How to grow lilacs

Lilac blossom is one of the signs that spring is finally giving way to summer and, once those fragrant blooms open, gardens enter a softer phase. The most commonly grown form of lilac is Syringa vulgaris, often called the tree lilac, and these were planted in every British garden in the early years of the 20th century. 

The Edwardians adored lilacs and they were widely used as a cut flower. They did fall from favour in the 1960s, but now more gardeners are planting them once again because few shrubs produce such sumptuous flowers.

The key to getting a good lilac tree is regular pruning after flowering, as plants can become leggy without pruning, and taming an overgrown lilac tree can take several years of careful pruning.

Read our guide to designing and planning a traditional cottage garden

Where to plant lilacs

Forms of Syringa vulgaris are adaptable and long-lived. Lilacs tolerate pollution and seem to thrive in all soils, making them very easy to grow. Smaller varieties can be more fussy but make excellent container plants for a sunny patio.

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How to plant lilacs

Containerised lilacs can be planted in a hole twice the size of the root ball and firmed in with your heel.

Read our guide to planting trees

When to prune lilacs

Tree lilacs do become leggy when left to their own devices, but they respond to regular pruning after flowering. This will keep them compact.

Mature lilacs, even very old ones, can be rejuvenated by pruning.

How to prune lilacs

When pruning a mature lilac that has not been cared for, the technique is to prune back in three stages. Take one third of the bush back hard (after flowering) and then take the next third back in the following year - again after flowering. Finish the remaining third in the next year and you can prune drastically. In the fifth year your lilac flowers will be easily seen in the garden.

If you possibly can, remove the seed heads to prevent unwanted and inferior seedlings. This will also keep the vigour in the plant. It’s particularly important with smaller lilacs as the brown heads produced after flowering are very unsightly.

Read our guide to pruning shrubs

Choosing a lilac variety

Make sure that you have a first-rate lilac plant because grafted lilacs can sucker (given time) and produce plants with very poor flowers. Some of my favourite varieties are...

'Firmament' (1932) AGM
- a shimmering single blue with purple overtones.

'Charles Joly' (1896) AGM
- a double purple.

'Katherine Havemeyer' (1922) AGM
- a double lavender-pink.

More compact lilacs for small gardens

Some lilacs are much more compact and slower-growing and even more fragrant. Their flowers are smaller and more delicate and they make excellent plants for a container or a small garden. These smaller lilacs are fussier about conditions: they prefer well-drained soil and a sunny position.

Syringa pubescens subsp. patula 'Miss Kim' AGM (1954)
'Miss Kim' has slender, pale-lavender flowers in a more open panicle supported by wavy-eged linear leaves. The scent is spicy and the whole plant forms a 2 metre roundel (2 - 2.5 m).

Syringa meyeri 'Palibin' AGM
This form is roughly half the size and rarely reaches above a metre in height. The dark buds open to sweetly fragrant, single-pink flowers and there’s always a two-tone effect because the tube of the flower is darker (1.5 x 1.5 m).

Syringa 'Red Pixie'
Delicate wine-red-buds open to produce pale-pink starry flowers in spring - a completely different colour to others - with dark stems (1.5m).

S. x josiflexa 'Bellicent' AGM
Enormous upright panicles of fragrant purple-pink flowers in June. This could be wall trained because it will reach three metres.

Visit our Small Garden Ideas section for great ideas for limited space

Where to buy

The Gobbett Nursery near Kidderminster are Britain’s leading lilac specialists - www.thegobbettnursery.co.uk

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Did you know…?

Many of those suburban lilacs were bred and named by the Lemoine family who owned a nursery in Nancy in France. The father, Victor, was born in 1823 and died aged 88 in 1911. Victor was a famous plant breeder and he was the first foreigner to be awarded the prestigious RHS Victoria Medal of Honour. He raised the first double potentilla 'Gloire de Nancy' (1854) , the white Japanese anemone'Honorine Jobert' and 'Sarah Bernhardt' (1906) - cited as the most successful peony ever bred. He worked with fuchsias and begonias and also bred Hydrangea paniculata 'Grandiflora' circa 1862.

However Victor Lemoine didn’t begin working on lilacs until he was 47 when he found himself at the heart of the Franco-Prussian War circa 1870. Unable to get away from Nancy (because the French town was occupied by Prussian troops) he looked for a diversion and centred on a double lilac already growing in his garden - Syringa vulgaris 'Azurea Plena'. He began crossing this weedy-flowered 1840s introduction with single forms of S. vulgaris and S. oblata.

As he got older, his chosen lilac got taller and taller and he sent his younger, nimbler and sharper-eyed second wife up the ladder armed with paintbrush, tweezers, a needle and scissors. He steadied the bottom while she collected the pollen-bearing parts from the double flowers. By 1890 he had produced a superb double-white which he thoughtfully named 'Madame Lemoine' and it still remains one of the finest today. In old age he worked with his equally gifted son Émile (1863 - 1943) and in time the grandson Henri (1897 - 1982) took over.

Three hybridising generations of the Lemoine dynasty, all of them long-lived, named 214 cultivars of French tree lilac over 71 years. They came in every shade and flower form between the years of 1876 and 1953. It is said that even today only three are extinct. Without this amazing family there probably wouldn’t be any excellent tree lilacs at all.

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