Q&A for How to Prune Lilacs

It is best done right after the tree has finished flowering, and should not be done until the tree reaches about 6-8 feet in height.

It is best to isolate about 1/3 of the flowers that are still unbloomed and have a thick healthy stem. Remove the rest of the flowers by making the cuts at a 45-degree angle about 1 inch from the bottom of the stem.

No, cutting them in the fall will cause you to cut off the next year's blossoms.

You can deadhead them during the early years of the plant's growth after the plant flowers. Removing the dead flowers allows the plant to focus on creating more blossoms.

Yes. Removing dead and dying leaves and branches assures healthier growth in the future.

There are many likely reasons such as not enough water or sunlight, but at my house the problem is pocket gophers eating the roots of the bush. Look for gopher holes near the lilacs, and trap them with a Victor trap or something similar.

Yes, but it is better to trim the old blooms as soon as they turn completely brown (look dead). Also when trimming the old blooms, cut back about a few inches on the branch to rid the area that has lack of nutrients to the bloom.

I've found that leaves often don't survive the transplant, but roots will still take hold and grow the next season. I'm not sure what you mean by "extra help for the roots." If you added strong fertilizer or compost, it could have been too much.

You would have to get most of the main roots with the bush. The roots are similar to tree roots; however tall the tree, the roots are 2-3 times longer.

Yes, it is perfectly fine to trim a lilac bush during summer.

Yes, as long as you cut above the graft.

Mid-winter through early spring, before any buds appear, and also between blooming stages, but that can cause less blooming for the rest of the year and into next year.

They will return next season. To reinvigorate the lilac, give it a good pruning using pruning techniques from a good gardening book.

Yes, and runners will grow underground, causing new lilac bushes to start to grow.

I had the same problem. I watered the bush with a solution of one tablespoon of garden Epsom salt and a gallon of water just prior to bud out in early spring, and boom. The best thing to do is take a soil sample to your nearest university agriculture extension facility to find out if your soil pH and/or nutrients are ideal for lilacs. Also, proper pruning helps the plant use its energy for blooming.

You'll want to use a ladder, a pair of long-handled clippers, and a lot of caution.