Understanding when to start nasturtium is essential for harnessing their potential as both a vibrant garden addition and a functional culinary herb. These cheerful, edible flowers thrive in poor soil and full sun, making them remarkably adaptable for a range of climates. The timeline for success depends heavily on your specific goals, whether you are aiming for an early spring bloom, a continuous summer harvest, or a late-season display of fiery color.
Direct Sowing vs. Indoor Starting
Because nasturtiums possess a robust taproot, they resent transplantation and perform best when direct sown into their final location. The optimal window for direct seeding is after the danger of frost has passed and the soil has warmed to at least 55°F (13°C). In most temperate climates, this typically falls between late spring and early summer. Sowing seeds directly into the ground ensures strong root development and minimizes the shock that often accompanies moving delicate seedlings.
Starting Nasturtiums Indoors
For gardeners eager to get a jump on the season, starting nasturtium seeds indoors 2 to 4 weeks before the last expected frost date is a viable strategy. Use biodegradable pots, such as peat or coir, to facilitate root disturbance-free transplanting. Fill the pots with a lightweight, well-draining seed-starting mix and plant the large seeds about 1/2 inch deep. Maintain consistent moisture and provide bright, indirect light to prevent the seedlings from becoming leggy before they are moved outdoors.
Climate and Temperature Considerations
Nasturtiums are celebrated for their resilience, tolerating a surprisingly wide range of conditions. They are categorically not frost-hardy and will succumb to freezing temperatures, which is why waiting for stable warmth is critical. Conversely, extreme summer heat can sometimes cause them to pause flowering. In regions with particularly hot summers, they often perform best with a little afternoon shade or strategic planting where they can cool off as the day progresses.
| Planting Method | Timing | Best For |
|---|---|---|
| Direct Sowing | After last frost, soil 55°F+ | Strong root systems and low-maintenance gardens |
| Indoor Starts | 2-4 weeks before last frost | Extended growing seasons and earlier blooms |
Soil and Site Selection
The question of when to start nasturtium is intrinsically linked to the condition of the soil. These plants thrive in lean conditions; overly rich soil, particularly high in nitrogen, promotes lush foliage at the expense of flowers. Prior to planting, choose a location that receives a minimum of 6 hours of direct sunlight daily. Amend the soil lightly only if it is exceptionally heavy clay, incorporating a small amount of sand or gravel to ensure excellent drainage to prevent root rot.
Succession Planting for Continuous Blooms
To enjoy a constant supply of vibrant blossoms and peppery leaves, consider staggering your planting times. If you have a long growing season, you can make successive sowings every 2 to 3 weeks. This approach ensures that as the first wave of plants begins to decline due to heat or disease, a fresh batch of seedlings is ready to take over, providing a continuous display of color and harvest through the summer months.
Harvesting and Utilization Timeline
Once established, nasturtiums develop rapidly, offering value in multiple ways. You can begin harvesting the tender leaves and flowers approximately 60 days after sowing. Both the flowers and leaves are edible, delivering a peppery, radish-like flavor that brightens salads and garnishes. By understanding the growth cycle and planting at the right time, you ensure that the plant is mature enough to handle regular picking without sacrificing its ornamental vitality.
