Nasturtiums are a vibrant addition to any garden, cherished for their cheerful, often peppery-flavored leaves and flowers. These versatile plants offer both ornamental beauty and edible components, making them a favorite among home gardeners. Their relatively straightforward propagation methods make them accessible even for those new to gardening, providing a rewarding experience as you cultivate new plants from existing ones.
Seed Propagation
Seed propagation is common and effective. Seeds can be collected from dried flowers or purchased. Nasturtium seeds have a hard outer coat that benefits from preparation to germinate quicker. Scarification, nicking the seed coat or rubbing it with sandpaper, allows water penetration. Alternatively, soaking seeds in lukewarm water overnight softens the coat.
Once prepared, nasturtium seeds can be sown directly outdoors after the last frost, when soil temperatures reach 55-65°F (12-18°C). Plant seeds about 1/2 to 1 inch deep and space them approximately 10 to 12 inches apart for ample growth. If starting indoors for an earlier bloom, sow seeds in biodegradable pots two to four weeks before the last expected frost, which minimizes transplant shock. Keep the soil consistently moist but not waterlogged during this period. Germination typically occurs within 7 to 10 days under ideal conditions, revealing new nasturtium life.
Cuttings Propagation
While seed propagation is common, nasturtiums can also be propagated from cuttings to preserve specific plant characteristics. Select a healthy, non-flowering stem section 4 to 6 inches long from a mature nasturtium plant. Cut just below a leaf node, where roots are likely to form. Remove leaves from the lower two-thirds of the cutting to prevent rot in water or soil.
Cuttings can root in either water or a well-draining potting mix. For water rooting, place prepared cuttings in a jar, ensuring no leaves are submerged. Change the water every few days to maintain freshness.
For soil rooting, insert the cut end into moist, well-draining potting mix, burying at least one node. Rooting hormone is optional. Place cuttings in indirect light and maintain consistent moisture. New leaf growth within weeks indicates successful rooting.
Post-Propagation Care
Once seedlings or rooted cuttings have developed a robust root system, they are ready for transplanting. Handle young plants gently, as their root systems are delicate. If starting seeds indoors, gradually acclimate them to outdoor conditions (7-10 days) before transplanting to reduce shock. Plant nasturtiums in full sun (6-8 hours daily), though they can tolerate partial shade, especially in hotter climates.
Nasturtiums thrive in well-draining, average to poor soil, with a neutral pH between 6 and 8. Overly rich soil can lead to abundant foliage at the expense of flower production.
Water newly transplanted nasturtiums thoroughly to settle the soil. Established plants prefer consistent moisture (about an inch per week), but avoid overwatering to prevent root rot. While generally resilient, nasturtiums can attract aphids, which are often dislodged with a strong water spray. Regular inspection helps address issues promptly.