Nasturtiums (Tropaeolum majus) are among the most rewarding annuals to grow.
They’re beautiful, edible, and incredibly easy to propagate from seed – making them an excellent choice for beginner gardeners, edible garden enthusiasts, or anyone seeking low-maintenance color.
Whether you’re planting nasturtiums in beds, borders, pots, or hanging baskets, starting them from seed is the most effective and economical way to fill your space with these cheerful bloomers.
In this detailed guide, you’ll learn everything about how to grow nasturtiums from seed, including seed preparation, germination tricks, growing conditions, transplanting tips, and care throughout the growing season.
What Are Nasturtiums?
Nasturtiums are fast-growing, flowering plants native to South and Central America. They’re celebrated for their vibrant orange, red, and yellow blossoms, attractive rounded leaves, and edible flowers and foliage with a spicy, peppery bite.
They’re often used in:
- Pollinator gardens (bees and butterflies love them)
- Edible landscapes (both leaves and flowers are edible)
- Pest control gardens (they repel aphids and whiteflies)
- Container gardens (compact or trailing varieties suit hanging baskets)
- Poor soil spots (they actually thrive in lean, unfertilized ground)
Why Grow Nasturtiums from Seed?
While nasturtiums are occasionally available as transplants, they’re best grown from seed because:
- Seeds germinate easily and quickly
- They grow fast and mature rapidly
- Transplants don’t always survive root disturbance
- You’ll have many more variety options when starting from seed
- It’s more affordable, especially for mass planting
Types of Nasturtiums to Grow
Nasturtiums come in two main forms:
1. Bush/Clumping Varieties
- Stay compact (12–18 inches tall)
- Great for borders, window boxes, and containers
- Popular varieties: ‘Jewel Mix’, ‘Empress of India’
2. Trailing/Climbing Varieties
- Spread or climb up to 10 feet long
- Ideal for hanging baskets, trellises, walls, or groundcover
- Popular varieties: ‘Tall Climbing Mix’, ‘Canary Creeper’
Step-by-Step Guide: How to Propagate Nasturtiums from Seed
1. Choose Your Planting Time
Nasturtiums are sensitive to frost. In most regions, the best time to sow seeds is:
- Outdoors: 1–2 weeks after the last frost date
- Indoors (for an early start): 2–4 weeks before the last frost, then transplant
In warmer climates, you can sow them in early spring or fall, avoiding peak summer heat if possible.
2. Prepare Your Seeds
Nasturtium seeds are large, round, and hard-shelled. They benefit from a bit of pre-treatment to improve germination.
Soak the seeds in warm water for 6–12 hours before planting. This softens the seed coat and allows moisture to penetrate more easily.
You can also gently nick the seed coat with a nail file (scarification), but this isn’t necessary if you soak them.
3. Choose the Right Location and Soil
Nasturtiums prefer:
- Full sun (6+ hours a day for best blooming)
- Well-draining soil
- Lean to moderately fertile soil – too much fertility = fewer flowers and more leaves
They perform well in garden beds, raised beds, or containers, and even tolerate rocky or sandy soil.
4. How to Sow Nasturtium Seeds Outdoors
Direct sowing is the easiest method and typically yields the healthiest plants.
Steps:
- Loosen the soil and remove large clumps or debris.
- Sow seeds ½ to 1 inch deep and cover lightly.
- Space seeds 8 to 12 inches apart for bush types, or 12–18 inches for trailing types.
- Water gently and keep the soil consistently moist but not soggy.
- Expect germination in 7–14 days under ideal conditions.
5. How to Start Nasturtium Seeds Indoors
If you want a head start or live in a region with short growing seasons, you can start seeds indoors.
Steps:
- Use peat pots, biodegradable trays, or individual cell trays to minimize transplant shock.
- Fill with a light, well-draining seed starting mix.
- Plant seeds 1/2 inch deep, one per cell or pot.
- Water and place in a warm, bright location (ideally 65–70°F).
- Germination takes 7–12 days.
- After seedlings grow 2–3 inches tall and have true leaves, harden off before transplanting outside.
Important: Nasturtiums dislike root disturbance, so transplant carefully.
6. Transplanting Outdoors
After the risk of frost has passed and the soil has warmed:
- Choose a sunny location
- Gently transplant your starts into pre-moistened soil
- Space according to plant size: 10–12 inches for dwarf types, 18–24 inches for trailing
Mulch lightly to retain moisture and prevent weeds, especially in hot climates.
Nasturtium Care Tips for Success
Once nasturtiums are established, they require minimal care.
Watering:
- Keep soil evenly moist, especially in the early weeks
- Once mature, they’re fairly drought-tolerant
- Water deeply but infrequently
Fertilization:
- Do NOT over-fertilize
- Too much nitrogen will produce lush foliage but few blooms
- Compost-enriched soil or a light monthly dose of compost tea is sufficient
Light:
- Full sun yields best blooms
- In hotter climates, afternoon shade can help extend the flowering season
Deadheading:
- Remove spent flowers regularly to encourage continuous blooms
- This also prevents unwanted self-seeding
Pest Management:
- Nasturtiums attract aphids and cabbage loopers, but also serve as a trap crop to protect other veggies
- Hand-pick pests or spray with diluted neem oil if infestations occur
- Avoid chemical pesticides as they deter pollinators
Companion Planting with Nasturtiums
Nasturtiums are garden superheroes in companion planting.
They:
- Attract aphids away from brassicas
- Repel squash bugs and whiteflies
- Attract pollinators and predatory insects
Good companions include:
- Tomatoes
- Cucumbers
- Zucchini
- Broccoli
- Kale
- Lettuce
Harvesting and Using Nasturtiums
Harvesting:
- Start harvesting leaves and flowers once plants are well-established (about 6 weeks from sowing)
- Always pick in the morning when flavor and moisture are highest
- Young, tender leaves taste best
How to Use Nasturtiums:
- Edible flowers add a peppery kick to salads
- Leaves can be chopped into pestos, herb butters, or green sauces
- Seeds can be pickled like capers
- Dried flowers make vibrant tea blends or garnish
Every part of the plant (except mature roots) is safe and edible.
Saving Nasturtium Seeds
Nasturtiums are generous self-seeders. If you want to save seeds:
- Allow some flowers to go to seed (avoid deadheading them)
- Collect brown, dried seeds that fall easily from the plant
- Dry completely and store in an airtight container in a cool, dry place
- Label with variety and year
Seeds remain viable for 3–5 years when stored properly.
Troubleshooting Common Nasturtium Problems
| Problem | Cause | Solution |
|---|---|---|
| No flowers | Over-fertilized soil | Reduce fertilizer, avoid rich soil |
| Yellowing leaves | Overwatering or poor drainage | Improve drainage, water only when topsoil is dry |
| Powdery mildew | High humidity and poor airflow | Space plants properly, prune to increase airflow |
| Stunted growth | Crowded roots or cold soil | Thin seedlings, wait for warm temps to sow |
| Aphid infestations | Trap crop effect | Spray neem oil or introduce ladybugs |
Nasturtiums are one of the most beginner-friendly and multi-purpose plants you can grow from seed. With their quick germination, edible beauty, and pollinator-attracting power, they bring both charm and function to any garden space.
