Ornamental · Tropaeolaceae
Nasturtium
Tropaeolum majus
Give it poor soil and full sun, and the nasturtium repays you with peppery leaves and bright, edible flowers all summer.
Full sun
50–86°F · 10–30°C
35–50 days
USDA 2–11
Overview
Nasturtium is a fast, cheerful annual grown for both its edible flowers and peppery leaves. It climbs, trails, or mounds depending on the type, and the round leaves and warm-toned blooms have made it a cottage-garden favorite for generations. The whole plant carries a fresh, watercress-like bite that turns up in salads and on the plate as a garnish.
What sets it apart is how little it asks. Most plants want feeding and rich ground, but a nasturtium does its best work in lean, poor soil with nothing added. Spoil it and you get a tangle of leaves and barely a flower, so the trick is to plant it and step back.
It also earns its keep beyond looks. Aphids and cabbage caterpillars find it irresistible, which gardeners turn to their advantage by planting it as a trap crop that pulls those pests off nearby vegetables.
Care
The short version: full sun and lean, well-drained soil with no fertilizer. Water enough to keep young plants going, then let established plants dry a little between drinks, and direct sow the seeds where they'll grow rather than transplanting.
Light
Nasturtiums want full sun to flower at their best. They'll grow in part shade, but you'll trade blooms for leaves, so give them the sunniest spot you have.
Water
Keep the soil lightly and evenly moist while young plants find their feet. Once established in lean, well-drained ground, they shrug off short dry spells, so let the top inch dry before watering again. The one thing to avoid is waterlogged soil.
Soil
This is a plant that thrives on neglect. Give it lean, well-drained loam or sandy soil of poor to average fertility, and skip the rich compost. Fertile ground is the surest way to get leaves instead of flowers.
Temperature
Nasturtiums grow happily between 50°F and 86°F (10°C to 30°C). They're tender annuals with no frost tolerance, so wait for the cold to pass before sowing and expect them to finish at the first hard frost.
Humidity
Ordinary outdoor humidity suits them fine, with no number to chase. Good airflow matters more than moisture in the air, since crowded plants invite the aphids this plant already attracts.
Feeding
Don't feed them. Nasturtiums flower best in hungry soil, and any nitrogen-rich fertilizer gives you a leafy plant with almost no blooms.
Pruning
There's little to do beyond deadheading. Pinch off spent flowers to keep new ones coming, and clear away any damaged or diseased growth as you spot it.
Size & spacing
Plants range from 12 inches (30 cm) on the bushy dwarfs to 10 feet (3 m) on the climbers, so check the type before you place them. Give trailing forms room to roam and a support for the tall ones to grab.
When to plant
Nasturtiums grow fast and won't tolerate frost. Sow the seeds straight into warm soil once the spring frost has passed, and the plants bloom from early summer right up until the first fall frost closes the season.
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
Nasturtium trouble tends to show up as pests on the leaves or a plant that grows lush but won't flower. Most of it is easy to read and easy to fix. Match what you see below, then act before it spreads.
Sticky leaves and crowds of tiny insects on the shoot tips
Nasturtiums pull in aphids like almost nothing else in the garden, which is exactly why so many people grow them as a trap crop. Blast the colonies off with a strong jet of water and tolerate a few if the plant is doing its job of luring pests away from your vegetables. When a plant is overrun, pull it and treat the worst foliage 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
The culprits are usually cabbageworms and cabbage loopers, the green caterpillars of the cabbage white butterfly. Pick them off by hand and check the leaves often, since they hide well against the foliage. Planted near brassicas, a nasturtium draws these pests onto itself, and a dose of Bt clears up 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
This is the classic sign of soil that is too rich. Nasturtiums bloom best when they are a little hungry, so feeding them or planting in fertile ground gives you a mound of leaves and few blooms. Stop fertilizing and grow them in lean, well-drained soil in full sun, and the flowers follow.
Fix:
- Stop fertilizing
- Grow in lean, well-drained soil in full sun
Toxicity
Good news for households 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's nothing here you need to keep away from curious animals or children.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
The ASPCA lists garden nasturtium as non-toxic to cats, so a curious nibble is nothing to worry about.
Dogs None
Dogs are in the clear here too. A dog that chews a leaf or flower won't be harmed, though a big mouthful of any plant can loosen the stomach.
Horses None
Horses can graze nasturtium without trouble, since the ASPCA rates it safe for them.
Rabbits Safe
The peppery leaves and flowers are fine for rabbits to eat, and many will happily browse them as a fresh treat.
Livestock Safe
Grazing animals can eat the foliage without harm, so a plant within reach of the paddock poses no danger.
Birds Safe
Backyard birds and chickens can peck at the leaves and seeds safely, with no toxic parts to avoid.
People Safe
Both the leaves and flowers are edible, with a bright, peppery bite that's a favorite in salads. The young seed pods can even be pickled like capers.
Varieties
Nasturtiums come in trailing climbers and tidy bushy dwarfs, with flowers from soft cream to deep scarlet. These are the ones worth knowing by name.
Alaska
A compact, bushy type grown as much for its cream-marbled variegated leaves as for its flowers.
Empress of India
A compact plant that pairs deep crimson-scarlet flowers with striking dark blue-green leaves.
Jewel
A mounding dwarf that carries semi-double to double flowers on tidy, bushy plants.
Climbing/Tall single
A vigorous trailing or climbing form that reaches about 10 feet (3 m), made for fences and trellises.
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 the big seeds and quick germination make them a fine 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.
Nasturtiums grow easily from their big, pea-sized seeds. Soak them overnight to soften the coat, then sow them right where they'll grow once the spring frost has passed and the soil has warmed, since the plant hates having its roots disturbed and rarely transplants well. Seedlings break ground in 7 to 14 days, and you'll see the first flowers within about 5 to 7 weeks. If you want a head start, sow into biodegradable pots that go straight into the ground.
Myths
Nasturtium is poisonous to cats and dogs.
The ASPCA lists garden nasturtium as non-toxic to cats, dogs, and horses, and its leaves and flowers are even edible for people. The mix-up comes from watercress, a completely different plant whose botanical name happens to be Nasturtium officinale. Tropaeolum majus is safe to grow around pets.
Nasturtiums repel aphids and keep them out of the garden.
They do the opposite. A nasturtium attracts aphids rather than repelling them, which is the whole point of using it as a trap crop. Planted near your vegetables, it draws aphids and some caterpillars onto itself and away from the plants you want to protect.