The advantage of sowing sweet peas in autumn is that you get a plant with a very well-developed root system that will romp away when you plant it out in the spring. To encourage root development you should pinch out the stem above the first set of proper leaves. I should have done this a bit earlier, but with such mild weather here they will be fine. In the next week I will transfer them to the coldframe so that they stay cool and concentrate on growing those roots.