Sweet Peas: A Sowing Guide
Sweet peas are a classic favourite, filling gardens with their delicate blooms and irresistible fragrance. Our nation’s sweet pea captain, Roger Parsons, recommends sowing them in late October, and we sow ours around then too. If you get yours in the soil between October and November, just before winter truly sets in, you’ll be in fine company.
If you don’t have a cold frame or greenhouse, it’s best to wait until spring to sow, as sweet peas need a protected space to overwinter successfully. We do our second sowings from late January through to late March.
Choosing the Right Compost
Use a multi-purpose compost rather than a fine-textured seed compost—sweet peas need plenty of air around their roots to thrive.
Best Pots for Sowing
9 cm pots – Our favourite choice!
Root trainers – Ideal for deep root growth.
Seed trays – Can work, just ensure enough space for roots and pot up when required.
Step-by-Step Sowing Instructions
Fill your chosen pots with compost, leaving a little space at the top.
2. Sow 2–3 seeds per 9 cm pot (or space them accordingly in trays/root trainers).
Make a small hole (~2 cm deep) with your finger or a dibber.
Drop one seed into each hole.
3. Cover the seeds with compost—sweet peas require darkness to germinate.
4. Label your varieties! Sweet pea seedlings all look the same until they flower.
5. Water gently after sowing. Then hold off on further watering until germination occurs—too much moisture can cause the seeds to rot. Don’t let the soil completely dry out though!
If the compost starts drying out, mist lightly with a watering can fitted with a fine rose.
6. Provide the right temperature for germination:
15–18°C (59–64°F) is ideal.
Place in an unheated greenhouse or a cool room indoors. If the weather is on the colder side, you can speed up germination with a heat mat and a propagation lid/or sandwich bag.
7. Protect from mice! Sweet pea seeds are a favorite snack for rodents. Keep trays off the ground or use a ventilated propagator lid.
8. Grow on cold and in the light! As soon as germination occurs, you’ll want to move them somewhere cooler to grow on with lots of daylight. They can easily tolerate temperatures down to -4°C. The cold will encourage root growth over vegetative growth. This is essential for the most robust plants.
Germination Usually takes 7–14 days.
