Enduring beauty

Loved for its fragile petals and heady perfume, the sweet pea is the very essence of summer

There’s something about sweet peas (Lathyrus odoratus) that gladdens the heart, even in the soggiest of English summers. It’s partly the way they grow, with visible energy, their tendrils propelling them towards the light, flaunting their flowers to the pollinators in order to set and disperse their seed.

But it’s the heady scent and exquisite colours that make sweet peas for many of us the very essence of the garden in summer. They are also a favourite cutting flower – even a modest posy in a simple vase looks beautiful and perfumes a room.

Sweet peas are grown scrambling up arches and obelisks in the border, in tidy rows in the kitchen garden, or up a wigwam in a corner of the allotment.

They are easy to grow from seed, producing the best results if sown in October or November. The advice from the Royal Horticultural Society (RHS) is to sow individual seeds in root trainers or 9cm (3in) pots filled with seed compost. Cover the seeds with compost, water in, then cover the pots with clear polythene or glass, and keep at 15C.

After germination, remove the covering. Overwinter in a cold frame, removing the growing tips when the plants are about 10cm high to encourage bushy growth. Keep the cold frame open as much as possible, but protect from heavier frosts. Plant out after the last frosts. For a long supply of flowers, cut every day to prevent seed setting.

The RHS recommends three Lathyrus odoratus cuItivars that are particularly strongly scented. They are: ‘White Supreme’, ‘Charlie’s Angel’, which has large pale blue flowers, and ‘Gwendoline’, a frosted pink. All of these are Spencer sweet peas, the modern, large-flowered strain that is the standard exhibition pea. They were found growing at Althorp, home of the Spencer family, hence the name.

‘Charlie’s Angel’, which is particularly long flowering, was the first Spencer sweet pea to receive the RHS Award of Garden Merit (AGM).

The RHS has 37 different cultivated varieties growing in this year’s sweet pea trials at RHS Garden Wisley in Surrey. Planted out in impeccably measured rows in Wisley’s beautiful trial field, the sweet peas are being assessed by the relevant RHS subcommittee for the excellence of their flowering habits, their colour and trueness to form. The cultivars that meet the criteria will receive the coveted AGM, which is reserved for plants of excellent gardenworthiness. Visitors are invited to vote for their favourite sweet pea in the trial; voting papers are available at the trial plot. The results of the vote will be published by the RHS at the end of the flowering season.

I grow sweet peas in a large pot in the garden, training them up a willow obelisk, and in the cutting bed at the allotment on a wigwam made of hazel sticks held together with twine. My favourite is ‘Cupani’, the ‘original’ sweet pea, recorded in 1699 as being sent by a Sicilian monk, Cupani, to contacts in Holland and the UK. ‘Cupani’ has small, velvety flowers in slightly clashing and hugely satisfying tones of deep violet and maroon. The colouring is striking and the scent irresistible.

The perennial sweet pea, Lathyrus latifolius, while coarser than the annual variety, has its uses for covering walls and unsightly sheds. ‘White Pearl’ is less vigorous than the magenta form.

Lathyrus vernus, on the other hand, commonly known as spring vetchling or spring pea, is a low-growing bushy little plant, with mauve flowers. It is useful placed at the front of the border between later-flowering plants that will fill the gap when it dies down after flowering in midsummer.

On the allotment, the mangetout pea, Pisum sativum ‘Carouby de Maussane’, an old French variety, racing up its wigwam, is producing the quantities of flat, tender pods that follow on fast from its attractive purple flowers. Not a sweet pea, but sweet to eat.

Royal Horticultural Society: www.rhs.org.uk

Gardening with Mrs Obama

First Lady Michelle Obama’s handsome and engaging first book is a lively example of a new genre – the vigorous hybrid.

It’s the story of the White House Kitchen Garden, which was started in March 2009, and the children, volunteers and staff who plant, tend and harvest it. The book is also a rallying cry to America to ‘grow a healthier nation’, and an opportunity to promote Michelle Obama’s campaign to tackle obesity in children, Let’s Move!

The book is organised according to the seasons and what has been planted year by year. It is enjoyably sprinkled with items on, for example, the history of the gardens at the White House; and it gives some glimpses of the First Lady’s childhood in Chicago, where her father as a boy worked on one of the vegetable trucks that brought food to neighbourhoods direct from the farm.

It’s a beguiling book, beautifully produced, with gorgeous photographs and heaps of recipes.

American Grown: The Story Of The White House Kitchen Garden And Gardens Across America (Ebury Press, £25).

Plant of the week

Gillenia trifoliata is an airy, but tough, herbaceous perennial with star-shaped white flowers that catch the breeze, and flush bronze in autumn. It flowers for weeks in midsummer and looks good in a border, particularly with roses. Height and spread: 1m. £4.50 for one plant or £12.50 for three: www.claireaustin-hardyplants.co.uk