Ornamental · Tropaeolaceae
Nasturtium
Tropaeolum majus
Give it poor soil and full sun, and the nasturtium pays you back 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 that's grown for both its edible flowers and peppery leaves. Depending on the type, it'll climb, trail, or mound, and those round leaves and warm-toned blooms have kept it a cottage-garden favorite for ages. The whole plant has a fresh, watercress-like bite, which is why it turns up in salads and as a garnish on the plate.
Here's the fun part: it barely asks for anything. 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 hardly a flower, so really the trick is to plant it and step back.
And it earns its keep beyond just looking nice. Aphids and cabbage caterpillars can't resist it, which gardeners turn into a win by growing it as a trap crop that 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 going, then let established ones dry out a little between drinks, and sow the seeds right where they'll grow instead of transplanting.
Light
Nasturtiums want full sun if you want the most flowers. They'll still grow in part shade, but you'll trade blooms for leaves, so give them the sunniest spot you've got.
Water
Keep the soil lightly and evenly moist while the young plants are finding their feet. Once they're settled in lean, well-drained ground, they shrug off short dry spells just fine, so let the top inch dry before you water again. The one thing to avoid? Waterlogged soil.
Soil
This is a plant that actually thrives on being ignored. Give it lean, well-drained loam or sandy soil that's poor to average in fertility, and skip the rich compost. Fertile ground is the surest way to end up with leaves instead of flowers.
Temperature
Nasturtiums are happy 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 you sow, and expect them to call it quits at the first hard frost.
Humidity
Regular outdoor humidity suits them fine, so there's no number to chase. What matters more is good airflow, since crowded plants just invite the aphids this one already draws in.
Feeding
Don't feed them, simple as that. Nasturtiums flower best in hungry soil, and any nitrogen-rich fertilizer leaves you with a leafy plant and barely any blooms.
Pruning
There's not much to do beyond a little deadheading. Pinch off the spent flowers to keep new ones coming, and clear away any damaged or diseased growth when you spot 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 plant. Give the trailing forms room to wander, and hand the tall ones something to grab onto.
When to plant
Nasturtiums grow fast, and they won't take frost, so timing's easy. Sow the seeds straight into warm soil once the spring frost has passed, and they'll bloom from early summer right up until the first fall frost wraps things up.
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
With nasturtiums, trouble usually shows up as pests on the leaves or a plant that grows lush but won't flower. The good news? Most of it's easy to read and easy to fix. Just match what you see below, then act before it spreads.
Sticky leaves and crowds of tiny insects on the shoot tips
Spot a crowd of aphids on the shoot tips? That's honestly the plant working as intended, since almost nothing pulls aphids in like a nasturtium, and that's why so many gardeners keep it around as a trap crop. Just knock the colonies off with a strong spray of water, and don't sweat a few stragglers if the plant's busy luring pests off your vegetables. When one plant gets truly swamped, pull it and wipe down 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 chewed-up leaves are usually the work of cabbageworms and cabbage loopers, the little green caterpillars that hatch from cabbage white butterflies. They blend right into the foliage, so check the leaves often and just pick them off by hand. If there are brassicas nearby, the nasturtium's actually pulling these pests onto itself, and a bit of Bt takes care of 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
Lots of leaves and hardly a flower? That's the classic tell that the soil is too rich. Nasturtiums bloom best when they're a bit hungry, so feeding them or planting them in fertile ground just gives you a pile of leaves. Ease off the fertilizer and grow them in lean, well-drained soil in full sun, and the flowers show up.
Fix:
- Stop fertilizing
- Grow in lean, well-drained soil in full sun
Toxicity
Good news if you've got 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. So there's nothing here you need to keep away from curious animals or kids.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Cats are totally fine around it, since the ASPCA rates garden nasturtium non-toxic to them, so a curious nibble is no big deal.
Dogs None
Dogs are all clear here too. A chewed leaf or flower won't hurt them, though you know how it goes, a big mouthful of any plant can upset the stomach.
Horses None
Horses can graze on it no problem, since the ASPCA says it's safe for them.
Rabbits Safe
The peppery leaves and flowers are fine for rabbits, and plenty of them will happily munch on them as a fresh treat.
Livestock Safe
Grazing animals can eat the foliage without any harm, so a plant near the paddock isn't anything to worry about.
Birds Safe
Backyard birds and chickens can peck at the leaves and seeds safely, since there aren't any toxic bits to steer clear of.
People Safe
You can eat the leaves and flowers yourself, and they've got a bright, peppery bite that's great in salads. The young seed pods? You can pickle those like capers.
Varieties
Nasturtiums come as trailing climbers and tidy bushy dwarfs, with flowers that run from soft cream to deep scarlet. Here are the ones worth knowing by name.
Alaska
It's a compact, bushy type that people grow just as much for its cream-marbled variegated leaves as for the flowers.
Empress of India
It's a compact plant that sets deep crimson-scarlet flowers against really striking dark blue-green leaves.
Jewel
It's a mounding dwarf that carries semi-double to double flowers on neat, bushy little plants.
Climbing/Tall single
It's a vigorous trailing or climbing form that runs to about 10 feet (3 m), so it's 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 about as easy as it gets to start from seed, and those big seeds and quick germination make them a great pick 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.
Growing them from seed couldn't be much easier, since the seeds are big, pea-sized, and simple to handle. Soak them overnight to soften the coat, then just sow them right where you want them once the spring frost's passed and the soil's warmed up, because this plant hates having its roots messed with and rarely transplants well. You'll see seedlings pop up in 7 to 14 days, and the first flowers within about 5 to 7 weeks. Want a head start? Sow into biodegradable pots and pop the whole thing in the ground.
Myths
Nasturtium is poisonous to cats and dogs.
Not true, so there's no need to worry. The ASPCA lists garden nasturtium as non-toxic to cats, dogs, and horses, and the leaves and flowers are even edible for people. So where did the scare come from? Watercress, a totally different plant that just happens to carry the botanical name Nasturtium officinale. Tropaeolum majus is safe to grow around pets.
Nasturtiums repel aphids and keep them out of the garden.
It's actually the opposite. A nasturtium attracts aphids rather than repelling them, and that's the whole reason it works as a trap crop. Plant it near your vegetables and it pulls aphids and some caterpillars onto itself, keeping them off the plants you're trying to protect.