Crocosmia plants have long blade-like green leaves like irises and produce tall stalks bearing numerous brightly coloured yellow, orange or red flowers. As they are native to southern Africa, the plant needs direct sun and humus-rich soil to grow well in the UK. Crocosmia can be propagated via dividing clumps of corms formed at the root base, but a home gardener can also start them as seeds for the sake of economy.
Crocosmia seeds are formed in pods made from the spent flowers once they've been pollinated. The flowers can be pollinated by insects, but hummingbirds also favour the funnel-shaped flowers. You can find them by the fact that the pods will be dry and coffee-coloured and may be open to reveal fleshy fruits resembling berries inside. The seeds are inside the fruit of the plant, and should be gathered before they split and spill. The seeds themselves are round like stones and dark in colour.
According to Ken Druse of "Making More Plants," crocosmia seeds can be started indoors six to eight weeks before an area will have its last frost. July is a good month in the UK for the plant and it will thrive in periods of heavy rain. The seedlings can be transplanted outdoors after the last threat of frost. It will take the seedlings up to 90 days to germinate.
Make sure you buy a variety of crocsmia that has been naturalised to the UK. Any plant you buy in a British garden centre will thrive anywhere in the country as long as it is given strong sunlight. Growing from seed may be too labour-intensive for people who grow them as annuals because they will not be able to reap the benefits of having them return year after year.
According to website The Crocrosmia Gardens there are eight known species of crocosmia. Due to the existence of hybrid forms, it may not be possible to guess what an adult plant will look like based on the seed; the offspring may revert to the appearance of an ancestor plant instead of the hybrid form.
Plants grown from seed, including crocosmia, may not flower the first year they are planted. During the first year, the plant will grow leaves and build a corm: a root that stores energy for future blooms. The plant may flower the second year depending on how large the corm has grown.