A French Lilac is a deciduous large shrub, or small tree, growing to about fifteen feet high and is a popular addition to parks and gardens throughout the temperate zone. The flowers are a bright purple and grow in large panicles amid the branches. The term French Lilac is used to refer to modern double-flowered cultivars, or species. This is thanks to the life work of prolific lilac breeder Victor Lemoine. Lilacs are known to flower on old wood (this term refers to whether the plant is pruned, or not. Old wood means the shrub is not cut back each year. New wood signifies that the plant must be pruned to produce blooms.) This means that the gardener must be careful when pruning, lest he discourage the plant from producing flowers.

The French Lilacs in Conservatory Garden are easily the most fragrant of all the spring shrubs, and are considered by many garden visitors to be the highlight of the early summer display. In any case, they certainly make for a hard act to follow.