Delphinium Seeds - hybridum Seeds New Century Ref: TM01402991 SowingSow from late winter to early summer 3mm (1/8in) deep in a good seed compost. Make sure that the compost is moist but not wet and seal in a polythene bag until after germination which usually takes 1-3 months at 10-13C (50-55F).<p>They can also be sown outdoors in spring where they are to flower.GrowingTransplant when large enough to handle into 8cm (3in) pots. Later plant out 60cm (2ft) apart into a deep rich well drained soil in a sunny position with some shelter.Aftercare FloweringSummercroppingPlant typeHardy Herbaceous Perennial Price: £2.49 Quantity: