Harvesting Nasturtium Seeds: Step-by-Step Guide for Next Year’s Blooms

Harvesting nasturtium seeds is the secret to free, vibrant blooms next spring—no store-bought packets needed. 🌻 I’ve saved seeds for years, and the difference between last year’s scraggly plants and this year’s lush, continuous blooms comes down to timing and technique.

Nasturtiums reward patience with a bounty of peppery edible flowers and seeds that sprout reliably.

The key moment arrives when those round, pea-sized seed pods turn from green to papery brown—usually 6-8 weeks after flowering. Snip them off with clean scissors (or just pinch them off) before they split open and scatter seeds everywhere.

A small paper bag over the stems catches any stragglers, but most pods stay closed long enough to dry indoors.

Once dry, crack open the pods to find plump, flat seeds that’ll last 3-4 years if stored in a cool, dark place. These aren’t just pretty—they’re edible too, with a spicy kick perfect for salads or garnishes.

Plant them shallowly next spring, and you’ll have blooms in 4-6 weeks, outpacing anything from a nursery.

Here’s the thing—nasturtiums self-sow aggressively if you let them. That’s why harvesting seeds gives you control: stronger plants, better growth habits, and flowers that last all season. Plus, you’ll save money and avoid the disappointment of store-bought seeds that don’t perform like the ones you grew yourself.

What you need

How to harvest nasturtium seeds for future plantings

Here's my foolproof method for collecting seeds that guarantee vibrant blooms next season.

Wait until the first frost has blackened and dried the nasturtium foliage—this signals the plant has finished its cycle. Look for seed pods that have turned from green to papery brown and feel dry to the touch. These pods are ready for harvesting, while green ones are still developing.

Gently twist each pod between your fingers until it releases its seeds. I find it easiest to do this over a clean white paper bag so I can see the seeds fall and catch any stragglers. Avoid pods that look shriveled or moldy—those won’t produce viable seeds for next year.

Spread the collected seeds on a flat surface like a baking sheet or clean towel. Let them dry in a warm, dry place (around 70-75°F) for 3-5 days. This prevents mold growth and ensures proper seed viability. Stir them occasionally to prevent clumping.

Once fully dry, separate the seeds from any remaining plant debris. Nasturtium seeds are flat and peanut-shaped, so I use my fingers to pick out any chaff or empty pods. A fine-mesh strainer helps remove dust and tiny fragments while keeping the seeds intact.

Transfer the clean seeds into a small envelope or airtight container. I label each with the variety name and the harvest year—next season’s planting will be easier when you don’t have to guess which seeds are which. Store them in a cool, dark place (like a pantry or seed drawer) where temperatures stay below 60°F.

Nasturtium seeds remain viable for 2-3 years if stored correctly. Check them annually—discard any seeds that look discolored or shriveled. For extra protection, place a silica gel packet in the container to absorb excess moisture and prevent spoilage.

Before committing to a full planting next spring, test a few seeds to confirm germination. Plant 3-4 seeds in a small pot with moist potting mix, cover lightly with soil, and place in a warm spot (around 65-70°F). Keep the soil consistently moist but not soggy.

Germination should occur within 7-14 days. If fewer than half sprout, your seeds may have lost viability, and you’ll want to save fresh ones for future harvests. Healthy seeds will produce sturdy seedlings with deep green leaves—a sure sign they’re ready for transplanting.

Tips & tricks for perfect nasturtium seed harvesting

A few simple tricks will help you maximize seed viability and save time during each step of the process.

Pod Selection Tip: In Step 1, when identifying those papery brown pods, give them a gentle squeeze—they should feel hollow inside. If they're still firm or crunchy, they're not ready yet. I've learned the hard way that harvesting too early means collecting underdeveloped seeds that won't sprout properly. Also, focus on pods from the healthiest plants—they'll produce the most vigorous seeds for next year.

Drying Strategy: During the 3-5 day drying period in Step 2, place your seeds in a location with good airflow, like near an open window with a fan blowing gently. The 70-75°F temperature range is ideal, but avoid direct sunlight which can cause uneven drying. I like to stir my seeds every 12 hours to prevent clumping—this ensures all seeds dry uniformly and reduces the chance of mold growth.

Storage Wisdom: For long-term storage in Step 3, consider using small glass jars with tight-sealing lids instead of envelopes. The cool, dark place should ideally be around 60°F—a refrigerator works perfectly if you don't have a dedicated seed drawer. I've found that placing a small packet of silica gel in the container creates an extra moisture barrier, which is especially helpful in humid climates. Labeling with both the variety name and harvest year saves headaches when you're ready to plant next spring.

Germination Test Hack: When testing your seeds in Step 4, use clear plastic cups instead of pots so you can easily monitor root development. The 65-70°F warm spot works best if you place the cups on top of your refrigerator or near a sunny window. I've noticed that seeds planted in moist but not soggy soil sprout more consistently—think of it like a damp paper towel rather than a wet sponge.

Frequently asked questions

When is the best time to harvest nasturtium seeds?

Harvest seeds when the seed pods turn papery brown and start splitting open naturally—usually 6–8 weeks after flowering. If left too long, seeds scatter, making collection messy. Aim for late summer to early fall in most climates. Pro tip: Pick pods in the morning when humidity is low for easier handling!

How do I know if my nasturtium seeds are mature enough?

Mature seeds are dark, firm, and plump inside the pods. If you gently squeeze a pod and it crinkles (like dry paper), it’s ready. Avoid harvesting green or soft pods—they won’t store well. Test one: Squeeze a seed between your fingers; it should feel dense, not hollow.