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As far as a shrubs go, lilacs are a dream come true for the gardener. Once established, these landscaping beauties will throw out heavenly-scented, long-lasting blooms for years and years-and all with very little care and maintenance on our part. Why is it then, after weeks and weeks of anticipation and doing everything right, your lilacs always fail to bloom? Here are the eight most common reasons.
The fact that lilacs prefer being located on a site with full sun is an understatement. To thrive and flower, lilacs need a MINIMUM of 6 hours of sunlight every day. If your lilac bush is not blooming, check to see if your site is too shady.
A lilac will not bloom before its time, and most varieties of lilacs won't bloom until they reach at least 3 to 6 years of age. Years 1-3 are spent growing and developing. Only then, and only when they are good and ready, will they produce their first blooms. When they finally do bloom, the first few years can be less than spectacular. Don't worry, be patient. It's worth the wait.
Hint: Most lilacs purchased in containers have passed their first birthday and started to develop a good root system. They will generally flower sooner than bare-root shrubs.
Imagine stuffing yourself full of food and then trying to perform something that requires you to expend lots of energy (think Thanksgiving). This is how it is for lilacs getting too much nitrogen.
The primary nutrients in fertilizers are nitrogen, phosphorus, and potassium (on the fertilizer package, they are listed in this order, N-P-K). Nitrogen promotes growth above ground. Phosphorus promotes growth below the ground (roots) and is most responsible for flowering. (Potassium helps with overall growth.) Using a fertilizer high in nitrogen will encourage your lilacs to produce an abundance of green leaves, while at the same time, prevent it from flowering.
Fertilizing lilacs is not mandatory, and if your soil is nutrient-rich, your lilacs won't need feeding more than once per year in the early spring (if at all). When you fertilize, use a fertilizer with twice the ratio of phosphorus to nitrogen in order to promote flowering. Remember, grass craves nitrogen, so if you're fertilizing your lawn your lilacs may be getting over fed. 
If you've recently purchased a lilac for transplanting, it may still be adjusting to its new environment. Even if it was blooming when you bought it, you shouldn't expect it to bloom for the next year or two following transplanting. Lilacs need a fairly long period to settle in. You may need to wait as much as 3 years before it fully recovers.
Lilacs don't like their feet constantly wet, but summer droughts can take a toll on the next year's flower buds. Keep your lilac on a regular watering schedule and adjust it for heavy rain or extended periods of drought.
If you wait too long to prune (after midsummer) you're going to be cutting off next year's flower buds. Pruning should be done immediately after flowers die off, because next year's buds form shortly thereafter. If your lilac bush has become overgrown, cut back only the oldest 1/3 of the shrub each year over a period of 3 years.
Lilacs prefer a soil pH from 6 to 7 (a little on the alkaline side). If your soil is too acidic, or missing certain nutrients, your lilacs won't bloom. And testing your soil is the only way to know. Inexpensive test kits are available at more garden centers, or for the most accurate test, contact your county extension agency for labs in your area. If the results indicate your soil is too acidic, the International Lilac Society suggests spreading fireplace ash around the drip line of the bush for bigger and better blooms.
If you've purchased you lilacs from a reputable local nursery, this probably isn't your problem. Still, large discount garden centers sometimes stock zone inappropriate plants and shrubs. Most common lilacs (Syringa vulgaris) need a cold winter to allow it to set buds. If you live in an area of mild winters, a Meyer lilac (Syringa meyeri) may be a better choice for your garden.
If none of these reasons can be applied to your situation, consider giving your bush a light root pruning in early summer. Jam a sharp spade into the ground on two sides of the plant about 12 inches out from the trunk. And maybe next year will be the year!
I have found lilacs tolerate slightly acidic and slightly alkaline soils quite well. And they do well on clay soils, which will tend to be alkaline. And while I agree with most of the statements made by the author, the best flowering lilacs I have observed are beside old, abandoned farm houses, where the shrubby tree is never pruned, or fertilized - just left alone.
Ask a QuestionHere are the questions asked by community members. Read on to see the answers provided by the ThriftyFun community or ask a new question.
My lilac bush is 3 years old and produced 1 lilac bloom. What do I need to do so it will produce more lilacs next spring?
By Janette
Call a nursery, they will answer your question. It's either still getting established or it needs a soil amendment.
For the last two seasons my lilacs have budded out, but then the buds just turn brown and never open into flowers. They had bloomed fine, if sparsely, before.
Hardiness Zone: 4a
By Lisa from WI
Call your county's extension office; the people there are master gardeners; familiar with your soil, and climate etc; and they can readily and easily tell you what to do! These folks are a fantastic resource! especially for us gardeners! good luck!
I planted an old fashioned lilac 3 years ago and it is still only about 1/2 foot tall. It looks very healthy, but does not grow and no blooms. What can I do?
Hardiness Zone: 5a
By Ruthie from Sullivan, IL
Does it have good soil and full sun?
I planted 2 lilac bushes from my cousin's suckers 4 years ago. The plants look healthy, but I haven't had a single bloom yet. Is there anything I can do?
First of all, make sure your lilacs are getting a full day of sun. Don't plant in too much shade. Watch where the sun falls at different times of the day.
Don't fertilize too near lilacs.
Also, try adding bone meal to the soil.
I bought 3 lilac bushes about 3 ft high 3 yrs ago. They bloomed beautifully, but there have been no flowers since, just green leaves. I did cut hoping to fix the problem. What do I do to get flowers again?
By Pat
You do not say what your USDA zone is, and that may matter. Lilacs will not bloom if it does not get cold enough each year in the winter for them, regardless if they were blooming when you purchased them.
The buds on my lilac just begin to develop, then they turn black and cease to develop into blossoms.
Hardiness Zone: 6a
By Toni from north eastern OH
Most of the country has had an extremely long and harsh winter season this year. I had lilacs in Nevada before I came to Florida, and each spring we had another freeze just about the time the lilac buds were forming. Of course, the buds froze too, and turned black. All the leaves on any trees that had budded out also froze and turned black. If even your overnight temps dropped to near freezing, that will happen, and it also affects fruit trees the same way.
Pat T of Florida
I got a lilac 2 years ago. It bloomed one bud last year, but I am getting nothing this year. It is very green and healthy though. Do I need to put acid on it to help it bud?
By Elaine K.
Hi, I bought a Little Miss Kim lilac from home improvement store and it didn't bloom the next couple of years. It began to bloom and has since. I think you will be fine. I heard lilacs are sensitive and just thought that is why mine didn't bloom at first. Hope it will soon, best wishes.
I have a lilac bush in front of my townhouse. It used to be covered in flowers. Five years ago my HOA chopped it to almost nothing while it was in bloom. Since then I am lucky to get one or two flower bunches. The bush is back to the height it was before they chopped it, but without the flowers. Any suggestions?
By Kathy P. from Aurora, CO
If they chopped yours, they probably chopped others as well, and now yours may not have one to exchange pollen with.
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My husband dug up 4 starts from our neighbor's beautiful lilac bush. The neighbor's bush has never failed to bloom and is just full of them every year!
So anyway, one start was a root with stem and blooming flowers, the other 3 were roots. They all died except for one root start. This was five long years ago and the silly thing still has not bloomed. Not even produced buds. I have never pruned it out of fear of hurting it.
It gets about 7 hours of full sun per day. It has grown beautifully and is about 4 feet tall and about 4 feet in diameter with nice green leaves. Can anyone please help me? I am ready to dig the darn thing up and stomp it.
Hardiness Zone: 11
By Jenny from Paoli, IN
It is OK to prune it at the beginning of spring before the buds show or in the fall. One year, I had pruned back a white lilac bush, belonging to my grandparents, as it was getting messy and hardly bloomed. For the first time in ten years, since my grandma passed away, it was blooming big white clusters of blooms. (06/29/2010)
Lilacs are my favorite flower I love the fragrance and love cutting them and putting them in a vase on the table, they make my whole house smell so good. They do take some time in blooming and only bloom early spring. Be patient and it will happen, there is really nothing more you can do other than make sure you water them in the early morning and every other day and if you want you can use some Miracle Grow solution once every 3 or 4 months, it sounds like you have a healthy plant growing there just love it and be patient it will happen. (07/01/2010)
By Maddy
I planted my lilac bush about 4 years ago. It had never bloomed, until this year when there were lots of blooms! So, it just takes a long time. I started two little starts of a white lilac, it's been growing for 3 years now, I figure by next year there will be some blooms on them. (07/01/2010)
By Jackie
3 years ago I planted a lilac bush. For 2 summers I got some growth and leaves, but no flowers. It is still a small bush, but has once again started to grow with lots of leaves on it. Is there anything I can do to encourage some flowers this year?
Any suggestions would be greatly appreciated.
By Lynn from Ontario, Canada
The flower buds are set in the fall, so if you don't see flower buds as it leafs out, it won't be blooming this year either (unless you have one of the very new reblooming types).
It takes several years to get them to blooming size. They also like to be in full sun. Feed it this spring, and hang in there and wait! (04/22/2010)
By Julie
Hardiness Zone: 6a
By nancy carr from PA
Flower buds or leaf buds? Lilacs take several years to get to blooming size. Don't give up. They do flower best in full sun, so if you could move it this spring while it is still fairly small you'll be better off in the long run. You will probably sacrifice a year or two more of bloom while it adjusts to the move, though. (01/29/2010)
By Julie
How do I get my lilac to produce flowers?
I have a lilac bush a friend gave me. I planted it 9 years ago and it has never bloomed. Please help. I don't know what to do.
I have a lilac bush that has never bloomed. I have had it for 10 years, it gets green leaves and that is all. I have cut it back as I was told to do but still don't get any blooms.
