Keep picking sweet pea
If you grow sweet pea, it's essential to keep picking the flowers. If you leave them to fade on their stems, they form pods, and the plant will think it has performed its duty of self-perpetuation, and will cease flowering. So pick big bunches regularly, and bring them into the house. Sweet peas also need plenty of moisture, so keep them well watered if they are in pots, or in a dry part of the garden. And, if you didn't incorporate lots of nutritious manure or garden compost when you planted them, they will appreciate a shot of plant food every couple of weeks during the season.