Nasturtium Seeds
When should I plant
Nasturtium seeds can be planted in early spring after the last frost date when soil temperatures reach around 55–65°F. They thrive in cool to mild weather and can tolerate light frosts. In warmer climates, they can also be sown in late summer or early fall for autumn blooms, as they prefer cooler growing conditions over extreme heat.
Spring Sowing
For spring planting, sow seeds directly outdoors 1–2 weeks after the last expected frost. Nasturtiums dislike root disturbance, so direct sowing is preferred over transplanting. The soil should be workable and not too cold, as germination may be delayed in chilly conditions. Spring-sown nasturtiums will bloom from early summer into fall.
Fall Sowing
In mild-winter regions, fall sowing is ideal for extended blooms. Plant seeds in late summer to early fall, allowing enough time for plants to establish before cooler temperatures set in. Fall-sown nasturtiums may continue flowering through winter in frost-free areas, providing vibrant color when other plants fade.
Site consideration
Nasturtiums grow well in poor to average, well-draining soil. Rich soil promotes excessive foliage at the expense of flowers. They can be planted in garden beds, containers, or hanging baskets.
Water
Water nasturtiums moderately, allowing the soil to dry slightly between waterings. Overwatering leads to lush leaves but fewer blooms, while drought stress can cause wilting and reduced flowering. Once established, they are somewhat drought-tolerant. Container-grown plants may need more frequent watering than those in the ground.
Sunlight
Nasturtiums prefer full sun (6+ hours daily) for optimal flowering but tolerate partial shade, especially in hot climates where afternoon shade can prevent scorching. In too much shade, plants become leggy and produce fewer blooms. Morning sun with light afternoon shade is ideal in warmer regions.
Seed Germination
Seeds typically germinate in 7–10 days. Soaking seeds in water for 12–24 hours before planting can speed up germination. Plant seeds ½ inch deep and space them 10–12 inches apart. Keep the soil moist but not soggy until seedlings emerge. Thin seedlings if they are overcrowded to ensure healthy growth.
Seeding Rate
1oz Covers 20 sq.ft. Nasturtiums grow quickly, so avoid overplanting.
Other Elements
Fertilization
Avoid high-nitrogen fertilizers, which encourage leafy growth over flowers. If soil is very poor, a light application of balanced, low-strength fertilizer at planting is sufficient. Compost or organic matter can improve soil structure without overfeeding. Excess nutrients reduce blooming.
Weed control
Mulching with straw or shredded leaves helps suppress weeds and retain moisture. Hand-pull weeds early to avoid competition, especially when seedlings are young. Nasturtiums’ dense foliage can eventually shade out weeds, making them low-maintenance once established.
Seed Storage
The seeds will maintain a high germination percentage if stored under proper conditions. How long your seeds remain viable will depend on the temperature and moisture levels the seeds are exposed to. Seeds which are improperly stored will quickly deteriorate if unprotected against high humidity and dramatic temperature fluctuations day after day.
For best results, keep the seed in our moisture-proof ziplock sealing bags, which provide a better moisture prevention effect. Glass jar or plastic containers with snap-on lids works well too, add a packet of desiccant before sealing into the seed, such as silica gel to remove any moisture remains in the storage container. Seed stored under these conditions will remain viable for as long as years.
Factors Which commonly Cause Poor Results
1. Improper drainage soil
2. Sowing depth more than one inch
3. Covering the seed too deep beneath the soil surface
4. Cover a large area with a small amount of seed.
5. Plant at a wrong time of a year
6. Lack of sunlight
7. Inadequate rainfall after seed germination. The area should not be allowed to become completely dry. Supplemental watering may be required to sustain plant life.
8. Extreme weather conditions: hail, drought, excessive rainfall, floods, unseasonably cold temperatures.