Should I leave my imperials to self seed?
Q I left my crown imperials to die back and some produced seedpods. Will they weaken the plant if left to mature, or can I leave them to self-seed?
Cath Matlake (via email)
A
Fritillary seeds are relatively easy to grow and this could be a cheap way to bulk up your plants.
The seed is ready when the seedpod has gone brown and started to split. Seeds should be sown immediately and kept somewhere cold (but free from frost) for the winter and should germinate the following spring.
Young plants are best grown on in containers for two years before planting out, to make sure they are big enough to survive in the garden.
However, allowing a plant to set seed, particularly a bulbous plant, might have an impact on the growth or flowering the following year, because producing seeds is quite an energysapping business for plants and it diverts energy from being stored in the bulb for future growth.
You can help the plant along by making sure it has plenty of water and nutrients to support its growth for the remainder of the season, and thus it will hopefully have energy for both seed production and to store.
The bulbs need to be planted very deep, ideally 8-12in (20-30cm) depending on their size. They should be left undisturbed for several years, but if you need to lift them to improve the soil conditions or to move them, do so in early autumn, replanting as soon as possible. They may well take a year or two to re-establish.