Breeding programmes have concentrated on producing large flowers with ruffle-edged petals on tall straight stems, and have given scarcely a thought to scent. What a stupid, myopic catastrophe this is. What do they think you grow sweet peas for? You want them for their scent, not just for their pretty regularity in a vase.
To get good, powerful scent you need to return to the old-fashioned varieties, or ones that have been bred directly from them. Most of the general seed catalogues now stock only the showy, modern forms, and the better varieties hardly ever appear in them. But a specialist seller, Peter Grayson (www.igarden.co.uk/petergrayson/), has a huge selection. You should go straight to him.
Most of Grayson's hybrids have been bred from old-fashioned sweet peas, which have a strong scent and a delicate form close to that of their ancestors, which grow wild in the Mediterranean and South America, where they were first collected by Europeans in the 16th century. Grayson also has a few of the modern `Spencer' varieties, such as the lovely and brilliant pink `Mrs June Grayson', and `Gypsy Queen', which has large ruby red flowers. These varieties have some scent, but are not in the same league of fragrance as the older forms.
The ones you really want are varieties such as Lathyrus odoratus `Matucana', with deep purple wings and a redder snout. Each individual flower has a scent as strong as a whole bunch of the modern types. There is also a lovely, dark maroon `Black Knight', which I grow every year, and a sweet, small-flowered pink and white `Painted Lady'.
Order your seeds now, so that you can sow them by the middle of April. You'll need some 9cm (4in) diameter pots and multipurpose potting compost. Sweet peas, like most legumes, thrive on long roots and with root disturbance kept to a minimum, so if you can find deep pots, so much the better. You are often told to soak the seeds to speed up germination, but don't bother. Some of them rot very quickly when left in water.
Plant two seeds in each pot, about 2.5cm (1in) below the surface, and cover them to exclude light. Place the pots on a cool windowsill or in a frost-free cold frame. You could try setting a mousetrap if you are leaving them outside. Mice think sweet pea seeds are delicious and, if given half a chance, will snaffle the lot.
The seeds will germinate after about 10 days. You need to check every day for any signs of green, then remove their covers and give them good light. Keep them cool so that they put their energy into growing roots not stems and leaves.
If you don't want to sow your own sweet peas you can buy seedlings from Midway Nurseries. They don't have old-fashioned varieties in single colours, but do a mixed pot (minimum order five pots) of six plants for pounds 2.80, including delivery. These grow into good, strong plants.
In early May, make a tepee out of cane or pea sticks and plant out the sweet peas, 5-7cm (2-3in) away from the base of each of the poles. Protect each plant from slugs with a 5cm (2in) ring of grit and, as the plants begin to grow, tie them into the frame.
Lots of people talk about pinching out their sweet peas. This means removing the growing tip of the seedling, which should make it bulk out and form a bushier plant. You are also told to remove the buds that grow between a leaf and a stem, including the corkscrew stems that hold the sweet pea on to the cane.
You can do all these things to get perfect, long straight stems - but you will still have a cloud of flowers and an incredible scent if you don't. The only thing that you absolutely must do is keep picking the flowers. If you let your sweet peas run to seed, they will quickly finish flowering.
Peter Grayson Sweet Peas (01246 278503). Midway Nurseries (01597 851662)
1 Half-hardy annuals sown and pricked out a few weeks ago may now be ready for potting on. White, tendrilly roots creeping out from the holes in the bottom of each pot are a sign that it is time. Carefully tip out each seedling on to a bench and replant into a pot one size larger. Don't drown them in a huge pot, they seem to do better if kept slightly hungry, so the roots grow more quickly as they scrabble for foodReuse content