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Getting Lilacs To Bloom! How To Fertilize, Prune & Care For Lilacs

When it comes to getting your lilac bushes to bloom big and strong year after year, success all boils down to how and when you care for these amazingly fragrant and colorful bushes – or more importantly – how and when you fertilize, prune and deadhead your bushes each spring, summer and fall!

There is no mistaking the overwhelming beauty of a lilac bush. When in bloom, their large hanging flowers bring huge color to the landscape. As if that wasn’t enough, the bursting blooms also fill the air with the sweet smell of spring, a signal that summer is about to arrive in full force.

But lilac bushes bring so much more to a yard than just color. Even when not in bloom, their large bluish-green to deep green leaves add big greenery and interest. Interest that continues on through the winter as they drop their leaves to reveal their intricate branches.

lilacs in bloom - fertilizing and pruning lilacs
Most varieties of lilacs come into bloom in late spring to early summer. With a long blooming cycle of two to three weeks, they are a staple of early season color.

With all of that said, there is no mistaking that the biggest reason gardeners add lilacs to their yard is for those amazing blooms! And for many, it can be disappointing when their bushes flower without much fanfare – or perhaps not at all.

The good news is that when lilacs fail to bloom or bloom weakly, the problem can usually be traced to a couple of issues that are quite easy to fix. And that is exactly what today’s article is all about!

Getting Lilacs To Bloom!

Lilac flowering failure is most often related to three specific care points – fertilizing, deadheading and pruning. And if these tasks are not performed properly, they certainly can cause an issue with blooms and blooming cycles.

But it’s not just how those three chores are performed, but when they are. Especially when it comes to fertilizing and pruning. With that in mind, here is a look at each of those three specific tasks, and how and when to perform them to get your lilacs blooming bigger than ever, year after year!

How & When To Fertilize Lilacs – Getting Lilacs To Bloom

Lilacs can benefit greatly from an annual application of fertilizer. But when you put that fertilizer down can make a huge difference in helping it to bloom, or simply helping it to green up and grow larger.

lilac buds
Lilac bushes need to be fertilized in early spring, before the shrub’s foliage and buds begin to appear.

For more blooming power, you need to fertilize lilacs in the early spring. Early enough that they have not yet or are just beginning to green up. Fertilizing at this point allows the bush to absorb the energy it needs to help power the existing buds to bloom.

Unfortunately, fertilizing after the shrub’s foliage is out, or after it has bloomed will only help grow the bush larger. One time you do not want to fertilize your lilacs is in the fall. Fertilizing late in the season can promote late season growth that puts the bush and future blooms in jeopardy of winter damage.

For spring fertilizing, the best choice is to select a balanced all-purpose granular fertilizer. Sprinkling this around the base and drip line of the bush will allow the energy to absorb into the plant all spring long. Product Affiliate Link : Southern Ag 10-10-10 All-Purpose Granular Fertilizer

How To Prune Your Lilacs – Getting Lilacs To Bloom

Even more than fertilizing, one of the biggest reasons that lilacs fail to bloom is improper pruning. Not as in how you prune your lilac bush back, more more importantly, when you do.

If you want your lilac bush to bloom, there is only one time of the season you can prune. And that time? Right after they finish blooming! Lilacs bloom on the previous year’s wood and on older stems. And if you prune in late summer, fall, winter or early spring, you are going to remove those blooms.

So many gardeners are used to pruning back their plants and shrubs in late fall or early spring. But with lilacs (and most hydrangeas too), pruning at these times is like shearing off their flowers. Even light spring pruning will remove blooms.

Instead, wait until your lilac bush finishes its bloom cycle to shape it back. Luckily, as it just so happens, pruning your lilacs at this point also helps to take care of the third important factor in helping your bushes to bloom – deadheading spent blooms!

Deadheading – Getting Lilacs To Bloom

Believe it or not, leaving all of those old and decaying blooms on your lilac each year can actually have a negative effect on the following year’s blooms. As blooms begin to fade and decay, they still continue to consume energy from the bush.

Plants naturally attempt to heal and power any stems, branches or flowers that are a part of them. Including old blooms. Leaving these in place to slowly fall off can also slowly rob the bush of energy. Energy it could be putting into powering the growth for next year’s blooms!

To ensure blooms the following year, only prune lilacs right after they finish blooming. This allows new wood to grow during the summer for next year’s blooms. Even if you are not pruning, still take the time to remove as many blooms as you can to conserve power.

Of course, if you happen to be pruning your bush back, deadheading, or removing the old blooms, is quite easy to do. By simply cutting the bush back after it completes its blooming cycle, you are also in essence, deadheading.

But during the early years of growth, lilac bushes are not often trimmed. And it is during these early years of growth where deadheading your plant as it finishes blooming is even more important. No matter if your plant is young or old, it is always good to remove as many spent blooms as possible.

Some lilacs can get to be fairly tall and wide which can make reaching every single old bloom nearly impossible. But if you can at least remove the majority, it can save major power for next year’s bloom cycle.

Additional Care – Getting Lilacs To Bloom

In addition to proper pruning, fertilizing and deadheading of old blooms, there are a couple of additional factors that can play a role in helping your lilacs to bloom.

Keeping the area underneath your bush free of weeds will help to conserve energy for the plant. Weeds take nutrients from the soil as they grow, and a lot of them. Nutrients that should be going to the roots of your lilac to help power blooms.

The best way to control weeds is with a thick layer of mulch. By keeping a four to six inch layer of mulch under the bush, not only will it helps snuff out weeds, but it will also help hold valuable moisture in the roots of your lilac.

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Finally, speaking of moisture – don’t forget to water your lilac when conditions turn extremely dry. Lilacs should be getting 1/2 to 1 inch of water per week. They can handle light periods of drought, but extended dry periods will affect future blooming and the health of the plant.

Here is to properly caring for your lilacs this year – and to having your bush bloom like crazy for years to come! Happy Gardening – Jim and Mary.

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