How to Plant, Grow, and Care For Lilacs in Your Garden
Are you planning on growing lilacs this season, but aren't quite sure where to start? Lilacs are a popular shrub that can survive and thrive in many different hardiness zones. In this article, certified master gardener Liz Jaros walks through how to plant, grow, and care for Lilacs in your garden space.
With a sweet, intoxicating scent that triggers nostalgia for a simpler time, lilacs occupy a special place in most of our hearts. One whiff takes us right back to childhood, running wild through the neighborhood on a warm spring day. The sun is out. Winter is behind us. Life is good.
So it’s no wonder many of us reach for this classic landscape staple to fill our yards with some familiar and reliable garden joy. Most likely, the mere mention of lilacs conjures images of the rambling, unruly purple flowering shrubs we remember from the good old days, but the genus actually boasts 25+ species and thousands of delightful cultivars.
Lilacs require plenty of sunshine, well drained soil, and proper airflow if they are to produce healthy, plentiful blooms year after year. Let’s take a closer look at the history of this popular perennial shrub, as well as their growing requirements, varieties, uses, and maintenance requirements.
Lilac Plant Overview
Plant Type Shrub, tree
Family Olive (Oleaceae)
Species Syringa spp.
Native Area Eastern Europe, Asia
Hardiness Zone USDA 3-7
Season Early spring – early summer
Exposure Full Sun
Plant Spacing Variety dependent
Planting Depth Variety dependent
Height 3 feet to 30 feet
Watering Needs Even, moderate
Pests Lilac borer, leaf miner, scales
Disease Powdery mildew, blight, leaf spot
Soil Type Loose, well-drained
Plant With Spring bulbs, peonies, clematis
Attracts Bees, Butterflies
Ranging in height from 3-foot ornamental shrubs to 30-foot trees, lilac varieties are diverse in stature and personality. The International Lilac Society recognizes white, violet, blue, lilac, pink, magenta, and purple as the official color classifications for lilac blooms. Lilacs require at least some winter dormancy for flower production, making them hardy in zones 3-7.
Most lilac species have roots in Asia, but the oldest known species is Syringa vulgaris (common lilac), a member of the olive family (Oleaceae). This particular lilac dates back to 15 century Europe, where it grew in rocky landscapes on the Balkan peninsula.
The word Syringa is derived from the Greek word syrinx, which means pipe or tube, because a lilac’s sturdy stems could be hollowed out and used for utilitarian purposes. The word lilac is rooted in the Persian/Arabic words for ‘blueish.’
Lilacs were brought to North America in the 17th century, where they were grown heavily in colonial landscapes and grew quickly in favor with the founding fathers. Both George Washington and Thomas Jefferson are said to have featured lilacs in their formal gardens.
Cultivation & Classification
Throughout the centuries, botanists have experimented with scent, flower color, bloom time, and growth habit to cultivate thousands of new lilac varieties. The distinctions are often so small that it can be difficult for even seasoned professionals to tell them apart, but most cultivars are sorted into flowering shrub, hedge, or tree form and originate from the following mother species:
Common or French (Syringa vulgaris)
This is the lilac species that typically comes to mind for all of us. A fast growing shrub with a wild habit that can reach heights and widths of 20 feet if left unchecked, common lilacs typically feature smooth, heart shaped leaves and traditional, cone-shaped blooms that are very fragrant. Common Lilac is planted as a shrub that flowers in white, and all shades of purple.
Littleleaf (Syringa microphylla)
This small, round ornamental shrub comes in sizes that do not exceed 5 feet. It features small, fragrant, late blooming flowers and makes a nice accent plant.
Persian (Syringa persica)
Growing 3-4 feet tall and 8-10 feet wide, persian lilacs feature tight branching and a more compact habit. Flowers are small and pale in color, and leaves are narrow. It takes shearing well and is commonly used as a low hedge.
Chinese (Syringa chinensis)
A cross between the Persian and common lilac, this hybrid features classic bloom sizes on an 8-12 foot tall hedge. Foliage is small and similar to Persian, which makes it easy to shape. Blooms are more prolific than both of its parent species.
Tree (Syringa reticulata)
Large clusters of creamy to white flowers explode in early summer on most tree form lilacs, emitting an odor that many find unpleasant. The leaves are oval and shiny. Trees may be single or multi-stemmed and max out at 30 feet in height.
Most lilac varieties are prolific and fast-growing when given the right conditions. While this makes them borderline invasive in some settings, it also makes them one of the easiest flowering shrubs to propagate.
Lilacs can be propagated effectively from suckers (root sprouts), layerings, cuttings, and bud grafts. Since nearly all lilacs are hybrids and will not reproduce true to seed, propagation from seed is not recommended. Let’s look at the steps involved in sucker harvesting, layering, and cutting since they are the most foolproof techniques for novices.
Propagating Lilacs from Root Sprouts
Like many other clump-form trees and shrubs, lilacs will send new branches out from its roots. When these ‘runners’ breach the soil surface, they are typically removed to encourage the development of a small number of large branches rather than a large number of small ones. The former will yield a stronger, more attractive lilac specimen.
But sucker removal can be a great way to reproduce lilacs, and it is perhaps the easiest method for newbie gardeners. Typically undertaken in spring or fall when temps are cool and root growth is strongest, here’s how lilac sucker propagation is done:
Sucker Propagation Steps
- Dig down around the sucker to the point where it attaches to your lilac’s roots.
- Make a sharp pruning cut as close to the mother plant.
- Remove the running branch.
- Be sure to include any feeder roots that may have sprouted from it below the surface.
- Plant the sucker 6-8 inches deep in a pot with potting mix or directly in the ground.
- Keep your new lilac moist but not wet, and make sure it gets plenty of sun.
- It’ll likely be a couple of years before you see any real growth or blooms, so be patient!
**Pro Tip: Make sure the lilac you’re working with is not grafted. Sometimes growers will splice lilac cuttings onto established root stock during nursery propagation. If there is a knot or a thick ring at the base of its trunk and an obvious distinction between above and below ground growth, the sucker is probably coming from mystery stock and your new lilac will not be a clone.
How to Propagate Lilacs from Layering
This technique also takes time, but it’s easy to do and will yield great results. Even from grafted stock. The process involves bending a healthy lilac branch down toward the ground and essentially pinning it in the dirt until it sets roots. Here’s how it’s done:
Layer Propagation Steps
- In spring, find a lilac branch that is long, slender, and flexible.
- Shoot for something roughly the width of a pencil.
- Work some sand and/or peat moss into the soil below the branch.
- This will help the soil will drain well around your transplant.
- Make a two-inch notch or scrape off some bark on the top side of the branch.
- This will be, about one foot down from the tip.
- Dust the wound with some rooting compound
- Bend the branch down into the dirt and hold it in place with a wicket, or stake.
- Pack 3-4 inches of newly amended dirt over the wounded section.
- Top with mulch or hay.
- Water regularly to keep the area moist, but not soggy.
- When roots have developed sever the branch from the parent lilac with a sharp cut.
- Leave it in place for three weeks to let it recover from the shock.
- Unearth the sunken branch, being careful to preserve the roots.
- Transplant to your desired location.
- Be patient and your shrub will fill in over the years.
How to Propagate Lilacs from Cutting
Just as it sounds, propagating lilacs from cutting involves pruning a small section of lilac branch from an established shrub and turning it into a new plant. This is how you do it:
Cutting Propagation Steps
- In late spring or early summer, look for new growth at the tip of lilac branches.
- It will be soft and green, not brown and hard.
- Cut a piece that is 4-6 inches long and has some leaves.
- Strip off lower leaves but allow 2 or 3 to remain near the tip.
- Dip the cut end in root hormone.
- Insert the cut end into a container filled with potting mix.
- Keep soil moist but not wet, and check for roots after 2-3 months.
- Transplant to desired location in fall or spring, when temps are cool.
If you’re looking to introduce some new lilac varieties to your landscape and/or make an impact right away, you’ll likely be purchasing an established lilac from a nursery or garden center.
Do not go shopping until you’ve determined that you have the ideal planting location (sunny with well-drained soil and good air flow) and know exactly what size you want (a small accent shrub near the patio? A tall hedge to screen the neighbors? A major tree in the corner? Next to other great lilac companion plants in your garden? ). This will help you identify which cultivars to focus on.
Once you’ve honed in on a variety that suits your fancy, you’ll likely be looking at a whole row or section of them, and you’ll have to choose which one(s) to bring home.
Lilacs are typically sold in #5, #10, or #25 containers (the size corresponds roughly but not exactly to the number of gallons each container holds) or as balled and burlapped field grown plants. Let’s take a closer look at each option and talk about how to plant them.
Planting Container Grown Lilacs
Generally speaking, small containers will hold younger plants and larger containers will hold slightly older plants. When selecting a lilac grown in a container:
- Look to make sure roots are not growing out of the bottom.
- Examine the stem or stems to look for even, upright growth and equal girth.
- Examine leaves to ensure they’re healthy and disease free.
Container grown lilacs should be planted in fall or spring, when roots will have time to establish without stress from extreme heat or cold. Lilacs should be planted in a hole just as deep and twice as wide as the container in which they were grown. Make sure the top of their roots sit slightly higher than soil level.
Planting Ball & Burlap Lilacs
Field grown lilacs will be more established than container grown plants, and are the best choice for instant gratification. Depending on the nursery, they may be sold according to their current height (6’, 7’, etc.) or by caliper, which is essentially the width of their trunk (1”, 2”, etc.).
Whichever you choose, it will be heavy and you will likely need a little help getting it in the ground. The selection instructions are similar to container-grown lilacs, but the planting instructions require a few extra steps:
Ball & Burlap Planting Steps
- Determine if your root ball is wrapped in natural or synthetic material.
- If you don’t know for sure, run a lighter through a small section of it.
- Natural burlap will turn to ash immediately, while synthetic will smoke and/or melt.
- If roots are wrapped in synthetic material, remove it entirely.
- Synthetic wraps will not break down in the soil.
- If burlap is natural, leave in place but peel back the uppermost section.
- This will allow for proper drainage and root growth.
- If your lilac’s roots are enclosed in a wire cage, it can remain in place while planting.
- Make sure you’ve exposed the top 12 inches of your root ball.
- Plant in a hole that is just as deep and 2-3 times as wide as your root ball.
- Make sure the top of your root ball sits a couple of inches above soil level.
How to Grow
Known for being hardy and low maintenance, lilacs are fairly easy to grow as long as their basic needs are met. Let’s look at the requirements and practices that will provide your lilacs with the best possible start and the most favorable conditions for a long, healthy life.
Lilacs require at least 6 hours of sun and will thrive when they don’t get too much afternoon sun. While they will survive in a slightly shady spot, they will not flower well or grow as quickly. They will also be more vulnerable to shade-related conditions such as powdery mildew. There are also varieties that can handle more than 6 hours of sun, provided it’s not too hot in the afternoons.
While lilacs will require regular, even watering during their first year, they rarely need supplemental watering in subsequent years. Give them a deep, slow soaking once a week in spring and twice a week in summer for best results. As they do not like wet feet, make sure drainage is good and soil never puddles.
Lilacs are fairly adaptable, but will thrive in rich, well-drained soil. Before planting, amend soil with compost or humus to increase organic content, and work in some peat or sand if soil tends toward clay. Be sure to choose a site that will not get standing water.
Lilacs prefer neutral to slightly alkaline soil. If you don’t already know your soil’s pH, you may want to have it tested. Shoot for a level somewhere between 6.5 and 7. If pH is too low, add a little lime to increase acidity. If it’s too high, work some sulfate or bone meal into the dirt.
Lilacs should always be planted with their root flares sitting slightly above soil level. The root flare is the point at which underground roots breach the soil surface and narrow into a trunk or clump of trunks. Sitting the flare above soil level will ensure that roots are never flooded or submerged in water.
Lilacs are typically spaced between 5 and 15 feet apart. This means 5 feet from trunk to trunk, not from the edge of the plant or the edge of the hole. Check your cultivar’s growing requirements and follow their space requirements carefully. Lilacs do not like to be crowded and need proper air circulation for healthy growth.
Climate & Temperature
Lilacs require a dormant period in order to flower, so they grow best in climates that have a true winter. Tolerant of extreme temperatures, they do not typically need protection from deep freezes, unless they are exposed to high lake winds or something out of the ordinary.
Considered hardy in zones 3-7 with a few varieties that are hardy to zone 8, lilacs do not grow well in warmer southern regions where the heat is intense. And they do not like humidity, since they are prone to fungal conditions.
Lilacs do not need a lot of supplemental fertilizing in order to bloom beautifully. And they should not be fertilized with a mix high in nitrogen if abundant flowers are the objective. Nitrogen will give you lots of leaves and stem growth, but fewer blooms.
If you feel they need a boost, wait until their second year of growth and hit them with a 5-10-5 fertilizer in early spring. Repeat every year or every other year as needed but don’t overdo it.
Maintenance & Care
Lilacs are known for being pretty laid back, but they do require some regular maintenance if they are to keep blooming year after year. While they may not be as high maintenance as hydrangeas, you’ll still want to practice regular pruning, mulching, and deadheading.
By far the most important maintenance task, lilac pruning must be done immediately after lilacs are done flowering for the season. As next year’s buds form on this year’s growth, the timing of this is crucial if you have high expectations for next season’s blooms. Here’s how it’s done:
Routine Pruning Steps
- Evaluate your lilac’s size and determine if it needs to be scaled back.
- Older, more established varieties might be outgrowing their available space.
- If height or width is an issue, begin by taking off roughly ⅓ of your lilac’s branches.
- Use a lopper or hand saw.
- Start with branches that are crossing, oddly shaped, or low hanging.
- ALWAYS make these first cuts at the plant base.
- Remove all suckers that have erupted from the dirt around your lilac.
- Do this by digging down and cutting them as close to the root base as possible.
- Remove all wood that appears gray, hollow, or dead in the same manner.
- Reduce height by clipping tall canes down to roughly eye level.
- Look for a spot just above a node or set of leaves and make cuts there.
- Do not cut all canes at the same height.
- Aim for a rounded form that features longer canes in the shrub’s middle.
**Pro tip: If lilacs are newly established or size is not an issue, perform the deadwood, crossing branch, and sucker prunes only and remove all spent blooms at a leaf set just below their stems.
If you’re working with lilacs that are severely overgrown or out of control, consider giving them a major haircut to encourage a more manageable plant. Lilacs can be cut down to 6-12 inches above ground level, and they will almost certainly grow back in better form!
Renewal prunes should be done in late winter or early spring, during dormancy. This timing will reduce the odds of stress, disease, and pest infestation. Bloom time is not an issue because renewed lilacs will not flower for another couple of years. But when they do, it’ll be worth the wait!
Keep the area around their trunks tidy and free from grass and weeds, and maintain a 2-3 inch layer of organic mulch beneath their canopies. Bark and wood chip mulches work well under large shrubs and hedges, but make sure it’s pulled slightly away from the plant base and never touches the root flare.
Since the ideal pruning time for lilacs is immediately after they are done blooming, many cultivars will not need to be deadheaded. The exception is reblooming varieties such as Syringa ‘Josee’ and ‘Bloomerang.’ These lilacs are designed to flower again during the season if properly cared for.
This means you’ll want to regularly keep up with deadheading, or their blooms will start to suffer. Many novice lilac gardeners seem to fall into this trap when they pick a variety they aren’t familiar with.
For these varieties, prune off spent blooms with a sharp cut just above the first set of leaves you encounter as you slide your fingers down their stems. This will encourage your lilac’s roots to send up new buds for a second bloom in mid-summer. Some cultivars will even send up a third bloom in late summer.
While most lilac species and cultivars share similar characteristics (large fragrant blooms, early season color, sun loving, etc.), each comes with its own unique personality.
Most are flexible and can be employed in a group or a solo planting, and most take shaping well to suit multiple purposes. Here’s a look at some delightful, but tried and true lilacs you may want to consider working into your landscape.
Syringa vulgaris ‘Charles Joly’
A descendant of the common lilac, Charles Joly has fragrant, double flower panicles in rich, grape hues. Blooming for up to four weeks and reaching heights of 10-12 feet, this vase-shaped shrub is a lilac lover’s darling.
Syringa pubescens var. patula ‘Miss Kim’
Maxing out at 5 feet, Miss Kim is an early spring bloomer and a butterfly magnet. A dwarf derived from the Korean lilac lineage, this one has rounded, dark green foliage that turns burgundy in fall. It can be planted as a stand-alone garden accent or grouped and shaped into a mini hedge.
Syringa x chinensis ‘Sunday’
With a graceful, arching habit and huge purple flower clusters, Sunday works well near a fence or arbor. It blooms in early spring, reaching heights of 10 feet and widths of 8 feet at maturity. As a cross between hedge and shrub lilacs, Sunday takes shape very well but still pours on the classic lilac charm.
Syringa x prestoniae ‘Miss Canada’
With cheerful pink blossoms that emit a strong, sweet scent in early summer, Miss Canada grows 6-9 feet tall and wide. An early summer bloomer, this shrub steals the show in fall, when its leaves turn a rich yellow color.
Syringa x SMSXPM ‘Scents and Sensibility Pink’
This dwarf, compact shrub is covered almost completely with pink flower clusters in early spring. Maxing out at 3 feet round, Scents and Sensibility Pink is also a rebloomer. Shear back after each bloom period and flowers will keep coming all summer long.
Syringa reticulata ‘Ivory Silk’
Growing 20-30 feet tall with a spread of 25 feet, Ivory Silk has a graceful, oval shape. Creamy, 10-inch white panicles grow prolifically and emit a pungent odor for 1-2 weeks in early summer.
Syringa x josiflexa ‘Royalty’
At 8-10 feet tall and wide, Royalty makes a great privacy screen. Dark purple buds open to shades of lavender in early summer, making this one of the later flowering varieties. Dense, dark foliage takes pruning well and grows quickly.
Some lilac species feature tight branching habits and small leaf sizes, which makes them ideal for hedges. Anything in the persian lilac family can be sheared into a formal border plant for your patio or walkway, but they will not be tall enough to provide much privacy.
Common lilac varieties work well as privacy screens. They are looser in form and give off a more natural vibe but tall enough to create a visual barrier. When planted in a row, they will eventually grow together like a living fence.
Little leaf lilac hybrids are typically prized for their dense profusion of blooms and incorporated into the landscape as dwarf, flowering shrubs. They might be featured singularly, in a group, or in a row.
Lilac trees can be used as shade trees or anchor plantings and are typically not planted in groups or rows. They are stand-alone ornamentals valued for their blooms and mid-sized form.
Lilac blooms were originally harvested for medicinal purposes and used in elixirs and potions. Their scent is heavily featured in soaps, perfumes and air fresheners.
Lilac blooms are completely edible, but not super tasty. We often see them in food and drinks because they pack a punch of color, but their bitterness is typically masked by some kind of sugar or salt. Lilac blooms also make wonderful cut flowers, but they will only last a few days inside.
Lilacs are strong, resilient, and resistant to most insects. But, like with all plants, there are certain pests that you’ll need to watch out for. Lilac pests can be stopped or controlled if you catch them early, and act swiftly. Let’s look at the most common pests you’ll deal with.
This is the most common lilac aggressor and is typically found on older branches first. Adult borers are wasp-like moths with clear wings and red heads, while larvae are white-pink caterpillars with red-brown heads.
Look for cracked bark, broken branches, and/or stem holes that may exude sap or a sawdust-like excrement to indicate lilac borer infestation.
If borers are caught early, they can be effectively managed by pruning off limbs that are being attacked, so careful monitoring is key to addressing this pest. Just know that recovering lilacs may need extra watering and attention for a while.
If a large mass or span of lilacs are being bored and you feel like you’re enduring a major attack, a pyrethroid or bark spray application in fall might help eradicate their larvae and discourage an infestation next season.
Most of this pest’s damage is done by its larvae, which are small, white, and less than ¼ inch long. Yellow, squiggly lines (or mines) on your lilac’s leaves will show you where they have been boring through the tissue. Later in the season, a rolled leaf may indicate that caterpillars are pupating.
While not usually lethal, miner damage can be unsightly and should be dealt with before it gets too severe. Prune off leaves that have mines or pupae, and monitor carefully. Keep the areas beneath your lilacs free from leaf debri to reduce leafminer habitats.
These small, shelled insects are about 1/16th inch long and look like tiny gray or brown warts. They typically suck sap from a lilac’s stem, which may weaken them and make them prone to breakage. Not usually a major threat if caught early, scales can be effectively managed with spot pruning and horticultural oils.
Again, lilacs are typically disease resistant if planted and cared for properly. But, there are a few diseases that are more commonly seen. If caught early, most can be treated. If not, it can cause discoloration of your plant, or even plant death, so early intervention is key.
By far the most common lilac affliction, powdery mildew presents with white, chalky leaf splotches that turn gray or black later in the season. Typically, your first signs of it will appear on lower leaves in times of high humidity and moisture.
The good news is, powdery mildew is more of an aesthetic issue than a health issue, and your lilacs should fully recover by the following season. Cut off affected leaves, or ignore them completely until the flowering season is over, then give your lilac a good prune.
Thin your lilac’s base to encourage good air circulation. Promptly remove fallen leaves and branches, as mildew can overwinter in the soil and show up next year.
Some lilac cultivars claim to be resistant to powdery mildew. Consider ‘Charles Joly,’ ‘Sensation,’ or ‘Old Glory’ for the landscape if you’d like to discourage the disease from spreading in your yard.
Another moisture-related lilac disease, bacterial blight presents with brown-black leaves, distorted shoots, and sickly flowers. You might see yellow halos on your leaves or blackening flower buds if you catch it early enough.
Caused by bacteria that is always present on lilac leaves but flourishes when they’re wet, blight makes lilacs more prone to damage from the cold. Again, aggressive pruning and seasonal bed cleanup are key to management, as is proper watering to reduce moisture on the leaves.
Septoria Leaf Spot
This fungus presents with dramatic browning of the leaves at your lilac’s base and works its way up. It typically afflicts plants during seasons that have excessive amounts of rain.
On branches with symptomatic leaves, you will see healthy buds for next year’s growth when leaf spot is the culprit. Leaves may be pruned off and buds left in place. Again, be aggressive with the post-bloom pruning and cleanup, and this disease will not pose a long term threat.
Frequently Asked Questions
Can lilacs grow in pots?
Yes, but only if you choose a dwarf variety and a container that can accommodate a lilac’s oversized root system.
Are lilacs invasive?
No, lilacs have an aggressive growth habit but they do not spread or cause damage when planted and pruned properly.
Can lilacs grow in hot and humid locations?
No, anything above hardiness zone 7 typically will be too hot and humid for lilacs to perform at their best.
Ushering in a new season of backyard burgers and walks in the park, lilacs open a magical door for most of us. Walk through and you’ll be treated to a multi-sensory experience like no other. Invite some lilacs into your landscape, care for them properly, and enjoy the show year after year.