The myriad colours and delicious scent of the sweet pea have made this popular annual as synonymous with the summer cottage garden as the English rose.

These easy-to-grow climbers are at home in borders, weaving their way up wigwams and obelisks or scrambling through shrubs, or in the vegetable garden grown with green beans, encouraging pollinating insects to the area which will in turn create a better crop.

“The key to every sweet pea is the size of its root. The longer you can allow the roots to grow, the better blooms you will have during the summer,” says Lady Ursula Cholmeley, owner and manager of Easton Walled Gardens in Lincolnshire, which raises hundreds of sweet pea plants from seed in the greenhouses, which can be seen in full bloom during Sweet Pea Week next week. Gardeners whose sweet peas are looking weak and wishy-washy should boost them with a foliar feed which you can attach to your garden hose or dilute with water in a watering can. A feed such as Growmore is ideal, she says.

“However, if you’ve prepared the soil well beforehand, adding plenty of organic matter, you shouldn’t need to feed them,” she notes.

You can sow them twice a year, once in late autumn and again in spring, to ensure a succession of blooms throughout the summer. Autumn-sown plants flower in early summer, spring-sown varieties later on in the summer.

Sow sweet peas in autumn in a cool greenhouse or cold frame in regular potting compost. Once the seedlings start to grow they need to be kept as small as possible, so avoid giving them any warmth.

They can be planted out in spring, from March onwards, in a sunny position and will withstand light frost but not a more severe hoar frost, so keep a check on weather forecasts and protect them with horticultural fleece if a harsh frost is predicted.

Spring-sown varieties can be sown directly into the ground and should flower later on in the summer.

At Easton Walled Gardens, spread over 12 acres, more than 50 types of sweet pea – heritage, modern, scented, striped, edged and bi-colour sweet peas – are displayed on canes, drums and wigwams throughout the pickery (cut flower garden), vegetable and cottage gardens.

All sweet peas need to be staked and many gardeners use wigwams or other supports to show them to their best. However, the plants can only cling to narrow supports, says Cholmeley.

“Sweet peas cannot climb up bamboo because it’s too wide for their tendrils, so you need to put netting around a wigwam. They need full sun to develop their scent.

So if you haven’t yet had a go with sweet peas, buy a packet of seeds and start this autumn – and by next summer you should be enjoying the sweet smell of success.

For more information, go to eastonwalledgardens.co.uk.