Few plants give back as generously for as little effort as nasturtiums. Sow a handful of those big, wrinkled seeds in poor soil, give them sun, and within a couple of months you have a cascade of jewel-toned blooms, lily-pad leaves you can toss in a salad, and a living trap that pulls aphids off your vegetables. Nasturtiums (Tropaeolum) are one of the most forgiving annuals you can grow, which makes them perfect for beginners, kids, and anyone who wants a lot of color without a lot of fuss.
The catch, if there is one, is that nasturtiums reward neglect and punish pampering. Rich soil and a heavy hand with fertilizer give you a jungle of leaves and almost no flowers. Once you understand that one quirk, the rest of nasturtium care falls into place. Here is how to plant, grow, harvest, and troubleshoot them from seed to frost.
Nasturtiums at a glance
Nasturtiums are native to South America and belong to their own small plant family, Tropaeolaceae. The two species you are most likely to grow are Tropaeolum majus, the climbing and trailing type, and Tropaeolum minus, the compact bush and dwarf type. Both are grown as annuals in most of the country, though in frost-free regions they can behave as short-lived perennials.
The whole plant is edible, from the peppery leaves to the bright flowers to the green seedpods, which can be pickled like capers. The blooms come in far more than the classic orange and yellow, including cream, peach, salmon, deep red, burgundy, and bicolors, and some varieties carry attractively marbled or variegated foliage. Beyond looks, nasturtiums earn their keep in the vegetable garden as a companion plant, drawing pests away from crops and pulling in bees, hummingbirds, and hoverflies.
Choosing the right type of nasturtium
The first decision is growth habit, because it changes where the plant belongs.
- Trailing and climbing types (T. majus) send out long stems that scramble up to three feet or more. Train them up a trellis, obelisk, or fence, let them spill from a hanging basket or window box, or run them along the edge of a raised bed so they cascade over the side. Left in open ground, they make fast ground cover.
- Bush and dwarf types (T. minus) stay compact, often around 12 inches, and hold their shape without support. These are the ones for containers, the front of a border, and tidy edging.
A few varieties worth seeking out: ‘Empress of India’ has crimson flowers against dark blue-green leaves; ‘Alaska’ series carries cream-and-green marbled foliage; ‘Peach Melba’ offers soft creamy blooms with orange-red centers; ‘Black Velvet’ is a near-black deep red; and ‘Jewel Mix’ is a reliable all-rounder for cascading color. For containers, lean toward the compact named varieties so the plant does not swamp its pot.
Where to plant nasturtiums
Give nasturtiums as much sun as you can. They will survive in partial shade, but a shaded plant puts out leaves and few flowers, so that placement only makes sense if you are growing strictly for edible greens. For the best bloom, choose a spot with at least six hours of direct sun a day.
Soil is where most people go wrong. Nasturtiums flower best in lean, well-drained soil that you have not improved. Fertile ground and added fertilizer push the plant into leafy growth, with any flowers that do appear hidden under the foliage. Skip the compost-rich beds you reserve for hungry vegetables and plant nasturtiums in your poorest, fastest-draining ground instead. Good drainage matters more than fertility, since these plants resent sitting in wet soil.
Around the vegetable garden, place nasturtiums along the borders of beds growing crops that aphids and flea beetles love, such as lettuce, kale, beans, cabbage, broccoli, and cucumber. They will take the hit so your produce does not.
How to grow nasturtiums from seed
Nasturtiums have fragile, sensitive roots and resent being moved, so the simplest and most reliable approach is to sow the seeds directly where they will grow. Wait until all danger of frost has passed and the soil has warmed to roughly 55 to 65 degrees Fahrenheit, usually one to two weeks after your last spring frost.
Those big seeds have a tough coat, and you can speed up germination with a little prep:
- Scarify (optional): Rub the seed coat lightly with a nail file or sandpaper, or nick it with a knife, just until the lighter inner layer shows. You do not need to expose the whole seed.
- Soak: Drop the seeds in lukewarm water for 8 to 24 hours, until they swell. This alone can cut germination time noticeably.
- Sow: Plant seeds about half an inch deep, spacing them 10 to 12 inches apart in beds. In containers you can sow a little tighter, around 4 to 6 inches apart, and thin later. Cover, firm gently, and keep the soil evenly moist.
Seedlings usually emerge in 7 to 14 days. Once they are up and growing, thin bed-sown plants to about 10 to 12 inches apart so each has room.
If you must start seeds early indoors, use peat pots or root trainers that go straight into the ground, planting the whole pot to avoid disturbing the roots. Start them only 4 to 6 weeks before your last frost date, since they grow fast and dislike being potbound.
Growing nasturtiums in containers and hanging baskets
Nasturtiums are made for pots. Choose a container with good drainage holes and fill it with a light, free-draining mix; cutting your potting soil with up to a third grit, perlite, or fine gravel keeps fertility low and water moving. Place the pot somewhere it gets full sun, and plant compact or trailing varieties so the display stays in scale.
The one place container growing differs from the in-ground rule is feeding. Potted nasturtiums have only the nutrients in their small volume of mix, and over a long season that can run out, showing up as pale, leggy growth. If a container plant looks starved rather than simply leafy, a single light dose of balanced fertilizer can revive it. In open ground, you should almost never need to feed at all.
How to care for nasturtiums
Day to day, nasturtium care is close to nothing, which is exactly the point.
Watering. Plants in the ground are fairly drought tolerant once established and rarely need watering except in a long dry spell. Water deeply but infrequently, letting the top inch or two of soil dry between waterings, because soggy roots quickly rot. Container plants dry out much faster, so check them often and keep the mix evenly moist but never waterlogged. As a bonus, those round leaves are water-repellent, which helps the plant shrug off leaf diseases even when the foliage gets wet.
Feeding. As a rule, do not feed in-ground nasturtiums at all. Lean soil is what gives you flowers. Save the light-feeding exception for starved container plants, as noted above.
Deadheading. Nasturtiums will bloom continuously on their own, but pinching off spent flowers redirects energy from seed-making back into new blooms and extends the show. It also keeps the plant from self-sowing where you do not want it.
Pinching and pruning. If trailing varieties get long and bare in the middle, cut the leggy vines back by 6 to 8 inches to push out fresh side branches and more buds. Trim any stems that are crowding neighboring plants back at the base.
Harvesting and eating nasturtiums
Every part of a nasturtium is edible, with a peppery, watercress-like bite that comes from the same family of mustard-oil compounds. Always grow plants you intend to eat without pesticides, even organic ones.
- Leaves can be picked as soon as they are big enough to use. Snip individual leaves with clean scissors and never take more than about a third of the plant at once. Younger leaves are tender and milder; older ones turn sharp.
- Flowers are best harvested just after they open, in the morning, when their flavor is at its mildest and sweetest. The blooms are gentler than the leaves, which makes them a good edible garnish for salads, cakes, cheese boards, and even frozen into ice cubes.
- Seedpods can be picked while green and immature, then pickled in vinegar as a homegrown substitute for capers, the so-called “poor man’s capers.”
You can also steep flowers in white wine vinegar for a couple of weeks to make a colorful, peppery dressing base.
Saving seed and self-sowing
Nasturtiums reseed themselves enthusiastically. Round green seeds form in clusters of three at the base of each fading flower, and if left alone they drop and often sprout the following spring. To save seed deliberately, stop deadheading in late summer or early fall and let the pods mature. For the best germination later, gather the seeds once they are large; size is a better maturity signal than color, since many ripen while still green and blend into the foliage. Bring them indoors, let them dry completely in a cool, dark place, and store them in a paper envelope until next season.
If volunteer seedlings show up where you do not want them, they pull out easily by hand.
Are nasturtiums annual or perennial?
It depends on your climate. In USDA zones 9 through 11, where frost is rare or absent, nasturtiums can persist as short-lived perennials and may bloom on and off for much of the year, though they often pause during the hottest, most humid stretch of summer. In zone 8 and colder, frost kills them, so they are grown as annuals and resown each spring.
Gardeners in cold climates who want to keep a favorite plant going can lift it before the first hard frost: cut the stems and leaves back to about 10 to 12 inches, dig up the plant with its root ball, and pot it into a container at least 10 inches across to overwinter on a bright, cool windowsill. In most cases, though, it is easier to let the plant set seed and start fresh in spring.
Common nasturtium problems and how to fix them
Nasturtiums are tough, but a few issues come up often enough to recognize on sight.
Lots of leaves, few flowers. This is the classic nasturtium complaint, and it almost always traces back to soil that is too rich or too much fertilizer. Resist the urge to feed; cutting nutrients usually brings the blooms back. Too little sun causes the same thing, so make sure the plant gets its six-plus hours.
Yellowing leaves. Yellow foliage is the plant telling you a growing condition is off. The usual suspects are overwatering or poor drainage, too little water, too much fertilizer, not enough light, or a pest infestation. Work through those one at a time before assuming disease. Stray herbicide overspray can also yellow the leaves.
Leggy, sparse growth. Trailing types in particular get leggy when they are short on light. Move container plants to a sunnier spot and prune the long vines back 6 to 8 inches to force bushier growth.
Aphids and blackfly. Nasturtiums are a magnet for aphids, which is partly the point as a trap crop, but a heavy load on plants you are growing for flowers or food is unwelcome. Blast them off with a jet of water, encourage ladybugs, lacewings, and hoverflies that eat them, or treat with insecticidal soap or neem oil if needed.
Cabbage white caterpillars. Large and small white butterflies lay greenish eggs on the leaf undersides, and the hatching caterpillars chew holes in the foliage. This is useful when the goal is to lure them away from your brassicas, but a problem on ornamental plants. Inspect regularly and squash the eggs and young caterpillars by hand, or relocate them to plants you do not mind sacrificing.
Whiteflies. These tiny insects feed on the undersides of the leaves and can discolor and weaken the plant. Treat the same way you would aphids, with water sprays, beneficial insects, insecticidal soap, or neem oil.
Mosaic virus. Light-and-dark green mottling on the leaves and malformed, splotchy flowers point to mosaic virus, which is spread by aphids and leafhoppers. There is no cure; remove and dispose of infected plants, control sap-sucking pests, and clean up plant debris at the end of the season, since the virus can overwinter on it.
Bacterial wilt. Sudden yellowing and wilting, black streaks in the stems, and a milky ooze from cut stem ends signal bacterial wilt. Infected plants often die before flowering and cannot be saved; pull and discard them and avoid replanting in the same spot.
Avoid reaching for chemical pesticides on plants you plan to eat, and remember that a healthy nasturtium tolerates a fair amount of pest pressure on its own.
Plant nasturtiums once and you will likely keep finding room for them, between the edible leaves, the steady flowers, the pollinators they pull in, and the pests they pull away from everything else. Tuck a few seeds along a sunny edge or a raised-bed border this season, hold back on the fertilizer, and let this cheerful, hardworking annual do the rest.