The scent of sweet peas is like no other, and a vase of cut blooms filling a room with fragrance is reason enough to grow these cottage-garden favorites. In warm areas, sow seeds in the autumn; in colder parts sow in spring in a warm greenhouse or on a windowsill. Grow them on in an open, sunny area.
When to plant: Autumn or early spring.
At their best: Summer.
Time to complete: 2-3 hours over several months.
You will need: Sweet pea seeds, sharp penknife or nail clippers, deep seed trays or root trainers, seed soil, well-rotted organic matter, obelisk or bamboo canes, garden twine, all-purpose liquid feed.
Chip the seed
Sweet pea seeds have a hard shell, and unless water can penetrate it, the seeds will not germinate. To ensure the seed absorbs water, use a sharp penknife or nail clippers to carefully nick it opposite the “eye” (small, round scar) and remove a small piece of the seed coat.
In autumn, fill trays or pots with seed soil and sow the seeds ½ in (1 cm) deep. Keep the seedlings in a cool greenhouse or cold frame until the following spring, only providing extra heat during severe frosts. In mid-spring, remove the tip of the main shoot from each seedling.
If you sow sweet peas in early spring, grow the seedlings indoors, or in a warm greenhouse, at 58–62°F (14–17°C). When they reach 4–6in (10–15cm) high, remove the tips down to the first set of leaves. Pinching out the tips like this encourages side shoots to form.
Harden off and plant out
Autumn-sown seedlings can be planted out directly into the ground in mid-spring. Spring-sown seedlings will have tender shoots that need to be hardened off for a few weeks by bringing them outside by day, and inside at night. Plant hardened seedlings out in late spring.
Enrich the soil with well-rotted organic matter and plant one or two seedlings close to the base of a suitable support and tie them in loosely. The tendrils will soon take hold of the supports as the plants grow. Water during dry spells, and apply a liquid feed every two weeks from midsummer. Pick the flowers regularly to encourage more.
Tips: Home-made seed pots
Roll folded newspaper around a glass and tuck the top ends into it. Remove, then flatten the tucked-in ends to form the base. Plant seedlings and their pots into the soil—the pots will just rot away.
Sweet pea supports
Sweet peas climb using their twining tendrils, which cling to slim supports, such as sticks or bamboo canes. These bushy plants reach up to 6 ft (1.8 m) high, so make sure your support is tall enough to accommodate them.
Wooden or metal obelisks and tripods are ideal for sweet peas, and make decorative additions to flower borders or to vegetable beds, where you can plant them alongside runner or French beans. (Do not confuse the pods when harvesting because sweet peas are poisonous). You may find that young plants struggle to take hold of smooth materials, such as metal, or do not cover the whole support evenly. To remedy this problem, wind some string around the poles and tie it horizontally across the legs of the support to provide the plants with more grip.
Make your own
It’s easy to make your own sweet pea supports by setting out bamboo canes to form a wigwam and tying them securely at the top. Alternatively, grow them up pea sticks, or create a support with plastic mesh wrapped around a circle of sturdy stakes driven into the ground, securing the trellis with garden twine or wire. As the plants grow, these supports quickly disappear beneath the flowers and foliage.