Early Spring is a good time to start growing herbaceous plants from seed. It is quite incredible – and a little daunting - to see the number of options available in seed catalogues, especially when you are new to propagating.
Over the years we have tried and tested LOTS of different seeds and while many are excellent, others have been sadly disappointing. For example, we thought Knautia macedonica would be simple to grow because it self-seeds so freely in the nursery garden, but we found when we collected the seed for spring sowing the germination rate was rubbish! In light of our own findings we wanted to share some of our best seed-growing finds with you so that you can give them a go for yourselves.
Some of our fool-proof plants to grow from seed are Gillenia trifoliata (not the best germination rate but good enough to be worth having a go), Lysimachia ephemerum (tiny, dust like seed results in a substantial sturdy plant indistinguishable from a cutting grown one), Erodium manescavii and Berkheya ‘Silver Spikes’. We also love Geranium ‘Dark Reiter’ and Anthriscus sylvestris 'Ravenswing’ (be sure to pick out and throw away the green seedlings) for their dark foliage.
Simply grow any of these seeds indoors or under glass using a good quality, low-nutrient seed compost and a bit of warmth. When the first true leaves appear, prick the individual seedlings out and pot on into single modules. Once the seedlings are 4-5 inches high, harden them off gradually outdoors or in a cold frame and plant out once risk of frost has passed – usually the end of May. With the darker foliaged plants, select the seedlings with the darkest colour foliage to prick out and pot on for the best results.