Lilacs When to sow and plant When to plant lilac
A lilac needs sun to flower well. Plant it between autumn and early spring and it can start to establish before it comes back into leaf.
In short
The RHS says the best time to plant a lilac is from autumn to early spring. Plants in containers can in theory go in at any time, but need more watering if planted in leaf. Choose a sunny, open, uncrowded spot with well-drained, neutral to alkaline soil.
Lilacs: what to do and when
Under cover and outdoors, for UK conditions. The weather differs from year to year and from north to south, so check your local conditions too.
Planting lilac: the dormant season or other times
| Autumn to early spring | Other times (container plants) | |
|---|---|---|
| When | The best time to plant a lilac (RHS lilac guide) | Container plants can, in theory, be planted at any time of year (RHS lilac guide) |
| Plants available | Some mail order suppliers stock a limited range of bare-root plants in the dormant season, from late autumn to late winter (RHS lilac guide) | Plants in pots, from 9 cm up to 12 litres (RHS lilac guide) |
| Watch out for | Ground that is too wet or frozen (RHS shrub planting guide) | More watering if the plant is in leaf (RHS lilac guide). Avoid hot or dry weather (RHS shrub planting guide) |
How to do it
- Choose a sunny, open and uncrowded spot, the RHS says, and make sure it does not become shaded over time, as this stifles flowering.
- Avoid frost pockets: the RHS says late frost can damage both flowers and foliage. If your soil is prone to waterlogging over winter, it suggests mound planting: build a hummock 25–30 cm high and 1 m across and plant into that.
- Plant from autumn to early spring, when the ground is not too wet or frozen. Avoid hot or dry weather.
- Dig a hole to the same depth as the rootball but three times as wide, the RHS shrub planting guide says.
- Set the plant so the first flare of roots sits just below the soil surface. Do not bury the base of the stems.
- Water well, making a puddle that then drains away. Mulch 5–8 cm deep, leaving a 10 cm gap around the base of the stems.
- Water in dry spells for the first year or two. Established lilacs only need watering in exceptionally dry weather.
Common questions
When is the best time to plant lilac?
From autumn to early spring, the RHS says. Its shrub planting guide adds that most shrubs are best planted in that window if the ground is not too wet or frozen.
Can I plant lilac in summer?
A lilac in a container can, in theory, be planted at any time of year, the RHS says, but you will need to pay more attention to watering if it is in leaf. The RHS shrub planting guide says avoid planting in hot or dry weather.
What soil does lilac like?
Well-drained, neutral to alkaline soil, the RHS says. Chalky and limestone soils are alkaline. You can measure your soil pH with a simple testing kit.
Will lilac grow in shade?
The RHS says lilacs need a sunny, open and uncrowded position to flower well, and that shade will stifle flowering.
What do I do with lilac suckers?
Common lilac cultivars tend to send up suckers from the roots. If the plant is on its own roots, the RHS says the suckers will be identical to the parent and can be used to propagate it. Otherwise they are best removed to stop the plant forming a thicket. On grafted plants, suckers will not flower true to the parent and should be removed.
Sources
We wrote this page using the sources below.
- How to grow lilac, Royal Horticultural Society (RHS)
- How to plant a shrub, Royal Horticultural Society (RHS)