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How to care for a lilac tree – the complete guide
Last Updated on January 21, 2020 by John
Almost everyone is a fan of lilacs, a beautiful shrub complete with canes and flowers coupled with a sweet scent. Moreover, lilacs come in seven different colours of flowers and will bloom steadily for 6 weeks each season. These plants are strong, simple to care for, and low maintenance. They reach varying size based on variety with fragrant blooms that attract butterflies and neighbours alike.
|Sun||Full or partial sun|
|Soil||Any type, with neutral to alkaline soil|
|Flowers||Pink, blue, white, purple|
|Special features||Attracts butterflies|
Planting lilac trees
When you start planting your lilacs, be sure you have fertile, well-drained soil. If the soil you have at home 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.
With your soil all ready, you can choose the location. Pick a place where the lilac will enjoy access to at least 6 hours of sun. When lilacs get insufficient sunlight their blooms are not as impressive and they thrive in more 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 fall if possible, or spring if must. In the autumn they have often stopped growing but the ground is still warm so they will put out some root before winter giving them a better start for 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 nursery 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 meter or two apart depending on the variety as they can grow fairly large and need room too grow.
Once you have planted your lilacs 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 its established, something you will have to be more cognizant of in the summertime. Usually once established they won’t need watering as 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-fertilization or incorrect pruning as they flower on the previous year’s growth. Lilacs do not require a great deal of fertilization 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 all at the same time when tend to form around the base of the plant.
Pruning lilac trees
When it comes time to prune, you need to be aware that lilacs will bloom on old wood which 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 remove the wood on which your flowers bloom or you might remove the newly developing flowers before they had 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 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 as they will not be able to cope with the weight of the flowers.
How to prune large overgrown lilacs
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 the following year remove 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 meters which might sound drastic but rest assured that lilacs are incredibly strong so it will work well without harming the plant but it will take your shrub a few years to come back to flower to its full potential.
Common pests and diseases
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. So can spray for mildew but with larger trees, it can be impractical but can be worth doing on smaller plants.
If you want to improve the flowering, don’t let 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 any other time of year