Cosmos for quick summer colour
Flowers that germinate, grow and flower in one growing season are called annuals. Some of these tolerate frost and they can be sown outdoors – these are hardy annuals. Annuals that cannot tolerate frost must be sown indoors and planted out when the danger of frost has passed – these are half-hardy bedding annuals.
Some of the flowers used for bedding, such as bedding busy lizzies, bedding begonias and bedding geraniums, are actually short-lived perennials but they are treated as annuals, raised from seed each year and discarded at the end of the season. Some flowers, such as wallflowers, bachelors buttons and pansies, are sown in one growing season and flower the following year.
Plants that flower each year, and then die down over winter are called perennial flowers. The taller types – from 30 centimetres to 300 centimetres – are used as border perennial flowers. Those that grow to less than about 30 centimetres are used as rock garden or front of border perennials.
Bulbous flowers with bulbs, tubers or corms, are a special category of perennial flowers, and deserve special mention.