Agapanthus are tall with exotic looking flowers in striking shades of blue, mauve, and white. They are are perennial and of the popular varieties offered for sale are some are evergreen and others deciduous. Agapanthus range in height from 10 to 150cm. Growing Agapanthus is easy, getting them to flower is more tricky. The ideal growing conditions are full sun with fertile, moist but well-drained soil and in a sheltered garden. Even though Agapanthus have a single stemmed flower head, they are in flower for a long time.
Agapanthus vary in the extent to which they will tolerate frost and cold, which means for the best results it is important to select the most suitable variety for your garden and to select the right planting place. Like so many of our garden favourites, when growing Agapanthus, the trick is to get the right plant in the right place and this is very much the case with Agapanthus. As a rule of thumb, the deciduous varieties are more hardy than the evergreen varieties, and the less hardy types will need a winter mulch and frost protection.
If your garden is not sheltered, you will need to select a fully hardy variety, which will be described as "H4" which is hardy down to a range of -5-10 and includes varieties such as A. Blue giant, A. Midnight blue, A. Lilliput A, Silver Moon,(as you may expect a short variety up to 10cms) A. Snowy Owl with white flowers. Check when you buy, the label or website will state if the variety is fully frost hardy. Selecting a hardy variety is essential unless your garden is sheltered, or you can bring the plants under glass protection for the winter. For an explanation of "hardy" follow this link
If your garden is exposed, wet, and/or prone to frost, or you wish to grow a more tender variety, Agapanthus are best grown in pots and moved into an unheated conservatory or greenhouse for the winter. Agapanthus are ideal for growing in containers. In colder areas Agapanthus will need shelter and winter protection It can take a little time to get Agapanthus to flower, although once established Agapanthus they will often flower for some years with little trouble. If you live in Cornwall, or the Scilly Isles, you are lucky, and no doubt laughing up your sleeve at this advice, which you can ignore. In these areas Agapanthus grow and flowering abundantly in the milder conditions. ( Which may explain why in New Zealand it's status is of an invasive weed)