Proven to be reasonable hardy and needs protection from only the most server conditions.

Semi-evergreen bulbous perennial

Agapanthus (Liliaceae) the African Lily, a useful plant for the garden, the species that are mostly grown in the UK are generally tough although some are a bit tender, as a loose rule the narrower leaved varieties are much tougher, they generally behave more like herbaceous perennials, loosing their leaves over winter and dying back to a root system. The larger leaved varieties tend to keep their large, strap like leaves over winter and these should be protected from frost or are more suited to coastal areas. 

Soils are not too much of a consideration as Agapanthus will grow in any soil type, what is needed is a good situation, good light is essential as most varieties will lean quite heavily toward the light, the soil should be moist as well, not dry or boggy. They are not generally too hungry but respond quite well to a feed from late spring up to flowering. 

Flowering can be improved by restricting the root, this is one plant that responds well to being root bound so if growing in a pot do not be too concerned if the plant is pot bound with roots showing on the surface, keep pots dry over winter (not too dry) and then in spring, once you see active growth, keep the plants watered and feed plants weekly, this will encourage healthy leaves and flower buds.   

Flowering is between June-September, the flower heads are usually rounded with a slight umbrella shape to them, colours range from white to light blue - dark blue and into purple. Once flowers have gone over the seeds will develop in their place, these are hard, large black seeds. To prolong flowering trim the flowering stems back to the foliage once they have gone over.