Ornamental · Tropaeolaceae
Nasturtium
Tropaeolum majus
Give it poor soil and full sun, and this easygoing nasturtium rewards you with peppery leaves and bright, edible flowers all summer long.
Full sun
50–86°F · 10–30°C
35–50 days
USDA 2–11
Overview
Nasturtium is one of the kindest plants you can grow, a fast, cheerful annual loved for its edible flowers and peppery leaves. Depending on the type you choose, it will climb, trail, or mound, and those round leaves and warm-toned blooms have charmed cottage gardeners for generations. The whole plant carries a fresh, watercress-like bite that finds its way into salads and onto the plate as a pretty garnish.
The best part, especially if you are just starting out, is how little it asks of you. Where most plants beg for feeding and rich ground, a nasturtium is happiest in lean, poor soil with nothing added at all. Spoil it and you will get a tumble of leaves and few flowers, so the real trick is to plant it and let it be.
It gives back in more ways than looks, too. Aphids and cabbage caterpillars find it irresistible, and clever gardeners turn that to their advantage by growing it as a trap crop that gently pulls those pests off nearby vegetables.
Care
The short version: give it full sun and lean, well-drained soil with no fertilizer at all. Water enough to keep young plants comfortable, then let settled plants dry a touch between drinks, and sow the seeds right where they will grow instead of moving them.
Light
Give your nasturtiums full sun and they will flower at their happiest. They will still grow in part shade, but you will get more leaves than blooms, so hand them the sunniest spot you have and they will thank you.
Water
While young plants are settling in, keep the soil lightly and evenly moist so they never feel stressed. Once they have found their feet in lean, well-drained ground, they take short dry spells in stride, so let the top inch dry before you water again. The only thing to steer clear of is waterlogged soil.
Soil
This is a plant that quietly thrives on being left alone. Offer it lean, well-drained loam or sandy soil of poor to average fertility, and hold back the rich compost. Fertile ground is the surest way to end up with leaves in place of flowers.
Temperature
Nasturtiums are content between 50°F and 86°F (10°C to 30°C), so most gardens suit them well. They are tender annuals with no frost tolerance, so let the cold pass before sowing and expect them to bow out at the first hard frost.
Humidity
Everyday outdoor humidity is plenty, with no number for you to chase. Good airflow matters more than moisture in the air, since crowded plants invite the aphids this one already draws in.
Feeding
You can simply skip the feeding, and that makes life easier. Nasturtiums flower best in hungry soil, and any nitrogen-rich fertilizer will leave you with a leafy plant and almost no blooms.
Pruning
There is very little to do here beyond a bit of deadheading. Pinch off the spent flowers to keep fresh ones coming, and clear away any damaged or diseased growth whenever you notice it.
Size & spacing
Plants run from about 12 inches (30 cm) on the bushy dwarfs to 10 feet (3 m) on the climbers, so check your type before you settle them in. Let trailing forms wander and offer the tall ones something to climb.
When to plant
Nasturtiums grow quickly and simply cannot take frost, so there is no rush and no guesswork. Wait for the spring frost to pass, tuck the seeds into warm soil, and the plants will flower from early summer all the way to the first fall frost.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Optional, 2 to 4 weeks before the last spring frost in biodegradable pots; resents root disturbance.
- Plant: Direct sow after the last spring frost once soil has warmed; dislikes transplanting.
- Harvest: Blooms early summer until the first fall frost.
Hardiness
USDA hardiness zones: 2–11
Temperature: down to -46°C
Troubleshooting
Most nasturtium trouble shows up either as pests on the leaves or a plant that grows lush but holds back its flowers, and both are gentle to fix. You will find each one easy to spot once you know what you are looking at. Match what you see below, then act early and it rarely spreads.
Sticky leaves and crowds of tiny insects on the shoot tips
Take heart if you find aphids gathering here, because it happens to nearly everyone and it rarely means you did anything wrong. In fact this plant welcomes them, which is why so many gardeners let it stand guard as a trap crop. Knock the clusters off with a firm spray of water, let a few stay if the plant is quietly protecting your vegetables, and if one plant gets truly swamped you can simply pull it and wash the worst leaves with insecticidal soap.
Fix:
- Hose off colonies with a strong jet of water
- Tolerate moderate numbers when used intentionally as an aphid trap crop and remove the worst-infested plants
- Apply insecticidal soap to heavily infested foliage if needed
Ragged holes chewed through the leaves
Those tattered leaves usually come down to cabbageworms and cabbage loopers, the small green caterpillars of the cabbage white butterfly, and they are easy to handle once you know to look. Give the leaves a gentle check every few days and lift the caterpillars off by hand, since they blend right in and hide well. If you have planted near brassicas, the nasturtium is doing you a favor by drawing them in, and a little Bt will settle any heavy feeding.
Fix:
- Handpick caterpillars
- Use as a companion trap to draw cabbage pests away from nearby brassicas
- Apply Bacillus thuringiensis (Bt) to heavily fed foliage if needed
Plenty of leaves but hardly any flowers
Do not worry, this one is completely fixable and it simply means the soil is too rich for a plant that likes to stay a little hungry. When they are fed or set into fertile ground, nasturtiums answer with a mound of green and hold back their flowers. Ease off the fertilizer, move them to lean, well-drained soil in full sun, and the blooms will come along on their own.
Fix:
- Stop fertilizing
- Grow in lean, well-drained soil in full sun
Toxicity
Here is a reassuring note for homes with pets: nasturtium is safe all round. The ASPCA lists it as non-toxic to cats, dogs, and horses, and the leaves and flowers are edible for people, with a bright peppery flavor. There is nothing here you need to keep away from curious animals or children.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Rest easy with cats around this one, since the ASPCA rates garden nasturtium non-toxic to them and a curious taste will do no harm.
Dogs None
Dogs are perfectly fine here too. A chewed leaf or flower will not hurt them, though as with any plant a large mouthful might loosen the stomach a little.
Horses None
Horses can graze on nasturtium safely, since the ASPCA lists it as safe for them, so there is no cause for concern.
Rabbits Safe
The peppery leaves and flowers are gentle enough for rabbits, and many will nibble them happily as a fresh little treat.
Livestock Safe
Grazing animals can eat the foliage with no worry, so a plant growing within reach of the paddock is nothing to fret over.
Birds Safe
Backyard birds and chickens can peck at the leaves and seeds in comfort, with no toxic parts anywhere to steer them away from.
People Safe
You can enjoy the leaves and flowers yourself, since both are edible with a bright, peppery bite that shines in salads. The young seed pods are lovely pickled like capers, too.
Varieties
Nasturtiums come in trailing climbers and neat little bushy dwarfs, with flowers ranging from soft cream to deep scarlet, so there is a friendly one for every spot. These are the ones worth getting to know by name.
Alaska
A compact, bushy pick that people love as much for its cream-marbled variegated leaves as for the flowers themselves.
Empress of India
A tidy, compact plant whose deep crimson-scarlet flowers sit against striking dark blue-green leaves.
Jewel
A gentle mounding dwarf that offers semi-double to double flowers on neat, bushy little plants.
Climbing/Tall single
A spirited trailing or climbing form that stretches to around 10 feet (3 m) and loves a fence or trellis to hold.
Companions
Nasturtiums earn their place beside vegetables by drawing pests onto themselves and away from the crop, which makes them a useful neighbor for brassicas and squash alike.
Plant near
Cabbage and other brassicas: Used as a companion and trap crop; nasturtium helped reduce imported cabbageworm and cabbage looper damage in broccoli and cabbage.
Squash and other cucurbits: Interplanting nasturtium helped reduce squash bug and cucumber beetle damage in squash and pumpkin.
How to propagate
Nasturtiums are among the easiest plants to start from seed, and those big seeds and quick sprouting make them a truly reassuring choice for a first-time grower.
SeedEasy
Direct sow after the last spring frost once soil is warm. · Germinates in about 7 to 14 days; blooms within roughly 5 to 7 weeks.
If you are new to seeds, this is a wonderful place to begin, because the big, pea-sized seeds are forgiving and easy to handle. Soak them overnight so the coat softens, then tuck them right where you want the plants to stay once the spring frost has passed and the soil feels warm, since the roots dislike being disturbed and the plant rarely transplants well. Little seedlings push up in 7 to 14 days, and the first cheerful flowers arrive within about 5 to 7 weeks. Want a slight head start? Sow into biodegradable pots that go straight into the ground, roots and all.
Myths
Nasturtium is poisonous to cats and dogs.
You can relax on this one. The ASPCA lists garden nasturtium as non-toxic to cats, dogs, and horses, and the leaves and flowers are even good to eat for people. The worry traces back to watercress, a separate plant that carries the botanical name Nasturtium officinale and causes the confusion. Tropaeolum majus is safe to grow around pets.
Nasturtiums repel aphids and keep them out of the garden.
It works the other way around, and that is actually good news for you. A nasturtium draws aphids in rather than driving them off, which is the very reason it makes such a helpful trap crop. Set it near your vegetables and it gathers aphids and some caterpillars onto itself, keeping them off the plants you care about most.