Ornamental · Tropaeolaceae
Nasturtium
Tropaeolum majus
Give it poor soil and full sun, and the nasturtium returns peppery leaves and bright, edible flowers across the whole summer.
Full sun
50–86°F · 10–30°C
35–50 days
USDA 2–11
Overview
Nasturtium brings a relaxed, cottage-garden ease to a summer plot, a fast annual grown for both its edible flowers and peppery leaves. It climbs a trellis, spills over the edge of a raised bed, or settles into a tidy mound near the path, so it slots into a border, a container by the door, or a kitchen garden with equal grace. That warm-toned color and the fresh, watercress-like bite carry it from the bed straight to the summer table.
Its charm lies in how undemanding it is, which suits a garden meant to be lived in rather than fussed over. Where most plants ask for feeding and rich ground, a nasturtium looks its best in lean, poor soil left plain. Overtend it and the display slips into leaf, so the elegant move is to plant it and let it be.
It also pulls its weight in the wider scheme of the plot. Aphids and cabbage caterpillars are drawn to it, a habit gardeners use to their advantage by planting it as a trap crop that keeps those pests off the vegetables growing alongside.
Care
The short version: full sun and lean, well-drained soil with no fertilizer. Water enough to settle young plants, then let established ones dry a little between drinks, and sow the seeds right where they will grow rather than moving them later.
Light
Nasturtiums flower most freely in full sun, so the brightest corner of the plot is where they shine. They will grow in part shade, but the trade is more leaf and less color, which rather defeats the point.
Water
Keep the soil lightly and evenly moist while young plants settle into their spot. Once established in lean, well-drained ground, they take short dry spells in stride, so let the top inch dry before the next drink. Waterlogged soil is the one thing that spoils the effect.
Soil
This is a plant that looks its best on a plain diet. Set it in lean, well-drained loam or sandy soil of poor to average fertility and hold back the rich compost. Fertile ground trades the flowers you want for foliage you did not ask for.
Temperature
Nasturtiums are content between 50°F and 86°F (10°C to 30°C), an easy range across most summer gardens. They are tender annuals with no frost tolerance, so wait out the cold before sowing and expect the show to close at the first hard frost.
Humidity
Ordinary outdoor air suits them, with no figure to fuss over. Good airflow does more for them than any moisture in the air, since crowding invites the aphids the plant already attracts.
Feeding
Leave the feeding out of the routine entirely. Nasturtiums bloom best in hungry soil, and any nitrogen-rich fertilizer leaves a leafy plant with almost nothing to show.
Pruning
The upkeep begins and ends with deadheading. Pinch off spent flowers to keep fresh ones coming, and clear away any damaged or diseased growth as it appears.
Size & spacing
Plants range from 12 inches (30 cm) on the bushy dwarfs to 10 feet (3 m) on the climbers, so the form decides where it belongs. Give trailing types room to spill and offer the tall ones a support to rise against.
When to plant
Nasturtiums move fast and hold no patience for frost, so the season sets the rhythm. Sow the seeds into warm soil once the spring frost has passed, and the color runs from early summer through 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
Trouble with nasturtiums tends to arrive as pests on the leaves or a plant that grows lush yet withholds its color. Most of it reads at a glance and settles just as easily. Match what you see below, then step in before it takes hold.
Sticky leaves and crowds of tiny insects on the shoot tips
A rush of aphids on the shoot tips is less a crisis than a sign the plant is playing the role it was placed for, since almost nothing gathers them like a nasturtium, and that talent is what makes it such a valued trap crop out in the beds. A firm jet of water clears the colonies, and a few can be left to their business while the plant quietly draws pests away from the vegetables nearby. When a plant is truly overrun, lift it out 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
Ragged, chewed foliage points to cabbageworms and cabbage loopers, the green caterpillars that come from the cabbage white butterfly. They tuck themselves against the leaves and go unnoticed, so a regular look-over and a hand-pick keeps them in check. Set near brassicas, a nasturtium gathers these pests onto itself, and a little Bt settles any serious 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
A leafy plant that never quite delivers its color usually means the soil is too rich. Nasturtiums put on their show when kept a little hungry, so feeding them or planting into fertile ground trades the flowers for a mound of green. Set the fertilizer aside and give them lean, well-drained soil in full sun, and the blooms return.
Fix:
- Stop fertilizing
- Grow in lean, well-drained soil in full sun
Toxicity
A welcome note for a lived-in home: 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. Nothing here needs to be kept out of reach of curious pets or children.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
A cat drifting past the pots is in no danger, since the ASPCA rates garden nasturtium non-toxic to them and a stray nibble means nothing.
Dogs None
Dogs share the space safely as well. A chewed leaf or flower will not harm them, though a large helping of any plant can unsettle the stomach.
Horses None
Horses can graze the foliage with ease, since the ASPCA counts nasturtium among the plants safe for them.
Rabbits Safe
The peppery leaves and flowers suit rabbits perfectly well, and many will browse them as a fresh little indulgence.
Livestock Safe
Grazing animals take the foliage without harm, so a planting near the paddock sits easily in the landscape.
Birds Safe
Garden birds and chickens can peck the leaves and seeds in comfort, with no toxic parts anywhere among them.
People Safe
The leaves and flowers come straight to the table, bringing a bright, peppery bite that dresses a salad beautifully. Even the young seed pods have a place, pickled much like capers.
Varieties
Nasturtiums arrive as trailing climbers and neat bushy dwarfs, with color ranging from soft cream to deep scarlet, so there is a form to suit any corner. These are the ones worth knowing by name.
Alaska
A compact, bushy type prized as much for its cream-marbled variegated leaves as for the flowers they frame.
Empress of India
A compact plant that sets deep crimson-scarlet flowers against dark blue-green leaves for a rich, moody pairing.
Jewel
A mounding dwarf that carries semi-double to double flowers on neat, well-behaved plants.
Climbing/Tall single
A vigorous trailing or climbing form that reaches about 10 feet (3 m), tailor-made for dressing a fence or trellis.
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 raise from seed, and those big seeds and quick germination make them a graceful first project for a new 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.
Few plants make raising a summer display so effortless, thanks to seeds that are big, pea-sized, and forgiving to handle. Soak them overnight to soften the coat, then settle them right where they are meant to stay once the spring frost has passed and the soil has warmed, since the plant resents having its roots moved and rarely transplants well. Seedlings surface in 7 to 14 days, and the first color arrives within about 5 to 7 weeks. For an early start, sow into biodegradable pots that slip straight into the ground.
Myths
Nasturtium is poisonous to cats and dogs.
There is nothing here to keep from the household. The ASPCA lists garden nasturtium as non-toxic to cats, dogs, and horses, and the leaves and flowers are welcome on the plate for people too. The old worry belongs to watercress, an unrelated plant that carries the botanical name Nasturtium officinale. Tropaeolum majus is safe to grow around pets.
Nasturtiums repel aphids and keep them out of the garden.
The truth runs the other way. A nasturtium attracts aphids rather than repelling them, and that is precisely the appeal of using it as a trap crop. Placed among the vegetables, it collects aphids and a few caterpillars onto itself and keeps them off the plants meant for the table.