Sweet peas have a special place in the hearts of gardeners, with a romance that exceeds their usefulness for garden display, I often think. This is not to say for a moment that I do not rate them or that I would not grow them. They, with calendulas and nigella are the only hardy annuals that I grow every year. But whereas most hardy annuals require minimal attention, sweet peas are needy. Now it is true that you could sow the seeds where they are to flower, in March, let them scramble up some netting or over a shrub and they will flower, and the blooms will be as big and as fragrant as if you paid the plants more attention. But it is not as simple as that because the plants will not grow that well, the flower stems will be short and twisted, the plants will, quite frankly, look scruffy and they will not flower for long. This is because the Spencer, and to a large extent Multiflora, sweet peas have been ‘domesticated’ for so long that they are not great garden plants – they have been bred for their flowers rather than as plants. And then there is the key issue of seed production – if you let a few faded flowers remain on the plant so they form seed pods the plants don’t bother to produce more.
Now there are some exceptions and for clambering up shrubs or to grow in a pot up a tripod of canes I would recommend the Grandiflora sweet peas or the new ‘Solway’ varieties. The ‘Solway’ sweet peas are almost miniature climbers reaching about 1m high with small leaves and flowers on short stems and are much better for pots than regular types.
Sweet peas are hardy annuals and the plants can withstand light frost. The seeds can be sown in autumn or in spring. For best results it is generally accepted that autumn sowing is best, possibly because the slow growth over winter results in stronger root growth. Last year I sowed in spring and grew the plants up canes among beans but this year I am planting in March from October sowing and growing the plants up canes, on the cordon system, for better flowers.
The seeds do not need high temperatures to germinate – 10c or above is fine. I sowed the seeds, in late October singly in cell trays.
They were kept in a cold greenhouse. They must be protected from mice which will destroy your plants overnight. Do not let them get dry.
For some reason the initial stem that grows is never the strongest so when they are about 10cm high pinch out the shoot tip to encourage new, stronger shoots from the base. When planting out these can all be left but because I will be growing them as cordons, as single stems, I will remove all but the strongest a few weeks after planting out. Last week I repotted these seedlings into 10cm square pots so they can develop a good root system before planting out, probably in mid March if the weather is mild.
This area was used for growing sunflowers last year and masses of manure was added as mulch and then dug in. The soil has been mulched with mushroom compost.
It is not too late to sow now and you can sow the seeds in heat indoors now and until the end of March. Sow seeds in 10cm pots with two or three seeds per pot for ease. Sweet peas do not like root disturbance so do not sow them in trays and transplant them.
Tip – Sweet pea buds do not open when cut so only pick fully open flowers
Classification of sweet peas:
The origin of sweet peas was, for some time, confused but it is thought that they were first noted in the wild and written about by theFranciscan monk Francisco Cupani in 1695 in Sicily. He gave seed to Casper Commelin, a botanist in Amsterdam in 1699 The plants produced small blue and purple flowers with intense fragrance. Amazingly this is still available today as ‘Cupani’. It is though that seeds were also sent to Dr Robert Uvedale in Enfield, Middlesex. The plant progressed slowly with little variation in colour until Henry Eckford, at the end of the 19th century hybridized existing varieties and introduced the Grandifloras.
Grandiflora. These had larger flowers than the wild sweet peas with a wide variety of colours. They were very popular. They have two or three flowers per stem and 20 or more of his varieties are still available. However, the real rise of sweet peas began in 1901.
Spencer. In 1901 Silas Cole, Head Gardener to the Earl of Spencer found a natural mutation among the Grandifloras with larger, wavy petals and these were named Spencers. They flower slightly later than the Grandifloras and have three to five flowers per stem – four or five for showing.
Multiflora. These are developed from the Spencers and have slightly smaller flowers with less ruffled petals but have at least five flowers per stem. They are not so good for exhibition