Nasturtiums are valued for their vibrant flowers, attractive foliage, and edible peppery taste. Achieving successful germination often involves a simple preparatory step before the seeds are placed in the soil. This pre-treatment helps overcome a natural barrier, ensuring the seeds begin the growing process more quickly.
Understanding Why Nasturtium Seeds Need Preparation
Nasturtium seeds benefit from preparation due to their tough and thick outer layer, known as the seed coat or testa. This coat acts as a protective shield, preventing premature germination in unfavorable conditions. However, this dense layer restricts the necessary absorption of water. A seed must take in water, a process called imbibition, to trigger the metabolic changes that signal the start of germination. Softening or breaching this coat allows water to penetrate the seed more easily, significantly improving the speed and rate of sprouting.
Optimal Soaking Times and Technique
Soaking is the simplest and most common method used to help break the hard seed coat. The recommended duration for soaking nasturtium seeds is between 12 and 24 hours. Soaking for a full overnight period is effective for maximum benefit.
The process involves placing the seeds in a container of lukewarm water to help soften the testa. If soaking for 24 hours, changing the water after the first 12 hours ensures the water remains fresh. The seeds are ready to be planted when they appear visibly plump and slightly swollen, indicating successful water absorption.
Another technique is scarification, which involves lightly scratching or nicking the seed coat. This method physically creates a breach for water entry but requires care to avoid damaging the inner seed membrane. Soaking remains the less labor-intensive and more common preparatory method.
Planting Seeds After Soaking
Once the nasturtium seeds have completed soaking, they should be planted immediately. Allowing them to dry out can reduce the effectiveness of the pre-treatment. The softened seeds are ready to be sown directly into the garden or into containers.
Plant the seeds approximately 1/2 to 1 inch deep in the soil. This depth ensures the seeds are covered enough to maintain moisture. Seeds should be spaced about 8 to 12 inches apart to give the plants room to grow and spread.
After placing the seeds, gently firm the soil over them and water the area well. Nasturtiums germinate best when the soil temperature is consistently warm, ideally between 70 and 75°F. Consistent moisture and warmth encourages the seeds to emerge, which occurs within 10 to 14 days.