How to Grow Sweet Peas (Lathyrus odoratus) – A Complete Guide
Sweet peas are a timeless favourite in British gardens, loved for their delicate, ruffled blooms and fragrance. Whether climbing up trellises or brightening up a cottage garden border, these annuals are a rewarding plant to grow from seed. Here’s everything you need to know to grow strong, healthy sweet peas in your own garden or allotment.
Sowing Sweet Pea Seeds – when to sow
Sweet peas can be sown between late winter and early spring (February–March) for a beautiful summer display. For stronger plants, you can also sow in autumn (October–November), overwintering young plants in a cold frame or greenhouse.
How to Sow
- Choose a container: Use deep pots, root trainers, or seed trays filled with peat-free, multi-purpose compost.
- Sow seeds: Plant seeds 1–2 cm deep, spacing them out to allow room for roots to develop.
- Watering: Gently water the soil after sowing, but avoid overwatering to prevent rotting.
- Germination conditions: Place pots in a cool greenhouse, cold frame, or bright windowsill. Sweet peas germinate best in temperatures around 10–15°C.
Tip: To improve germination, you can soak seeds in water for a few hours before sowing or gently nick the seed coat with a knife.
Growing Conditions
Light & Temperature
Sweet peas thrive in full sun, needing at least 6 hours of direct sunlight per day. They prefer cooler conditions and may struggle in extreme heat.
Soil & Compost
Use well-draining, nutrient-rich soil with plenty of organic matter. If growing in containers, choose a peat-free compost and ensure good drainage.
Support for Climbing
Sweet peas are climbers, so they need a strong trellis, netting, or wigwam-style supports to grow properly. Put supports in place when planting to avoid disturbing roots later.
Caring for Sweet Peas
Watering
Keep the soil consistently moist, especially in dry spells, but avoid waterlogging. Mulching around the base helps retain moisture.
Pinching Out for Bushier Plants
When young plants reach 10–15 cm tall, pinch out the growing tips to encourage bushier growth and more flowering stems.
Feeding
Feed plants every couple of weeks with a high-potash liquid feed (such as tomato feed) once they start flowering.
Deadheading & Cutting Flowers
- Deadhead regularly to keep plants flowering for longer.
- Cut flowers frequently – the more you pick, the more they bloom! Harvest stems when 1–3 blooms in the cluster are open for the best vase life.
Common Problems & Solutions
Poor Germination
- Ensure seeds aren’t overwatered.
- Scarify (nick) or soak seeds before sowing if the seed coat is very hard.
Leggy Seedlings
- Provide plenty of light to prevent stretching.
- Pinch out tips once seedlings are established.
Powdery Mildew
- Ensure good airflow around plants.
- Water at the base, not over the leaves.
Aphids
- Wash off with a jet of water or introduce beneficial insects like ladybirds.
Why Choose Wild Wood Growers’ Sweet Pea Seeds?
Our sweet pea seeds are produced from organically grown plants in our herb and flower garden, cultivated without synthetic chemicals and using regenerative growing practices. Each seed is hand-selected and saved using traditional methods, ensuring strong, resilient plants that thrive in UK gardens.
Sow, grow, and enjoy the scent of summer! Buy sweet pea seeds here.