Sweet pea (Lathyrus odoratus) is a gorgeous fragrant-flowered climber and a long-established garden favourite that makes a pretty cut flower, perfect to pick for posies – just a few stems can scent a whole room. Or simply grow them in the garden, trained up an obelisk or ‘wigwam’ of twigs you can achieve a cottage look that costs almost nothing. There are hundreds of different sweet pea varieties to choose from, sold in individual colours or in mixes. Some are more scented than others, however, so read the description carefully if it’s the fragrance that you’re after.
When to sow sweet peas
Sweet peas can be sown from October to April. Autumn-sown sweet peas bloom earlier, while spring-sown plants flower later. April is the last month to sow sweet peas so don’t delay: plant now for fragrant blooms this summer.
How to sow sweet peas
- Fill pots with moist, peat-free multi-purpose compost, firming gently to ensure there are no air spaces. Using your finger, or a pencil, make a hole 1cm deep in each container. Drop a single seed in each hole and cover with compost.
- Place the pots in a warm place – a heated propagator is ideal, or anywhere warm indoors.
- As soon as the first shoots appear, move seedlings to a cool place in good light, either indoors, in a cold frame or porch, or an unheated greenhouse. If kept in warmth, seedlings will become thin and leggy.
- Water as necessary to keep compost moist but not wet. Once the young plants have several pairs of leaves, pinch out the growing tip of each one, which encourages bushy growth.
Planting, growing, and training sweet peas
- Harden off, or acclimatise plants to the outside, over a period of a couple of weeks, standing outdoors for increasing periods of time or opening a cold frame lid.
- Plant out in May once your sweet peas are bushy and well established, spacing plants around 20cm apart. Sweet peas like rich soil, plenty of sun, and prefer a sheltered site. Put supports in place before planting and tie in plants using soft string.
- Water in immediately to settle the soil around the roots, and then as needed to keep moist.
- Protect from snails and slugs using an environmentally friendly bait or a barrier. This is usually only needed in the early stages whilst plants are small.
- Train in growth once or twice a week. While sweet peas are mainly self-clinging, by means of tendrils, wayward stems often need tying in.
- Once the first flowers appear, start feeding weekly with a high-potash liquid fertiliser.
Tips for success
Sow seeds seeds individually in narrow, deep pots, as sweet pea seeds produce long roots and struggle if disturbed. Why not save the cardboard inners from toilet and kitchen rolls or buy biodegradable or reusable pots?
Pick blooms frequently to encourage more flowers to be produced. Remove spent flowers and any seed heads promptly, as flowering declines if plants set seed.
