Guide to Growing Nasturtiums Successfully

Introduction to Nasturtiums: A Gardener’s Delight

If you’re looking for a flower that’s genuinely hard to go wrong with, nasturtiums are probably it. Whether you’ve been gardening for decades or you’ve just bought your first trowel, these cheerful, bright blooms — technically known as Tropaeolum — have a way of making every gardener look good. They come in fiery shades of orange, red, yellow, and cream, and because they grow so quickly, you won’t be waiting long before your garden starts looking like you actually know what you’re doing.

What really sets nasturtiums apart is how flexible they are. They’ll grow happily in a pot on your balcony, spill over the sides of a raised bed, climb a trellis if you give them one, or just spread themselves across the ground in a low, colourful mound. And unlike a lot of ornamental plants, these ones actually pull double duty — the flowers and leaves are edible, with a peppery kick that works brilliantly in salads. Getting to know what nasturtiums actually need is the first step toward making the most of them.

There’s an ecological side to them too, which is easy to overlook. Bees, hoverflies, and butterflies are all drawn to those trumpet-shaped blooms, making nasturtiums a genuinely useful plant for pollinators. They also do something clever in the vegetable garden: aphids love them, which means pests that might otherwise go for your beans or roses end up on the nasturtiums instead. It’s a trick gardeners call trap cropping, and it works surprisingly well. So really, you’re getting a beautiful plant, a salad ingredient, and a pest management tool all in one go.

Choosing the Right Variety for Your Garden

There are more nasturtium varieties out there than most people realize, and picking the right one for your space makes a real difference. Growth habit is the main thing to think about: you’ve got compact dwarf types, long trailing or climbing types, and semi-trailing varieties that sit somewhere in between. If you’re working with a small patio pot or a window box, a dwarf variety like ‘Tom Thumb’ is perfect — it stays around 30 centimeters tall and keeps things looking tidy without taking over.

If you’ve got more room to play with, the climbing and trailing varieties are fantastic. ‘Tall Mixed’ and ‘Spitfire’ can easily reach a meter or more, scrambling up bamboo canes, tumbling out of hanging baskets, or wandering across a slope or fence in the most satisfying way. They’ve got a relaxed, slightly wild look that fits right in with cottage gardens or any kind of informal planting. And because they flower for such a long stretch of the season, they’re brilliant for filling gaps.

If eating your nasturtiums is part of the appeal — and honestly, it should be — it’s worth choosing a variety with that in mind. ‘Alaska’ is a popular one, with its pretty green-and-cream variegated leaves and a flavour that’s somewhere between watercress and rocket. ‘Jewel of Africa’ is another great option, giving you vivid flowers and ornate foliage at the same time. Knowing what you want before you buy saves a lot of second-guessing when you’re standing in front of a seed rack.

• Dwarf/Bush varieties: ‘Tom Thumb’, ‘Whirlybird’, ‘Empress of India’ — ideal for containers and compact spaces
• Trailing/Climbing varieties: ‘Tall Mixed’, ‘Spitfire’, ‘Jewel of Africa’ — perfect for trellises, hanging baskets, and banks
• Variegated foliage varieties: ‘Alaska’ — attractive leaves and excellent culinary flavor
• Double-flowered varieties: ‘Peach Melba’, ‘Strawberries and Cream’ — unusual blooms with a more ornate appearance

When and How to Sow Nasturtium Seeds

Nasturtiums really prefer to be sown straight into the ground where they’re going to grow. Their roots don’t take kindly to being moved, so starting them in trays and transplanting later often results in a sulky plant that takes ages to recover. The ideal time to sow directly outdoors is once the last frost has passed and the soil is starting to feel a bit warmer underfoot — usually somewhere between mid-April and early June in temperate climates, though it’s always worth checking your local frost dates to be sure.

The good news is that nasturtium seeds are big, chunky, and easy to handle, which makes them one of the best seeds for kids and beginner gardeners to start with. Push each seed about two centimeters into the soil or compost, space them 25 to 30 centimeters apart, water gently, and then just leave them to it. They typically sprout within a week or two, and once they’re up, they really do get going fast. If you’d like a bit of a head start, you can sow them indoors three to four weeks before the last frost — but use small biodegradable pots so you can plant the whole thing out without touching the roots.

Here’s a sowing tip that catches a lot of gardeners off guard: don’t enrich your soil before planting nasturtiums. These plants come from South America, where they evolved in lean, well-drained soils, and when you give them rich, well-fed ground they respond by throwing out masses of lush leaves at the expense of flowers. It feels counterintuitive, but keeping the soil on the poorer side is actually one of the best things you can do for a big floral display. This is one of those cases where doing less genuinely gets you more.

Sunlight, Soil, and Watering Requirements

Nasturtiums are sun-seekers, and they’ll flower best with at least six hours of direct sunlight a day. A south or west-facing spot is ideal, especially if you’re gardening somewhere with cool summers — the extra warmth really helps. In hotter climates, a little afternoon shade is actually welcome, since intense heat can temporarily put the plants off flowering. Don’t worry too much if this happens; once things cool down toward late summer, they tend to bounce back and start blooming again with renewed enthusiasm.

In terms of soil, nasturtiums are refreshingly easy-going. Sandy, free-draining soil is fine, and so is moderately heavy soil, as long as it doesn’t stay waterlogged. They’re not bothered by pH either, tolerating conditions from mildly acidic to slightly alkaline without complaint. The one non-negotiable is drainage — sitting in wet soil for too long will rot their roots. If you’re dealing with heavy clay, raise the game a little by growing in raised beds or containers with some horticultural grit mixed into the compost.

When it comes to watering, the golden rule with nasturtiums is restraint. Once they’re established, they’re impressively drought-tolerant and usually only need watering once or twice a week in dry spells. Overwatering is actually one of the most common mistakes people make, and it shows up as yellowing leaves and fewer flowers. A simple way to judge it: let the top few centimeters of soil dry out before you water again. Container plants will dry out faster and need more attention, but the same principle applies — keep them from sitting in water and they’ll be much happier.

Common Pests, Problems, and How to Manage Them

There’s a slightly ironic side to growing nasturtiums as a trap crop: because they’re so good at attracting aphids away from other plants, you will almost definitely find colonies of blackfly on yours. It can look alarming when you first spot a cluster of them on the stems or under the leaves, but this is actually the nasturtium doing exactly what it’s supposed to do. The easiest way to deal with them is a firm jet of water from the hose, knocking them off and repeating whenever they reappear. It’s not glamorous pest control, but it works.

Caterpillars from the large white butterfly (Pieris brassicae) are another frequent visitor, and they can munch through leaves pretty quickly if they get established. Getting into the habit of checking the undersides of leaves for the yellow egg clusters is the most effective way to stay ahead of them. If you do find caterpillars, just pick them off by hand and move them well away from the garden — no chemicals needed. Bringing in natural predators like birds and ground beetles over time helps keep populations manageable on a longer-term basis too.

Powdery mildew can show up in humid conditions or where plants are packed in too closely together, appearing as a white, dusty coating on leaves and stems. It won’t usually kill a nasturtium outright, but it does slow things down and cut back on flowering. The best prevention is good spacing and avoiding watering over the top of the plants late in the day. If mildew does appear, strip off the affected leaves and improve the airflow around the plant. A diluted baking soda solution sprayed onto the leaves can help in more stubborn cases.

• Blackfly aphids: dislodge with water jets; encourage beneficial insects such as ladybirds and lacewings
• Caterpillars: check undersides of leaves regularly; hand-pick eggs and larvae; encourage bird activity
• Powdery mildew: improve airflow; avoid overhead watering; remove affected foliage promptly
• Slugs and snails: use copper tape around containers; apply grit mulch at soil level; set beer traps

Harvesting, Culinary Uses, and Seed Saving

One of the most genuinely enjoyable things about nasturtiums is that you can eat almost the whole plant. The flowers get the most attention, and deservedly so — they have a bright, peppery flavour that’s a little like watercress, which makes them brilliant scattered over salads, floated in soups, or perched on canapés. Pick them in the morning when they’re at their freshest, right after they’ve fully opened, and use them the same day if you can. They do wilt fairly quickly once cut, so they’re not great for storing.

The leaves are just as useful in the kitchen, especially the younger, smaller ones which have the best flavour without getting tough and fibrous. You can shred them into a green salad, blitz them into a peppery pesto with garlic, pine nuts, and olive oil, or use them as a wrap the way you might use a lettuce leaf. And if you want to try something a bit more unusual, the small green seeds — harvested while they’re still firm before they dry out and brown — can be pickled in vinegar with salt, sugar, and spices. The result is surprisingly similar to capers and genuinely delicious with cheese, cold meats, and fish.

Saving seed from nasturtiums is one of the more satisfying things you can do at the end of the gardening season. Let a few flowers go to seed, keeping an eye out for the distinctive round, wrinkled seeds that form at the base of spent blooms. When they’ve turned cream or pale brown and feel firm to the touch, harvest them and spread them out somewhere warm and airy to dry for a week or two. Pop them into a paper envelope, store it somewhere cool and dry, and they’ll stay viable for two or three years. It’s a completely free seed bank that builds itself a little more each year.

Extending the Season and Caring for Plants Long-Term

In most temperate gardens, nasturtiums are grown as annuals — they do their thing over a single season and then that’s it. In frost-free climates or under glass, some varieties can keep going year after year, but for most of us, the best way to stretch the season is through successional sowing. If you make small additional sowings every three to four weeks from spring through early summer, you’ll end up with plants at different stages throughout the season, so when your first batch starts to wind down in late summer, newer plants are just hitting their stride.

Deadheading throughout the season is well worth the small effort it takes. When you remove spent flower heads regularly, the plant puts its energy into making more flowers rather than setting seed and calling it a day. Just pinch off the faded blooms with your fingers or a small pair of scissors, taking care not to damage the stems around them. If you want to save seed from particular plants — maybe one with an especially good colour or lots of vigour — mark those plants early in the season, let them seed without deadheading, and carry on deadheading everything else as normal.

As autumn arrives and temperatures drop, nasturtiums will start to look tired, and the first frost will finish them off quickly. At that point, pull them up and add them to the compost. But before you do, have a look around the base of the plants for seeds that have already fallen — nasturtiums self-seed enthusiastically, and if you leave the soil undisturbed, those seeds will often get through winter on their own and sprout the following spring without any help from you at all. It’s one of the nicest things about growing them: a single season’s planting can quietly become a recurring fixture in the garden for years.