Now’s the perfect time to sow sweet peas, but bear in mind what type you’re planting. There are three types of sweet peas: winter-flowering, spring-flowering and summer-flowering, with the majority of varieties available in New Zealand being summer-flowering. Autumn is the best time to sow seeds of winter and spring blooming sweet peas, but summer-flowering types grow better if sown in short days (winter) and grown on into lengthening days. That means June to August is the best time to plant summer-flowering sweet peas, but sowings can, in fact, be made up until mid-October. In very cold areas it might be best to leave sowing until spring.
Sweet peas like a sunny spot in well-drained, humus-rich soil. You can sow them in pots to transplant later or sow them directly in the ground. If you start them off in pots, though, leave the containers outdoors, not in a greenhouse. Sweet peas germinate at low temperatures; strong plants result if grown in high light and cool conditions. Spindly, sprawling ones often result if grown in a greenhouse.
Some people soak their seeds overnight before sowing, but it’s not necessary, so long as you sow your seeds into a moist bed.
You can apply a fertiliser at planting time, but there’s no need to go overboard. Use a balanced fertiliser (I like Nitrophoska Blue), one that is not overly high in nitrogen. Scatter snail pellets around your seedlings too, as snails love the tasty young leaves that emerge.