Sweet Pea

Photographs by Sabina Rüber

Lathyrus odoratus Lady Grisel Hamilton

Lady Grisel Hamilton

Lathyrus odoratus Erewhon

Erewhon

Lathyrus odoratus 'Gwendoline'

Gwendoline

How can you not love sweet peas? Other plants go in and out of fashion, but sweet peas are a universal favourite. Their sweetly-scented flowers have enchanted generation after generation of garden-lovers and they are brilliantly easy to grow, germinating willingly, growing swiftly and flowering lavishly all within a few months. Sweet peas have been cultivated in the west ever since the first wild sweet pea was discovered and distributed by a Sicilian monk called Franciscus Cupani in 1699. (The wild form, now known as ‘Cupani’ is still available and is one of the most highly scented of all sweet peas). Almost as soon as it was introduced, new forms started appearing, including a black-flowered type and a red and white form known as ‘Painted Lady’, which breeders used to make new hybrids, broadening the colour palette to the rainbow of colours we know today. Towards the end of the 19th century, Henry Eckford bred the Grandiflora sweet peas, which had larger flowers than the wild forms, as well as superb scent. Then came the Spencer hybrids, the result of an accidental seedling from Eckford’s ‘Prima Donna’ that had larger, frillier flowers, followed by a succession of new cultivars with ever larger, more showy flowers. The trouble is, if you breed a flower for its size, the other factor, scent, starts to diminish, so that many of the modern flowers aren’t as deliciously perfumed as the Grandiflora types or the wild sweet peas. 

Lathyrus odoratus Cupani

Cupani

Lathyrus odoratus Senator

Senator

Lathyrus odoratus Mrs Collier

Mrs Collier

There’s a huge array of sweet pea cultivars available, so it’s down to you to find your favourites. I tend to choose for scent first and flower second, although having grown luscious dark purple varieties, I now prefer lighter, brighter colours or good old fashioned mixtures such as the ‘Summer Scent’ mixture from Chiltern Seeds. If you want to go for single colour varieties, choose a range that will complement each other in the vase – and this way you can mix the smaller-flowered, strongly-scented varieties with the showier, larger-flowered varieties. So for example you could mix the highly-perfumed ‘Cupani’ or ‘Matucana’ which have small maroon and purple blooms, with the larger-flowered ‘Beaujolais’ or the even showier Spencer sweet pea ‘Windsor’.

Lathyrus odoratus Erewhon in jug

Erewhon

Sweet pea arrangement in jug

Beaujolais & Cupani

Sweet pea arrangement

Romeo & Royal Wedding

Sweet peas are easy to grow but there are a number of things you can do to maximize your success. The first is to sow the seed into deep root trainers which allow the roots the space they need to develop, as well as making it easy to remove them; the root trainers open up like a book so you don’t have to faff around trying to remove the seedlings from a pot, risking root damage in the process. You can sow the seed either in autumn or in early spring; if you sow in autumn you’ll get earlier, stronger plants. Some people soak the seed overnight in warm water which is said to improve germination, but I have never found this necessary. Simply push the seed into moist compost and leave to germinate in a warm place (18-21C) with a lid over the seed tray to keep the soil moist and the atmosphere humid. Unlike most other seeds, sweet peas don’t need light to germinate, so putting black polythene or newspaper over them can help to keep the warmth in (and can also deter mice, who are notoriously fond of nibbling the seeds). As soon as the shoots start curling up, put the tray in a cooler place, ideally an unheated greenhouse or cold frame. If they continue growing inside, they will grow too quickly and become weak and spindly. Treating them mean promotes strong root growth and sturdier plants. Another way to produce a stronger plant is to pinch out the growing tip when they reach about 10cm and have three or four sets of leaves. This encourages more side shoots to appear so you end up with a multi-branching plant that will ultimately produce more flowers. 

When the roots have filled the root trainer it’s time to plant them outside, but harden them off first by leaving them outside for a week or two, and don’t plant out if there’s still a risk of frost. Unless you have the perfect soil, prepare the ground first by adding plenty of well-rotted compost or manure, as sweet peas are greedy feeders. As tendril-producing plants, they need something fine like netting or twiggy pea-sticks to cling onto at first; bamboo canes alone aren’t ideal as they are smooth, but if you are using bamboo, rig up some netting or chicken wire around the frame to get the plants started, and tie them in as they start to climb. Another tip is to water like mad when you first plant them out, otherwise they can sulk and turn yellow, with dry patches on their leaves. Mulching with compost can help to keep the moisture locked in. As the plants climb, keep tying them in, and if you have poor soil, feed them every couple of weeks with a high potash feed to encourage the flowers. Then all that remains is to keep picking as they flower – the more you pick, the more they keep flowering,  so snip away every other day or so and give away plenty of posies to share the joy. 

Back to The Flower Garden Main page