 to 12 inches apart so plants will have ample room to grow.
TO START EARLY INDOORS: Sow 2 seeds each in individual 4-inch pots of well-drained seed starting mix 3 weeks before last expected frost date. Cover 1 inch deep. Provide a strong light source. When seedlings have several sets of leaves, pinch out the weaker seedling leaving 1 seedling per pot. When weather is evenly in the 50°F (10°C) range, gradually acclimate to outdoor conditions. Transplant 10 to 12 inches apart in full sun.
GROWING NOTES: Climbing nasturtiums are easy to grow in any well-drained soil. You’ll need to train young plants onto their supports with loose ties, then they’ll climb easily and bloom non-stop. Do not let plants dry out during blooming season. Spitfire’s glowing blossoms are summer beacons for hungry hummingbirds.