Lilac Syringa Vulgaris – tree lilac – is a classic garden shrub or small tree, part of the olive family bearing panicles of fragrant, tubular, single or double flowers, in shades of purple, pink and white, from late spring-early summer.
Flowers are excellent for cutting, edible too, with many cultivars to choose from, some compact and suitable for smaller gardens or pots, while larger types can be grown as a standalone specimen.
Easy to grow, Lilacs can grow around 30-60cm in a year, thriving in moist well-draining soil in a sunny position, given an annual mulch in spring.
As the flowers fade towards mid-summer, dead-head spent blooms on smaller shrubs. Prune shrubs to desired height and shape, after flowering, to prevent from getting leggy and dead, diseased or dying wood.
Lilacs respond well to hard pruning and you can cut the whole plant back to around 1m above ground, as they flower on the previous year’s wood, but you will lose the flowers for at least a year.
Alternatively, remove some stems, over a period of two or three years, cutting back to the ground, ensuring you still enjoy some spring flowers.
Propagate lilacs from softwood cuttings or from suckers, that often sprout from the base. Dig them up with some roots attached and re-plant.
Lilacs are generally problem free, but may be attacked by lilac leaf mining moths or thrips and Lilac blight.
Pruning out affected branches, well beyond signs of infection, in dry sunny weather, may help, improving air circulation, helping to control spreading.
Poor flowering in spring could be due to poorly drained soil, or not enough. Late frosts can also spoil flowers.