Growing Nasturtiums from Seed: A Complete Beginner's Guide
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Nasturtiums are the rare flower that thrives on neglect. They germinate readily, grow fast, bloom from summer to frost, and — unlike most flowers — actually prefer poor soil. Their bright, peppery flowers and lily-pad leaves are edible too, making them as useful in the kitchen as they are cheerful in the garden.
What You'll Love About Growing Nasturtiums from Seed
Nasturtiums are one of the easiest flowers a beginner can grow from seed: big seeds that are simple to handle, sprouts in about a week, and flowers in every warm shade of red, orange, and yellow. Trailing types spill beautifully from hanging baskets and window boxes, while bush types make bright, informal edging. The flowers and young leaves have a peppery, watercress-like flavor prized in salads. Gardeners also plant them as companions in vegetable beds, where they are traditionally used as a trap crop that draws aphids away from other plants. For another unfussy summer bloomer, see our guide to growing marigolds from seed.
How to Sow Nasturtium Seeds
When to sow
Sow after all danger of frost has passed, when the soil has warmed to roughly 55°F to 65°F. Nasturtiums prefer cooler germination conditions than heat-lovers like zinnias, and sowing can continue from mid-spring into early summer. Direct sowing is strongly preferred — nasturtiums dislike root disturbance, so if you start them indoors, use biodegradable pots and transplant very young.
Planting depth and spacing
Sow seeds 1/2 inch deep: nasturtium seeds need darkness to germinate, so make sure they are fully covered. Space seeds 8 to 12 inches apart for bush types (thin seedlings to the strongest), and give trailing or climbing types more room to sprawl. Soaking seeds for a few hours or overnight before planting can improve germination. Expect sprouts in 7 to 14 days depending on soil warmth.
Soil and sun requirements
This is the delightful exception to most gardening advice: plant nasturtiums in poor to average, well-drained soil, and do not enrich the bed. Rich soil and fertilizer produce enormous leaves with hardly any flowers — the number one disappointment with nasturtiums. Full sun gives the heaviest bloom, though they tolerate partial shade with somewhat fewer flowers. Find bush and trailing types in our flower seed collection.
Caring for Your Nasturtium Plants
Watering
Water regularly through the growing season, especially while plants are young. Once established, nasturtiums tolerate dry spells, but consistent moisture keeps them blooming strongly. Take care not to overwater — soggy soil invites rot, and these plants genuinely prefer life on the drier side.
Feeding
Don't. Seriously — with the exception of extremely poor, sandy ground, fertilizing nasturtiums does more harm than good, pushing leaf growth at the expense of the flowers you planted them for. If your plants are all foliage and no blooms, excess fertility is the likely culprit.
Harvesting and deadheading
Pick flowers regularly for salads and garnishes — harvesting is itself a form of deadheading, and it keeps new buds coming. Removing spent blooms before they set seed prolongs flowering well into fall. If aphids cluster on the growing tips (nasturtiums' role as a trap crop in action), a strong jet of water dislodges them, or simply snip off the affected tip.
Common Mistakes to Avoid
- Planting in rich, fertilized soil. This is the classic nasturtium mistake: lush leaves, no flowers. Lean soil is the goal.
- Sowing too shallow. Seeds need darkness — a full 1/2 inch of cover.
- Transplanting carelessly. Direct sow where they are to grow, or use pots you can plant whole.
- Too much shade. They will grow in part shade but bloom far better in sun.
- Overwatering. Steady moisture yes, swampy soil no.
Final Thoughts
Nasturtiums flip the usual gardening script: the less you pamper them, the better they perform. Sow in ordinary soil, hold the fertilizer, pick the flowers for your salads, and enjoy one of the longest, brightest bloom seasons of any annual — all the way to frost.