Lilac has a reputation for being a big, thuggish shrub that needs the corner of a Victorian garden all to itself. Mostly, that's fair. A common lilac left undisturbed will happily reach four metres or more, and it will sucker into the bargain. But the family is wider than the old purple Syringa vulgaris, and several compact types flower well in a courtyard, a narrow border or even a large pot. Choose the right one, prune it at the right moment, and you can have that unmistakable May scent drifting past the back door without surrendering half the garden to it.
Choosing the right lilac for a small space
This decision matters more than any other. Skip the common lilac unless you genuinely have room for a small tree. Instead, look for these:
- Syringa meyeri 'Palibin' — the dwarf Korean lilac. Roughly 1.2–1.5m after ten years, with smaller leaves, a neat rounded shape and pale mauve-pink flowers a week or two after the common types. It is the best lilac for a pot.
- Syringa pubescens subsp. microphylla 'Superba' — about 1.5m, fine leaves, and it often throws a second, lighter flush of flowers in late summer. Slightly more informal in habit.
- Syringa × persica — the Persian lilac. Around 2m, with narrow, almost ferny foliage and a looser, airier shape. The scent is gentler, so plant it near a seat rather than at the far end of the garden.
- 'Miss Kim' — compact, cool lilac-blue flowers, and good burgundy autumn colour, which most lilacs don't offer.
There are also the reblooming lilacs sold under names such as Bloomerang, which flower again in late summer if you deadhead promptly. They are worth a look, though the second flush is never as generous as the first.
Two things to check before you buy. First, read the eventual height on the label rather than judging the plant in front of you — a healthy young lilac in a two-litre pot tells you nothing about its future. Second, ask whether it is grafted. Many named lilacs are grafted onto common lilac rootstock, and those rootstocks produce vigorous suckers that will eventually swamp the plant you paid for. Suckers have to be pulled off at ground level whenever they appear.
Where to plant: sun, soil and shelter
Lilacs are straightforward once you accept three conditions. They want sun — six hours or more in summer. They want drainage. And they flower best when they are not being blown about.
Plant a lilac in shade and you get a leggy shrub that sulks and produces very few flowers. Plant it in a bog and the roots rot. Most UK soils suit it, including chalky ones, but very acid soil is a problem: lilacs prefer neutral to alkaline conditions, so if your soil is acid, add a handful of garden lime to the planting hole and repeat lightly every couple of years.
A south- or west-facing border is ideal. Give a dwarf lilac about a metre of clearance, and place it where you will walk past it in May — beside a path, a gate or a kitchen window. Scent carries on warm air, and a lilac you never notice is a lilac wasted.
Planting, step by step
- Plant bare-root lilacs between late autumn and early spring. Container-grown plants can go in at almost any time, but avoid frozen ground and the hottest weeks of summer.
- Water the pot thoroughly an hour before planting.
- Dig a hole twice the width of the rootball and the same depth. Fork over the base to loosen it.
- Mix a couple of spadefuls of garden compost into the backfill, plus lime if your soil is acid.
- Set the plant so the soil mark on the stem sits level with the ground. Planting too deep is a common mistake and slows a lilac down badly.
- Backfill, firm gently with your heel — not a stamp — and water well.
- Mulch 5–8cm deep with well-rotted manure or bark, keeping it clear of the stem.
- Water weekly through the first summer. After that, an established lilac mostly looks after itself.
Pruning and year-round care
Get this one rule right and lilacs become easy: they flower on last year's wood, so prune straight after flowering — late June or early July. Prune in winter and you are cutting off next spring's flowers before they have had a chance to form. It is the single most common reason for a lilac that refuses to bloom.
Deadhead the faded trusses back to the first pair of leaves. This tidies the shrub, stops it wasting energy on seed and, in most years, improves the following season's display. Beyond that, little is needed: remove any dead, damaged or crossing stems, and take out one or two of the oldest branches at the base every few years to keep the shrub youthful and open in the middle.
Don't cut hard into thick, old wood. Lilac is not reliable at regrowing from it, and you can end up with a stump and a long wait. Renovate gradually over three or four years instead.
Feeding and watering
Feed lightly in spring with a high-potash fertiliser — a rose feed or diluted tomato feed does the job. Avoid anything high in nitrogen, which gives you leaves at the expense of flowers. Container plants need feeding from spring until midsummer; border plants growing in decent soil rarely need more than an annual mulch.
Growing lilac in a pot
'Palibin' and 'Miss Kim' are the varieties to choose. Use a pot at least 45cm across, filled with John Innes No. 3 mixed with about a fifth horticultural grit for drainage. Stand it in full sun, raised on pot feet so water never sits under it.
Water when the top few centimetres of compost feel dry, and feed with a high-potash liquid feed every fortnight from spring to midsummer. Repot every two or three years, or top-dress annually by scraping off the top 5cm of compost and replacing it. Slightly restricted roots actually encourage flowering, so don't rush to move it into a barrel.
Problems to expect, and what to ignore
Powdery mildew — a white dusting on the leaves in late summer — is the most likely complaint. It is rarely serious. Water and mulch more consistently, and clear fallen leaves, rather than reaching for a spray.
Brown blotches on the leaves in early summer usually mean lilac leaf miner. Cut out the affected growth after flowering and bin the fallen leaves rather than composting them. If shoots blacken and die back, prune below the damage into clean wood.
Finally, a note of patience and a note of caution. A newly planted lilac often takes two to four years to settle and flower properly, and overfeeding it will not speed that up — it will only produce more leaves. And lilac is mildly toxic to cats and dogs if eaten, so if you have a pet that chews shrubs, keep an eye on it and speak to your vet if you are worried.
Making it work in a small garden
Choose a compact variety, plant it in the sunniest spot you have, and deadhead it every July. Those three habits will give you a lilac that flowers generously for decades in a space no bigger than a parking bay. Plant it where you will smell it — near the back door, the bin store you visit daily, or the bench you sit on with a cup of tea. Cut a few stems for indoors when about half the flowers on a truss have opened; the rest will continue to open in the vase, and the shrub will not miss them. Keep the label somewhere safe, too. When you finally decide whether 'Palibin' or 'Miss Kim' suits that corner better, you will want to know what you already have.
Photo: Nowaja / Pixabay
