A perennial is a plant that lives for multiple seasons, while an annual, by comparison, lives out its entire life cycle in a single season.
Planting perennials means that you can look forward to the plant either reshooting such as a daffodil which will sprout up from the same bulb year after year, or to the plant simply continuing to grow larger and flower in season, such as an agapanthus. Agapanthus seldom die back, except in extreme conditions, and will live for a period of three to six years after which they should be divided, cut back and replanted.
Many perennials keep their leaves all year round and form very attractive borders or groundcovers.
When starting perennials from seed, blooms will generally only be observed in the second year of growth, and every year thereafter.
In some colder climates perennials may only last one year, they can therefore be treated as annuals in these climates. These plants remain perennials in terms of their classification.
Plants that re-seed themselves each year, such as marigolds or alyssum, are not perennials. They are simply annuls that drop their seed in late summer and then re-grow from the same seed the following spring.
Popular perennials kept at Windy Willows include Agapanthus, Dietes (wild iris), Star Jasmin, Gazania, Nandina pygmea and plumbago.