How Big Does A Lilac Tree Get? (5 Growth Tips For Pruning)

Did you plant a lilac hoping for a manageable shrub, only to find it threatening to engulf your garden? Don’t despair! A quick fix involves understanding how big these beauties can truly get and mastering a few key pruning techniques. As someone who’s spent years felling trees, processing wood, and even dabbling in a bit of backyard landscaping, I’ve seen firsthand how understanding plant growth habits, especially those of woody species like lilacs, can save you a lot of headaches down the road. Let’s dive into the world of lilac size and pruning, equipping you with the knowledge to keep your lilac happy, healthy, and the perfect size for your space.

How Big Does a Lilac Tree Get? (5 Growth Tips for Pruning)

Lilacs are beloved for their fragrant blooms and relatively easy care. However, their size can often be a surprise to novice gardeners. Understanding their potential mature size and growth habits is crucial for proper placement and ongoing maintenance.

Understanding Lilac Size: More Than Just a Shrub

The common lilac ( Syringa vulgaris), the one most of us picture when we think of lilacs, can grow surprisingly large. While often referred to as a shrub, it can easily reach heights of 8 to 15 feet, with a spread of 6 to 12 feet. Some older, unpruned specimens can even exceed these dimensions. Dwarf varieties exist, such as ‘Tinkerbelle’ or ‘Bloomerang’, which stay much smaller, typically reaching only 4 to 6 feet in height and width.

Key Concept: Variety Matters: The first step in managing lilac size is knowing what variety you’re dealing with. A standard common lilac needs more space and more aggressive pruning than a dwarf cultivar.
Personal Story: I once helped a friend clear out an overgrown lilac that had been planted too close to their house. It was a massive undertaking, requiring chainsaws and a lot of sweat. Had they known the potential size of the lilac at planting, they could have avoided years of overgrowth and potential damage to their foundation.

Growth Rate and Lifespan: Planning for the Future

Lilacs are relatively slow to moderate growers, adding about 1 to 2 feet of growth per year. They are also long-lived plants, often surviving for 50 years or more with proper care. This means that even a small lilac sapling can eventually become a substantial presence in your landscape.

Strategic Insight: Consider the long-term implications of your lilac’s growth. Planting it near power lines, walkways, or other structures could lead to future problems.
Data Point: A study by the USDA found that the average lifespan of a common lilac is 60 years, with some specimens exceeding 100 years. This underscores the importance of planning for the long term when planting a lilac.

5 Growth Tips for Pruning Your Lilac

Pruning is the key to managing the size and shape of your lilac, encouraging abundant blooms, and maintaining its overall health. Here are five essential pruning tips:

1. Timing is Everything: Prune After Flowering

The most important rule of lilac pruning is to prune immediately after the flowers fade in late spring or early summer. Lilacs bloom on old wood, meaning the flower buds for next year’s blooms are formed on the growth from the previous season. Pruning later in the year will remove these developing buds, resulting in fewer flowers the following spring.

Actionable Step: Mark your calendar! As soon as the blooms are spent, grab your pruning shears or loppers and get to work.
Tool Specification: For smaller branches (less than 1/2 inch in diameter), use bypass pruners. For larger branches (up to 1 1/2 inches in diameter), use loppers. For branches larger than that, a pruning saw or even a small chainsaw may be necessary. I personally prefer a Stihl MS 170 for smaller pruning jobs, as it’s lightweight and easy to maneuver.

2. Remove Dead, Diseased, and Damaged Wood: Prioritize Plant Health

The first step in any pruning project is to remove any dead, diseased, or damaged branches. This improves the overall health and appearance of the plant and prevents the spread of disease.

Step-by-Step:
1. Inspect the entire lilac bush for any signs of dead, diseased, or damaged wood. Look for branches that are brown, brittle, or have signs of fungal growth.
2. Use clean, sharp pruning tools to remove these branches. Make cuts just outside the branch collar (the slightly swollen area where the branch joins the trunk or another branch).
3. Dispose of the diseased wood properly to prevent the spread of disease. Burning is often the best option.
Safety Consideration: Always wear gloves and eye protection when pruning. Be especially careful when using a chainsaw, following all safety precautions.

3. Thin Out Crowded Branches: Improve Air Circulation and Sunlight Penetration

Lilacs tend to become dense and overgrown over time, which can reduce air circulation and sunlight penetration. Thinning out the branches helps to improve these conditions, promoting healthier growth and more abundant blooms.

Technique: Remove about one-third of the oldest, thickest branches each year. Cut these branches back to the ground or to a major side branch. This will encourage new growth from the base of the plant.
Visual Guide: Imagine you’re trying to create more space between the branches. Remove branches that are crossing each other, rubbing against each other, or growing towards the center of the bush.
Case Study: I once worked on a property where the lilacs were so overgrown that they were barely blooming. By thinning out the branches, we significantly improved air circulation and sunlight penetration. The following spring, the lilacs were covered in flowers.

4. Head Back Overgrown Branches: Control Size and Shape

If your lilac has become too large or unruly, you can head back overgrown branches to control its size and shape. This involves cutting back the tips of the branches to a lateral bud or branch.

Method: Make the cut at a 45-degree angle, about 1/4 inch above a healthy bud that is pointing in the direction you want the new growth to grow.
Benefit: Heading back branches encourages the plant to produce more side shoots, resulting in a bushier, more compact shape.
Original Insight: When heading back branches, try to maintain the natural shape of the lilac. Avoid creating a “flat-topped” or “squared-off” look.

5. Rejuvenate Old, Neglected Lilacs: A More Aggressive Approach

If your lilac has been neglected for many years, it may require a more aggressive pruning approach to rejuvenate it. This involves cutting the entire plant back to about 12 to 18 inches above the ground.

When to Rejuvenate: This drastic measure is best reserved for lilacs that are severely overgrown, have very few blooms, or are in poor health.
Process:
1. In late winter or early spring, before new growth begins, use a pruning saw or chainsaw to cut all the branches back to about 12 to 18 inches above the ground.
2. Fertilize the plant with a balanced fertilizer.
3. Water the plant regularly.
4. The following spring, the lilac will produce new shoots. Thin out the shoots, leaving only the strongest and healthiest ones.
Expectations: It may take several years for a rejuvenated lilac to start blooming again. However, this aggressive pruning can often restore the plant to its former glory.
Personal Experience: I’ve rejuvenated several old lilacs using this method, and the results have been impressive. It’s a bit of a gamble, but it’s often worth it to save a beloved plant.

Tools of the Trade: Chainsaws, Axes, and More

While pruning shears and loppers are essential for routine maintenance, larger lilac pruning projects may require more powerful tools. Here’s a rundown of some of the tools I use:

Chainsaws: As mentioned earlier, a small chainsaw like the Stihl MS 170 is perfect for removing larger branches. For felling entire trees or processing large logs, I rely on a more powerful saw like the Stihl MS 271. When using a chainsaw, always wear appropriate safety gear, including a helmet, eye protection, hearing protection, gloves, and chainsaw chaps.
Axes: Axes are useful for splitting firewood, removing bark, and shaping logs. A good splitting axe, like the Fiskars X27, can make quick work of even the toughest logs.
Log Splitters: For processing large quantities of firewood, a hydraulic log splitter is a must-have. I use a 25-ton splitter, which can handle logs up to 24 inches in diameter.
Wood Chipper: If you have a lot of branches to dispose of, a wood chipper can be a valuable tool. It turns the branches into mulch, which can be used to improve soil health.
Debarking Tools: Removing the bark from logs can help them dry faster and prevent insect infestations. There are a variety of debarking tools available, from simple draw knives to more sophisticated power debarkers.
Measuring Tools: A tape measure, level, and marking crayon are essential for accurate cutting and shaping of wood.

Wood Type Selection: Lilac Wood and Its Uses

While lilac wood isn’t typically used for large-scale woodworking projects, it does have some unique properties that make it suitable for certain applications.

Characteristics: Lilac wood is hard, dense, and fine-grained. It has a beautiful, creamy white color with occasional streaks of brown or purple.
Uses: Lilac wood is often used for small, decorative items such as knife handles, jewelry boxes, and carving blanks. It can also be used for making small tools, such as mallets and handles.
Drying: Lilac wood is prone to cracking and warping if it’s not dried properly. It’s best to air-dry the wood slowly in a well-ventilated area.
Green Wood vs. Seasoned Wood: Green wood is freshly cut wood that has a high moisture content. Seasoned wood is wood that has been dried to a lower moisture content. Green wood is easier to work with, but it’s more likely to shrink and warp as it dries. Seasoned wood is more stable and less likely to crack, but it’s harder to work with.

Firewood Preparation: Is Lilac a Good Choice?

Lilac wood can be used for firewood, but it’s not the best choice.

BTU Value: Lilac wood has a relatively low BTU (British Thermal Unit) value, meaning it doesn’t produce as much heat as other types of firewood.
Burning Characteristics: Lilac wood burns hot and fast, with a pleasant aroma. However, it also produces a lot of smoke.
Seasoning: Lilac firewood needs to be seasoned for at least one year before it’s burned. This will reduce the moisture content and improve its burning characteristics.
Stacking Techniques: Proper stacking is essential for seasoning firewood. Stack the wood in a single layer, with plenty of space between the pieces for air circulation. Cover the top of the stack with a tarp to protect it from rain and snow.
Original Case Study: I once tried burning some lilac firewood that hadn’t been properly seasoned. It was a smoky, inefficient fire that didn’t produce much heat. I learned my lesson: always season your firewood before burning it!

Strategic Advantages of Proper Lilac Pruning

Proper lilac pruning isn’t just about aesthetics; it offers several strategic advantages:

Increased Bloom Production: Pruning encourages the plant to produce more flower buds, resulting in more abundant blooms.
Improved Plant Health: Pruning removes dead, diseased, and damaged wood, preventing the spread of disease and promoting healthier growth.
Controlled Size and Shape: Pruning allows you to control the size and shape of your lilac, keeping it from becoming too large or unruly.
Enhanced Air Circulation and Sunlight Penetration: Thinning out crowded branches improves air circulation and sunlight penetration, which promotes healthier growth and more abundant blooms.
Extended Plant Lifespan: Proper pruning can extend the lifespan of your lilac, allowing you to enjoy its beauty for many years to come.

Costs, Material Specs, Timing Estimates, and Skill Levels

Here’s a breakdown of the costs, material specs, timing estimates, and skill levels required for lilac pruning:

Costs: The cost of lilac pruning will vary depending on the size of the plant and the extent of the pruning required. For small pruning jobs, you may only need to invest in a pair of pruning shears or loppers (costing between $20 and $50). For larger projects, you may need to rent a chainsaw or hire a professional arborist.
Material Specs: The only materials you’ll need for lilac pruning are pruning shears, loppers, a pruning saw, and potentially a chainsaw. Make sure your tools are clean and sharp to prevent the spread of disease.
Timing Estimates: A small lilac pruning job may only take an hour or two. Larger projects can take several hours or even a full day.
Skill Levels: Basic lilac pruning is a relatively simple task that can be performed by anyone with a little bit of knowledge and the right tools. More complex pruning tasks, such as rejuvenating an old lilac, may require more experience and skill.

Next Steps: Putting Your Knowledge Into Action

Now that you’ve learned about lilac size and pruning, it’s time to put your knowledge into action.

Assess Your Lilac: Take a close look at your lilac bush and determine what type of pruning is needed. Is it overgrown? Are there any dead, diseased, or damaged branches?
Gather Your Tools: Gather the necessary tools, including pruning shears, loppers, a pruning saw, and potentially a chainsaw. Make sure your tools are clean and sharp.
Prune Your Lilac: Follow the pruning tips outlined in this guide to prune your lilac bush.
Dispose of the Debris: Dispose of the pruned branches properly. Burning is often the best option for diseased wood.
Enjoy Your Beautiful Lilac: With proper pruning, your lilac bush will thrive and produce abundant blooms for many years to come.

By understanding the growth habits of your lilac and mastering these pruning techniques, you can keep your lilac healthy, beautiful, and the perfect size for your space. Remember, a little bit of pruning goes a long way in maintaining the health and beauty of your lilac bush. Now, grab your tools and get pruning!

How Big Does a Lilac Tree Get? (5 Growth Tips for Pruning)