General gardening topics

How to care for a lilac tree – the complete guide

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Almost everyone is a fan of lilacs, a beautiful shrub complete with canes and flowers coupled with a sweet scent. Moreover, lilac flowers come in seven different colours and will bloom steadily for six weeks each season. These plants are strong, simple to care for and low maintenance. They reach varying sizes based on the variety and their gorgeous fragrant blooms attract butterflies and neighbours alike.

Botanical NameSyringa
SunFull or partial sun
Soil Any type, with neutral to alkaline soil
Bloom timeSpring/Summer
FlowersPink, blue, white, purple
Special featuresAttracts butterflies

Planting lilac trees

When you start planting your lilacs, be sure you have fertile, well-drained soil. If the soil you have in your garden is poor in nutrients or density, you can add compost to enrich it before planting. If possible, keep the pH levels around neutral or slightly alkaline; you can test this level with a simple at-home test kit. If you have a good variety of plants already in your garden then it will probably be fine for growing a lilac tree.

Lilac tree growing well in my garden

With your soil all ready, you can choose the location. Pick a place where the lilac will enjoy access to at least six hours of sun. When lilacs get insufficient sunlight their blooms are not as impressive and they thrive more when planted in the sun.

The soil needs to be well-draining. Lilacs will not bloom if the soil has too much water. Once you are ready to plant, do it in the autumn if possible, or spring if a must. In the autumn they have often stopped growing but the ground is still warm so they will put out some roots before winter giving them a better start the following spring.

If you are planting a potted lilac tree from a nursery, spread out the roots as you settle the Lilac into the hole you dig but don’t disturb the roots too much. If the roots have become balled up or they are inside of a burlap sack, simply remove the covering and any rope around it before you plant. Then place the plant approximately 60cm deeper than where it was in the pot and put some topsoil around it, particularly around the roots.

Once your lilac is settled make sure to water it and then complete it with some topsoil. If you have more than one lilac bush that you are planting at once, space them out a metre or two apart depending on the variety because they can grow fairly large and need room to grow.

Lilac care

Once you have planted your lilac, caring for them is quite simple. Every spring you just need to add a layer of compost to your plant and then throw some mulch in there to help it retain moisture. Adding the mulch in tandem with the compost will better control the weeds as well.

After you have planted your lilac tree you will need to keep it watered until it’s established, something you will have to be more observant of in the summertime. Usually once established they won’t need watering because they have a good deep root system and can usually get all the water they need themselves.

If your lilac is not blooming it might be indicative of over-fertilisation or incorrect pruning because they flower on the previous year’s growth. Lilacs do not require a great deal of fertilisation and will typically only tolerate a 10-10-10 handful at the end of winter. After the Lilac has finished blooming you can put some manure and lime around the base if you want, trim the bush to create the shape that you desire and get rid of any suckers that tend to form around the base of the plant.

Pruning lilac trees

Pruning lilac trees which flower on old wood

When it comes time to prune, you need to be aware that lilacs will bloom on old wood and this means the wood from the previous season so it’s critical that you only prune in the springtime right after they have bloomed.

If you do it before that, or you do it later in the summer, you might end up removing the wood on which your flowers bloom or you might remove the newly developing flowers before they have a chance to bloom. This is probably the most common reason for lilac trees not flowering. So as soon as it’s flowered, just give it a prune to keep it to your desired shape and size.

Each year after your flowers have bloomed you can get rid of any dead or diseased wood. You can also prune out any of the oldest canes all the way down to the base, get rid of suckers and cut back any branches that are very weak because they will not be able to cope with the weight of the flowers.

How to prune large overgrown lilacs

Hard pruning lilac tree which will recover but may take 2 years to flower again

If your lilac is very old and mature, you can revive it by removing one-third of the oldest branches all the way down to the ground, with the following year removing half of the remaining old branches, and the third year remove the remaining old branches. This type of rejuvenation is something you can do with mature plants. With very mature plants you can also just chop the entire plant down to about 1 to 2 metres, which might sound drastic, but rest assured that lilacs are incredibly strong so it will work well without harming the plant. However, it will take your shrub a few years to come back to flowering at its full potential.

Common pests and diseases

Lilac with mildew, remove worst effect leaves and spray with a fungicide
Lilac with mildew, remove worst affected leaves and spray with a fungicide

Lilacs are prone to issues with slugs and snails in particular so keep your eyes peeled. In terms of diseases, white powdery mildew might show up on your lilac, especially if you have had a hot and humid summer.

This is typically not harmful it’s just unsightly. You can purchase a spray for mildew, however, with larger trees, it can be impractical but is well worth doing on smaller plants.


If you want to improve the flowering, don’t let the grass grow near your lilac. Instead, cover the immediate area around the base with things like bark or stone. Only prune immediately after flowering and never at any other time of year.

Welcome to my site, my name is John and I have been lucky enough to work in horticultural nurseries for over 15 years in the UK. As the founder and editor as well as researcher, I have a City & Guilds Horticultural Qualifications which I proudly display on our About us page. I now work full time on this website where I review the very best gardening products and tools and write reliable gardening guides. Behind this site is an actual real person who has worked and has experience with the types of products we review as well as years of knowledge on the topics we cover from actual experience. You can reach out to me at

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