Yes, nasturtium is easy to grow from seed right now, and you can sow or refresh plants this weekend to start harvesting flowers and leaves within weeks.
I plant nasturtiums every year. They tolerate poor soil and give fast color. Read on and you will have exact seed counts, pot sizes, soil mixes, watering amounts, pest checks, and harvest tips to act on this weekend.
What to buy, exact seed counts pot sizes and soil for nasturtium
Seed counts, sowing rate per 10 foot row, per 4 by 4 raised bed, per 12 inch pot
- 10 foot row, upright types, 6 inch spacing: 20 seeds. For 8 inch spacing: 15 seeds.
- 10 foot row, trailing types, 8 inch spacing: 15 seeds. For 12 inch spacing: 10 seeds.
- 4 by 4 raised bed (16 square feet): upright types, 12 to 20 plants. Trailing types, 8 to 12 plants. Sow 25 percent extra seeds to allow for missed germination.
- 12 inch pot: 1 upright plant, or 1 to 2 trailing plants (2 seeds, thin to the healthiest seedling).
Buy whole packets of seed. A typical packet has 50 to 100 seeds. One 50 seed packet is enough for three 10 foot rows or several pots and a small bed.
Pot sizes and soil mix recipe, quantities in quarts and cups
- Containers, upright: 6 to 8 inch pot (1 to 2 gallons) for a single upright plant.
- Containers, trailing: 12 inch pot (about 5 gallons, roughly 20 quarts) for 1 to 2 trailing plants.
- Hanging basket: 10 to 12 inch, 5 to 8 gallon volume, 20 to 32 quarts.
Mix per 1 gallon of potting mix, then scale up to fit your pot size.
- Per 1 gallon mix (4 quarts): 3 quarts sterile potting mix, 1 quart finished compost, 1/4 cup perlite or coarse sand.
- For a 12 inch pot (5 gallon, about 20 quarts): 15 quarts potting mix, 5 quarts finished compost, 1 and 1 quarter cups perlite. That is 60 cups potting mix, 20 cups compost, 1.25 cups perlite.
Keep the mix light and free draining. Nasturtiums bloom best in leaner mixes, so do not add high nitrogen fertilizer to the potting mix.
Recommended varieties by use, for flavors and trailing versus upright habit
- For salads and edible flowers, try ‘Alaska’ or ‘Ladybird’, they have milder flavor and compact habit.
- For big, showy trailing habit on a fence or basket, use ‘Jewel Mix’, ‘Empress of India’, or ‘Russian Red’.
- For upright, bushy plants good for cutting and small beds, use ‘Whirlybird’ or ‘Tall Mixed’.
- If you want a peppery bite from leaves, pick half-hardy cultivars like ‘Tropaeolum majus’ varieties listed above, they all vary slightly in heat and flavor.
How to prepare beds and containers for nasturtium, drainage and soil detail
Soil pH and fertility targets, how much compost or low nitrogen amendment to add per square foot
Target soil pH 6.0 to 7.5. If your pH is outside that range, use a soil test and follow local extension recommendations.
- Do not over-fertilize. Nasturtiums bloom better in low fertility. Add only 1 cup finished compost per square foot of bed, mixed into the top 3 inches.
- Avoid adding high nitrogen fertilizers. If you want a slow feed, use a low nitrogen organic fertilizer labeled for flowers, applied at half the suggested rate.
How to adjust for heavy clay, raised beds, and pure potting mix
Heavy clay, the common failure mode is waterlogging and rot. I lost a bed to rot the year I skipped raised rows, so drainage comes first.
- For heavy clay, loosen soil and mix in 2 inches of finished compost per square foot and 1 to 2 quarts per square foot of coarse sand or horticultural grit. If clay is severe, plant in a 6 inch raised row or bed.
- Raised beds: fill with the potting-style mix above. Ensure a minimum 10 inch soil depth for trailing roots.
- Pure potting mix in containers: fine. Keep pots on saucers or feet to allow drainage and never let pots sit in standing water.
Use a hand trowel to check drainage. If water clings and the soil stays wet for days, improve drainage before planting.
How to sow and transplant nasturtium, step by step with depths and spacing
Direct sow method, exact planting depth and spacing for trailing and upright types
- Wait until soil warms above 50F for steady germination, and after hard frosts have passed if you are in a cold zone. Soil temperatures 55F to 70F give reliable germination.
- Sow seeds 1/2 inch to 1 inch deep. Larger seeds can be placed at 3/4 inch and covered with loose soil.
- Spacing: upright types 6 to 8 inches apart, trailing types 8 to 12 inches apart. In a 10 foot row, follow the seed counts above.
- Water the row with a gentle soak equal to 1 inch over the bed, then keep surface just moist until seedlings emerge in 7 to 14 days.
When and how to start indoors, pot sizes, timings tied to frost dates
I usually do not start nasturtiums indoors, they resent root disturbance. If you must, start 3 to 4 weeks before the last expected frost and use peat pots or biodegradable cups.
- Use 2 to 3 inch pots for seedlings, one seed per pot.
- Start indoors at 60F to 70F soil temp. Keep seedlings in bright light or a sunny south window.
- Move seedlings outside only after nights are consistently above 40F, and preferably after your last frost date.
How to transplant seedlings without shock, hardening off schedule linked to last frost
- Harden off for 7 to 10 days before transplanting: start with 2 hours outside on day one and add 1 to 2 hours each day.
- Plant while soil is moist. Dig a hole the same depth as the pot; set the whole peat pot into the hole if used, or loosen the root ball gently.
- Water immediately with 1 quart per 4 inch pot seedling, or 1 gallon for a 12 inch pot. Keep evenly moist the first week while roots establish.
Midsummer care, deep watering pruning and heat stress for nasturtium
How much to water, frequency and soak amount in cups or gallons for raised bed and pots
In midsummer heat, nasturtiums need regular deep soaks but do not like standing water.
- 4 by 4 raised bed: give 1 inch of water per week as a baseline. For a 16 square foot bed, that equals about 10 gallons per week. In heat waves, split into two soaks of 5 gallons each.
- 12 inch pot (5 gallon): water thoroughly until water drains from the bottom, about 1.5 to 2 gallons per watering, roughly 6 to 8 quarts. In heat, water every 2 to 4 days depending on sun exposure and wind.
- 6 to 8 inch pot (1 to 2 gallons): about 2 to 4 quarts per watering, every 2 to 5 days in heat.
Use a soil probe or finger to check 2 inches below the surface before watering.
Recognizing heat stress, when to provide afternoon shade or move containers
Heat stress signs: wilting in late afternoon, scorched leaf edges, flowers dropping. If highs hit 90F for several days or more, provide 30 percent to 50 percent shade during afternoon, or move containers to afternoon shade or an east facing spot.
Light trimming and pinch back to prolong bloom and reduce bolting
- Pinch back growing tips on young plants to encourage branching and more flowers.
- Remove spent flowers twice weekly to keep plants blooming. Cut back up to one third of overly leggy growth to refresh the plant.
- Do not over-prune in late season, it reduces seed set if you depend on saving seeds.
Pest patrol and disease care for nasturtium, natural control steps
How to inspect for aphids caterpillars and flea beetles, what to remove by hand and how often
Inspect plants twice weekly. Look under leaves and in flower centers.
- Aphids, remove clusters with a hard stream of water or wipe with a damp cloth. Check every 3 to 5 days until controlled.
- Caterpillars, pick off by hand in the morning. Dispose in soapy water. Check daily during outbreaks.
- Flea beetles, use floating row cover early or knock beetles into a jar of soapy water. Inspect weekly because flea beetle damage appears fast.
When nasturtiums are a trap crop, and when they actually attract more pests to other plants
Nasturtiums can act as a trap crop for aphids and flea beetles, drawing them away from brassicas and beans. Plant nasturtiums a few feet from valuable crops and monitor them closely. If nasturtiums become heavily infested they can become a pest source. Pull infested plants or treat them before pests spread to main crops.
Simple sprays and cultural fixes to try, and when to call your extension for pesticides
- Soap spray: mix 1 to 2 tablespoons mild liquid castile or dish soap per quart of water, spray undersides and tops, repeat every 3 to 5 days as needed.
- Neem or insecticidal soap labeled for edible plants can help for soft bodied pests, follow label directions.
- Cultural fixes: increase air flow, avoid overhead watering late in the day, remove heavily infested foliage.
Call your local extension office for pesticide recommendations and local rules if you reach the point where organic controls fail. They will give application timing and product names suited to your county.
Harvesting nasturtium, storing flowers leaves and seeds, edible uses
When to pick flowers and
Pick flowers in the morning when they are fully open. Flowers keep best if used the same day, but will refrigerate for 24 hours in a plastic container with a paper towel.
- Leaves, pick young leaves for the mildest peppery flavor. Store in the refrigerator wrapped in a damp paper towel, use within 3 to 5 days.
- Seeds, harvest when pods turn brown and dry on the plant. Shell and lay seeds on a paper towel to dry for 7 to 10 days before storing in a paper envelope in a cool dry place.
- Seeds can be pickled like capers. Rinse, blanched 30 seconds, then brine and jar according to a tested recipe.
Edible uses: flowers garnish salads, leaves add peppery zip to sandwiches and pesto substitutes, seeds make a caper-like condiment. I use two flowers per salad bowl for color and one or two young leaves per serving for flavor.
| Action | Timing relative to last frost | Soil temp for best results |
|---|---|---|
| Direct sow | After last frost to 8 weeks before first frost | 55F to 70F |
| Start indoors | 3 to 4 weeks before last frost | 60F to 70F |
| Refresh sowing | Midsummer, while cooler nights persist | Above 55F |
For raised beds, see my step by step guide to raised bed gardening for beginners. For container water timing tips in summer, read when to water vegetable plants in summer. If you plan containers like I do for tomatoes and nasturtiums together, check how to grow tomatoes in containers. For companion planting ideas, pair nasturtiums with herbs from best herbs for small backyard gardens. If you are new and want to avoid the most common traps, read common mistakes new gardeners make.
FAQ heading
Can I sow nasturtiums now in midsummer?
Yes, you can sow nasturtium seeds in midsummer as long as nights are not regularly dropping below 50F and soil is not baking at 95F or more. In zone 6b you will get good results sowing into lightly shaded spots or late afternoon sun from now through early August.
Do nasturtiums need fertilizer?
No heavy feeding. Too much nitrogen makes lots of leaves and few flowers. Add only 1 cup finished compost per square foot, or a low nitrogen flower feed at half strength once in mid season if growth looks weak.
How often should I deadhead nasturtiums?
Remove spent flowers two to three times a week during heavy bloom. Frequent deadheading keeps plants productive and reduces seed set if you want continuous flowers rather than seeds.
Are nasturtiums poisonous to pets?
Nasturtiums are generally considered non toxic, but pets eating large amounts can get an upset stomach. Check with your veterinarian if your pet shows symptoms after chewing plants.
Can nasturtiums be used as a trap crop?
Yes, they attract aphids and flea beetles away from brassicas and beans. Plant them a few feet away and inspect regularly. If the nasturtiums become heavily infested, remove or treat them so pests do not spill back onto valuable crops.
