Propagation Propagation is exceedingly simple. Seed can be used but, because of the possibilities of hybridisation, you need to either obtain the seed from a known wild source or hand pollinate plants in the garden whilst using some method of excluding pollinating insects from the flowers. Of course, this is only important if you want to breed a species true to type. The seed of cultivars will not usually breed true to type, the seedlings displaying a mixture of characteristics from the parents of the cultivar. Hybridisation has been widely used in order to produce new ornamental cultivars and it does also present the opportunity to start breeding for superior edibility.
Seed is best sown in early to mid spring in a greenhouse.
Use a freely draining compost and cover the seeds to twice their diameter. Germination is usually good, taking place in about 3 weeks from sowing. Prick out the seedlings into individual 3 inch pots in a fairly rich compost as soon as they are large enough to handle and then grow them on in the greenhouse for the rest of the growing season. It is often possible to plant out these seedlings in late spring of the following year but, if the plants still look small or you have a slug or snail problem in your garden, then pot them into larger pots and grow them on for another year before planting out in the late spring of the following year. Division is very easy, and this is the only way of ensuring that named cultivars remain true.