Caption
Bright orange nasturtium flowers with distinctive round leaves. Credit: Pixabay
Planting
When to Plant Nasturtiums
While nasturtium seeds can be sown outdoors anytime after the last spring frost has passed, I usually wait a week or two. The warmer soil helps speed germination, and seeds sprout best when soil temperatures reach 55° to 65°F.
In many areas, you can continue planting nasturtiums throughout the season for a long display of blooms.
You can also start seeds indoors 2 to 4 weeks before your last frost date, but nasturtiums have fragile root systems and don’t transplant well. I usually recommend direct sowing whenever possible.
Where to Plant
Nasturtiums grow well in containers, raised beds, or in-ground gardens, as long as they receive plenty of sun and well-draining soil. Choose a location with well-draining soil and at least 6 hours of direct sunlight daily for the best flowering.
They’re also commonly planted alongside vegetables, including brassicas, cucumbers, melons, and squashes, where they serve as companion plants. Their bright flowers also attract pollinators, including bees, butterflies, and hummingbirds.
Poor soil is actually preferable. Nasturtiums are light feeders, and rich soil often produces lush foliage at the expense of flowers.
How to Plant Nasturtiums
- Prepare the planting area by removing weeds and loosening the soil. If desired, mix a small amount of compost into the top few inches of soil. For containers, use a quality potting mix with good drainage.
- Sow the seeds. Plant seeds 1/2 inch deep and space them 10 to 12 inches apart. Because nasturtium seeds have a hard outer coating, soaking them in water for 8 to 24 hours before planting can speed germination.
- Water thoroughly after planting and keep the soil lightly moist until seedlings emerge.
- Transplant if needed. If you start seeds indoors, harden them off and transplant outside once the risk of frost has past. Just bury the seedlings at the same depth at which they were growing in their nursery pots.
- Add support. If growing trailing or climbing varieties. Install trellises early, so roots aren’t disturbed later.
Pests and Problems
While nasturtiums are relatively tough plants that can handle a range of conditions, they’re not completely immune to problems. Most issues are related to light, heat, or pests rather than serious disease.
Common Problems
- Reduced flowering. If nasturtiums aren’t blooming well, they’re often getting too little sun or too much nitrogen. These plants prefer full light and lean soil. Rich soil produces lots of leaves but fewer flowers.
- Wilting in heat. During hot weather, nasturtiums may droop, especially if the soil dries out. In my experience, they usually bounce back quickly after deep watering or when temperatures cool slightly.
- Leggy or weak growth. Low light can cause stretched, spindly stems. Move plants to a sunnier spot if possible.
- Pest buildup. Because nasturtiums are often used in companion planting near broccoli, cabbages, radishes, and other brassicas, they can attract aphids. I rarely intervene unless infestations become heavy—a strong spray of water is usually enough.
Common Pests
Nasturtiums are often used as trap crops in companion planting, especially near broccoli, cabbages, and other brassicas. Because of this, they commonly attract aphids, and occasionally caterpillars, flea beetles, slugs, snails, or whiteflies.
In most home gardens, pest damage is minor and largely cosmetic. Aphids can be rinsed off with a strong spray of water, and larger insects can be hand-picked.
I usually leave my nasturtiums alone. I find pest issues to be relatively insignificant, and I don’t want to deter pollinators from visiting my plants.
Plant Diseases
Nasturtiums may occasionally develop mosaic viruses, leaf spot, or blight, though serious disease is uncommon in home gardens.
To reduce risk:
- Start with fresh seed from reliable suppliers.
- Avoid reusing old potting mix.
- Rotate planting areas each season.
- Remove plant debris in fall.
Good airflow and well-draining soil go a long way toward preventing problems.
Types
Whether you grow trailing or climbing varieties (Tropaeolum majus) or compact bush types (T. minus), nasturtiums adapt easily to different spaces. I love growing mounding types in pots where their tidy shape shines, while trailing varieties sprawl as cheerful ground covers near melons, cucumbers, pumpkins, and borage.
Flowers range from soft yellows and peach colors to deep reds and oranges. Leaf color can vary too, with some varieties offering attractive variegation.
- ‘Alaska Mix’ features variegated foliage and mixed flower colors, making it a standout in containers.
- ‘Variegatus’ is a trailing type with red or orange blooms, well suited for spilling over edges or climbing supports.
- ‘Peach Melba’ offers creamy yellow flowers with bright orange-red centers for a softer color palette.
More Like This
You can certainly try saving them. Sometimes, nasturtium seeds that have fallen from a plant will make it through the winter to sprout in spring, with no human intervention, so if yours have experienced just a few frosts, and the seed coat is intact, they may indeed be OK. There are no guarantees, of course. (Note that if the original nasturtiums were hybrids, then the offspring may not be like the parent plants.)
Often, mature seeds are found on the ground, after they've fallen off the plant. Green or brown, they may still be viable; in general, the bigger the nasturtium seed, the better chance it will sprout. Collect the seeds, place them on newspaper in a warm place with good air circulation for a few weeks to dry; any greenish seeds will turn brown. Discard any seeds that develop mold. Then, place the dried seeds in an airtight jar, label and seal, and store in a dark, cool place until spring, when you can plant them after frost and see if they come up. (Just before planting, you might want to soak the seeds in water overnight to encourage germination. This softens the hard seed coat.)
Good luck!
Yes, you can pick the green seeds. Pick the largest seeds for better germination in the spring. Put the seeds on a paper towel to dry. As the seeds dry they turn tan or brown. When dry put them in an airtight container or paper envelope and store in a cool dark place.
No, in zones with freezing temperatures such as MA, wait until after the frost; in the mild southern climates, they can be planted in the fall for “winter” blooming.
Use the spacing suggested above--or on your seed packet to determine the size you want. Just make sure the container has drainage holes and use a soilless media for container growing. We like 50% peat and 50% perlite.
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