What Are Annuals, Biennials and Perennials?

When planning a border you'll have to consider a broad range of plants and will need to know their particular characteristics, planting and growing requirements.

Three types of plant that every gardener should be aware of when creating a colourful and varied border are annuals, biennials and perennials.

Annuals

By definition, an annual plant is grown from seed each year and will then flower, set seed and die during that growing season. They are very useful to introduce colour over a long period of time and are greatly appreciated by pollinating insects.

Annuals are classified as 'half-hardy' or 'hardy' i.e. able to withstand a little frost. They are bought as seed or ready to plant out in trays. There's no need to fertilize the soil, just prepare with added compost to create a light texture, in fact annuals tend to produce more flowers in poorer soil.

Hardy annuals can be either broadcast or sown in drills where they are to grow. This is best done in the autumn in weed free, raked over soil. Some, such as California poppies, might need to be protected by fleece. Alternatively, sow in the spring once the soil temperature goes above 7ºC or they can be sown in a seed tray and then transplanted.

Half-hardy annuals are more challenging to grow as you need a greenhouse, propagator or warm windowsill as they need a temperature of about 18ºC to germinate. Then, after thinning out and transplanting into another tray, they will need to be placed in a cold frame to harden off. Plant out when the threat of frost has passed.

Hardy annuals include Calendula, Cornflowers, Larkspur and Nigella while half-hardy annuals include Cosmos, Lobelia, Nicotiana. Osteospermum and Zinnia.

Biennials

Biennials are sown in one year but flower during the next season. They can be bought as bedding or seeds. The latter are sown during the summer thinly in potting compost. Prick out when the seedlings are large enough to handle and transplant into plugs, then plant out to their final positions in the autumn.

Popular biennial plants include Foxgloves, Honesty, Sweet William and Wallflowers.

Perennials

Perennials continue growing over a number of years or emerge each year, they can be raised from seed, bought as plug plants or in containers from garden centres. Germinate the seed at about 18ºC, transplant the seedlings to a cooler place, then harden off and plant out in early summer. Container grown perennials should be planted in the spring, firmed in and well watered.

There are a huge number of perennials suitable for a variety of soils and climatic conditioners, the most popular include Echinacea, Geraniums, Lavender, Rudbeckia and Cranesbill.