How to care for nasturtiums, the fuss-free flower for every garden

The garden nasturtium, Tropaeolum majus, is a fuss-free Peruvian annual that produces flame-like flowers, in shades of gold, orange, and red, throughout summer and into autumn. The flowers bloom amongst a mass of green leaves, which are round and supported from underneath by stalks, making them look like miniature waterlily pads.

Fond of poor, well-drained soil and sunshine, they are excellent plants for a warm wall or a gravel garden or for edging a path, as seen in Monet's garden at Giverny. The painter originally planted trailing nasturtiums by mistake, thinking they were dwarf clumping forms, but he so enjoyed the way they rambled across the path, that they were grown that way year after year.

The plant's common name comes from the Latin species name for watercress (Nasturtium officinale) because both have plants have an equally peppery flavour and aroma. The word nasturtium derives from the Latin nasus tortus (twisted nose) because – as anyone who has handled or picked nasturtiums will confirm – their odour has a strange effect on your nostrils, making them tingle and sting.

Annual nasturtiums are great plants for the vegetable patch, providing a blast of colour and luring unhelpful insects (such as cabbage whites and aphids) away from crops. On top of that, they are great culinary flowers, having a wonderful spicy taste. In her recent book, A Floral Feast - A Guide to Growing and Cooking With Edible Flowers, Foliage, Herbs and Seeds (Pimpernel Press), Carolyn Dunster writes, 'My number one plant for starting an edible flower garden is the nasturtium. It is especially useful as all its parts are edible.' The colourful flowers make a fabulous garnish or cake decoration. Both the flowers and the leaves have a delicious fiery flavour and work well in salads and fish dishes. The seedheads are sometimes referred to as poor man's capers, having a similarly tart taste; Dunster suggests pickling them in cool, boiled white wine vinegar.

As if all that wasn't enough, these stalwart annuals are also superb wildlife plants, luring bumblebees and other insects. Regularly deadheaded, they can bloom into late autumn, and will then self-seed to provide you with a mass of colour the following year.

For bold colour, the ultimate annual nasturtium is 'Empress of India', having rich purple-green leaves and blazing orange-red flowers. Trailing slightly (to 45 centimetres or more), it is great planted on its own in a hanging basket; if deadheaded, it will be a tumble of furnace colour for months. Also fabulous are 'Cherry Rose Jewel' (semi-double pink-red flowers), 'Baby Rose' (small fuchsia-pink blooms) and 'Black Velvet' (smouldering chocolate-red flowers), all of which form 30-centimetre mounds, making them perfect for pots or the edge of a border. Two good climbing forms are 'Indian Chief' (scarlet blooms and dark bluish leaves) and 'Spitfire' (red-orange flowers and green leaves) – rambling to 1 to 2 metres, they will clad a wigwam of hazel sticks or an obelisk.

Softer colours aren't associated with nasturtiums, but there are plenty on offer, including 'Gleam Salmon' (a trailing or climbing form with pale apricot blooms) and 'Whirlybird Cream' (a compact mound of primrose and butterscotch flowers). 'Vesuvius' is a bushy heritage variety with gentle-coral blooms and 'Purple Emperor' is a trailing form with velvet-red flowers that fade to a lovely shade of dusky purple.

The perennial nasturtiums are not widely grown, but some of them are excellent plants. The hardiest is the stunning flame creeper, Tropaeolum speciosum. An herbaceous climber from Chile, it produces vivid vermilion-red blooms during summer and autumn and loves gardens with cool, moist summers. Its feet demand acid to neutral soil in shade or semi-shade, but it likes to grow up into full sun; a climbing frame plant (such as a dour conifer you want to liven up) will provide the support it needs.

T. tuberosum var. lineomaculatum 'Ken Aslet' is another colourful perennial climber, but much smaller; in summer and early autumn, it has long-spurred orange and yellow blooms that resemble shoals of tiny fish, above the attractive mass of blue-green leaves. Being tender, it is best to either lift the tubers when the temperature plummets or grow it under cover, if you don't live in a coastal or mild region.

T. polyphyllum (yellow lark's heels) is a much smaller scrambling plant for a sunny wall; it grows from tubers and has gorgeous glaucous foliage topped with yellow flowers in early summer; although it dislikes extremely cold winters, it relishes a cool climate and therefore does well in coastal gardens.

• Sow or plant: having big seeds, annual nasturtiums are very easy to sow and great plants to grow with children. Sow between March and June, either into module trays under cover or direct outside. Alternatively, buy ready-grown bedding plants in May or June. If your garden is plagued by slugs, sowing direct is living dangerously – home-grown (or bought) plug plants are a safer bet!
• Light: a site in full sun is best.
• Soil: annual nasturtiums dislike rich earth – poor soil is ideal, and there is no need to feed them. They are fantastic plants for shallow soil too.
• Water: in hot, dry weather, water regularly. But never overwater nasturtiums.
• Site: as long as they have good drainage and sun, nasturtiums will grow anywhere, from hanging baskets to ornamental borders. You could even grow them on a sunny
• windowsill as a baby salad leaf crop (try 'Blue Pepe', which has small blue leaves).
• Pests: guard annual nasturtiums (especially seedlings) from slugs and rabbits.
• Harvest: keep picking the flowers to use in salads or cooking and deadhead spent flowers and the plant will respond by producing more.
• Safety: the herbalist Jekka McVicar advises eating annual nasturtiums in moderation: no more than 15 grams in one sitting and no more than 30 grams per day.

Plant abundantly in the vegetable patch to lure cabbage white butterflies and flea beetles away from brassicas; Cleome (spider plants) have a similar effect. Nasturtiums can be used as a sacrificial crop to lure aphids away from other edibles; they will also attract hoverflies, ladybirds, and lacewings, which lay eggs on the plant so that their young can gobble the aphids. Nasturtiums are also said to repel whitefly, if planted near susceptible crops, such as tomatoes.