Nasturtium (Tropaeolum majus) is one of the quickest and easiest hardy annual flowers to grow, producing masses of vividly coloured blooms through summer and autumn. They’re perfect for growing with children. Nasturtiums come in both bushy and climbing varieties, which makes them splendidly versatile. Some varieties have attractively marbled or mottled leaves. Nasturtiums not only look spectacular but the flowers, leaves and seeds are edible too. Bees love the colourful nasturtium blooms, and caterpillars of the large and small white butterflies feed on the leaves.
Being annuals, nasturtiums complete their lifecycle in one growing season.
How to grow nasturtiums
Nasturtiums are ideal for lots of different sunny spots around the garden, including pots. Climbing varieties of nasturtium can be trained up vertical supports and are great to twine through other plants too. Nasturtiums that are climbers can also be used as trailers – to spread across gravel or cascade down a slope or bank. Free-draining soil is essential for nasturtiums and, unlike many other flowers, they thrive on poor soils.
Nasturtiums: jump links
- Where to grow nasturtiums
- How to plant nasturtiums
- How to propagate nasturtiums
- How to harvest nasturtiums
- Nasturtiums problem-solving
- Types of nasturtium to grow
More on growing nasturtiums:
Where to grow nasturtiums
Nasturtiums must have sun for at least half the day in order to grow well and do best in sites sheltered from winds. A free-draining soil is essential, and nasturtiums flower best in poor soils (that are low in fertility) as a fertile soil results in lots of leafy growth at the expense of flowers. Hence there’s no need to add fertilizer before sowing. Nasturtiums do well in gravelly or stony ground or growing on banks. In containers, mix two-thirds peat-free multi-purpose compost with one third fine gravel or grit, to reduce fertility and ensure good drainage.
In this clip from Gardeners’ World, Monty Don arranges plants for a late summer display, with a dramatic purple-leaved Phormium cookianum ‘Black Adder’ in the centre, lots of magenta-flowered Cosmos bipinnatus ‘Dazzler’, and four Bidens ‘Hawaiian Flare Orange Drop’ cascading over the rim, alongside trailing nasturtiums, Tropaeolum majus ‘Cherry Rose Jewel’. He also advises on aftercare to keep the display at peak flowering through to late autumn:
How to plant nasturtiums
For best results, sow nasturtium directly where they are to flower, as they’re fast-growing and there’s no need to bother about transplanting. Sow the seed 1.5 cm deep into moist soil to speed germination, so water before planting if conditions are dry. The first seeds can be sown in mid-spring and you can carry on sowing until mid-summer to ensure flowers right up to the first frosts. Thin the seedlings to 30 cm apart.
However, sowing in pots also works – simply sow one seed per pot and transplant outside when all risk of frost has passed.
How to care for nasturtiums
Nasturtiums are easy-care and need little maintenance. Plants growing in containers should be watered to keep the compost evenly moist, but not fed. Removing the dead flower heads of nasturtiums will encourage more blooms to be produced for a longer period.
How to propagate nasturtiums
Nasturtium seeds can be collected when ripe and saved to sow next year. In mild areas, nasturtiums are also likely to self-sow, so you may get seedlings springing up in future years. These can be easily pulled up if not wanted.
How to harvest and use nasturtiums
Nasturtium leaves, flowers and seeds are all edible. The flowers make a brightly coloured garnish to salads and other uncooked dishes. Nasturtium leaves have a peppery taste and should be picked when young to incorporate in salads. Nasturtium seeds can be used as a substitute for capers and should be picked when mature but still green, for pickling in vinegar.
Growing nasturtiums: problem solving
Nasturtiums are likely to attract large and small white butterflies (known as cabbage white butterflies) which lay their large greenish eggs on the leaf undersides, which hatch into caterpillars that eat the leaves. This can be useful to deter caterpillars from eating brassica crops but not desirable if you’re growing nasturtiums for flowers. The best method of control is to inspect plants regularly and squash the eggs or young caterpillars, or move them on to plants you don’t mind being eaten. Nasturtiums are also attractive to aphids, particularly blackfly. Again, by planting nasturtiums alongside bean crops you can lure aphids away from your crop, but you may not appreciate aphids on nasturtiums you’re growing for leaves and flowers. Spray them off with a jet of water or let ladybirds, hoverflies and lacewings remove them for you – all three lay their eggs on aphid colonies and their young quickly eat them up.
Nasturtium varieties to grow
A wide range of annual nasturtium (Tropaeolum) varieties is available by mail order from seed companies, or from garden centres. Choose from mixed flower colours or opt for individually coloured varieties to create coordinated planted schemes.
- Nasturtium ‘Alaska’ – flowers in yellow, orange and red are shown off against cream and green marbled leaves. Bushy, 30 cm high.
- Nasturtium ‘Empress of India’ – crimson-red flowers and dark reddish leaves. 25 cm high.
- Nasturtium ‘Milkmaid’ – Creamy-white flowers on climbing/trailing stems. 180 cm high.
- Nasturtium ‘Paintbox Mixed’ – a mix of brightly coloured flowers that are more upward facing and hence visible than most. 30 cm high.
- Nasturtium ‘Salmon Baby’ – bright salmon pink flowers. 30 cm high.
- Nasturtium ‘Tip Top Velvet’ – dark red blooms that show off well against fresh green foliage. 30 cm high.
- Nasturtium ‘Trailing Mixed’, ‘Tall Mixed’ – masses of orange, yellow and red blooms on long stems that can climb or trail. 180 cm high.