Large-flowered lilacs

RHS Genus Guide

A mature lilac in full flower is a glorious thing, with great cones of flowers scenting the air in late spring. These larger-flowered kinds are cultivars of the common lilac (S. vulgaris) and its hybrid S. × hyacinthiflora.  Their heyday was in the late nineteenth to mid-twentieth century and some Victorian cultivars such as 'Madame Lemoine' and 'Charles Joly' are still popular today.

Botanical name: Syringa

Common name: lilac

Appearance

Large-flowered lilacs grow into large shrubs or small, multi-stemmed trees, generally 4-6m tall. They have smooth, heart-shaped leaves and generous sprays of flowers, some double, in white, cream, pink, dark red, and all shades of purple. S. vulgaris cultivars generally flower in May;  S. × hyacinthiflora flowers from mid-April, so it can catch late frosts in cold locations.

Preferences

Most lilacs thrive in alkaline soils – those with chalk or limestone underneath – but are tolerant of neutral or slightly acid soils too. They flower best in full sun. Deadheading is worthwhile to avoid resources being used for seed production, and to keep plants looking tidy.

Dislikes

Lilacs don't do well in extremely dry or very wet soil. Growth will be leggy and flowering will be poor in shade. These large-flowered cultivars need room to spread – heavy pruning will spoil the shape and reduce flowering.

Did you know?

Common lilac originates in south-eastern Europe, but the name 'lilac' derives from a Persian word referring to a bluish-violet colour. The large, fragrant flower clusters make impressive cut flowers.

RHS Growing Guide