Full Member
Posts: 27
Joined: Mon Apr 07, 2008 1:23 pm
Location: Western New York

Too Overgrown or Too Old to Flower?

Hi Everyone,

I'm very new here. Last December we moved into a 19th century farmhouse with some very mature plantings. The elderly couple who had lived here for nearly 60 years hadn't done any pruning, trimming, maintenance, etc. for at least 15 years, so we have some tremedously overgrown plants.

In the middle of our yard, there is a stand of lilac trees about 20-25 feet high and 20 feet around, and a few feet away, another slighly smaller stand that is now blocking the entrance to a small shed. They appear to be very old, and to have not been touched at all in years. Last week, I cleared as much debris as possible from within the stands (leaves, sticks, even 5' tall trees that appeared to have sprouted from seed) and pulled out some dead wood. The green leaves have just started to poke out from their buds (we're in Zone 5b), but it appears that they will not flower.

My question is whether it would be possible for these to ever flower again, and whether it would be wise to try to prune them down to the ground. I loved having lilacs when I was growing up, but I'm at a loss as to what to do with these monsters!

Thanks for any input.

Green Thumb
Posts: 399
Joined: Thu Apr 03, 2008 10:48 am
Location: VA

I googled and found this information, hopefully it will help

How to Prune Lilacs

For the absolutely perfectly shaped lilac bush, you need to prune them each year. Pruning lilacs is a very important part of growing and caring for Lilacs. While some varieties only grow 4 to 8 feet, others can reach up to 30 feet tall. Most will grow in excess of 10 feet. Pruning will not only help with shape and appearance, but also impact plant health and vigor and the profusion of flowers.

There are right and wrong ways to prune a lilac bush. There is also a right and a wrong time. Most importantly, prune or trim back your bush immediately after they are done blooming. Make sure to remove the spent bloom with your clippers. This will keep the plant from growing seeds and encourage creation of next year's buds. Next year's flower bud develops early, even though you may not see it. I have seen inexperienced gardeners trim the tops several inches back. While it looked a whole lot nicer, they loped off the next year's flowers with one pass of the hedge trimmer. By the way, we do not recommend using hedge trimmers. It gives a too trimmed appearance. Lilacs are not hedges.

General Pruning

Lilac bushes should be pruned and maintained each year for a well shaped and healthy plant. The plants should be full looking, yet not overly bushy. If the plant is too bushy, the inner leaves do not get sun and air circulation, an invitation to plant disease.

Trim larger stems from the center of the bush to increase ventilation. It will also afford more room for newer shoots on the outside of the plant to develop.

Pruning should be done immediately after the flowers have died off. Cut small suckers and shoots at or near ground level, or where it comes out of the main trunk. Leave a few strong and healthy new stalks each year, especially if you are planning to trim back old wood.

Trim back any branches that stick out from the main bush, and is not appealing to you.

Topping the bush is not recommended. A flat top is not an appealing lilac shape to most lilac lovers. A slightly rounded top looks best.

It is okay to clip off old, dead flowers at the base.

In trimming and pruning your bushes, remember, beauty is the eyes of the beholder. If you like a tall bush, let it grow tall, If you prefer a wide bush, encourage shoots that have spread out from the main bush.

Trimming Mature Lilac Bushes

If a lilac bush has become overgrown, or is too large or tall for the area you have allotted it, there are a couple of ways to prune Lilacs.

We recommend the three year plan. A lilac shoot takes about three years before it produces a flower. So plan to eliminate 1/3 of the shrub each year, selecting the oldest stalks. Cut them down to just above the level of the soil. As you do, allow new shoots to grow to replace the old ones. By the end of three years, the entire shrub will have been replaced, and you will not go without lilacs for that period of time. Then, continue the cycle each year.

If life with your overgrown shrub has just become unbearable, remove all old stock and leave just new shoots. This is pretty drastic. And, you will go a couple of years with out lilac flowers. But Lilacs are hardy. As long as there are a few healthy new shoots, they will grow back.

I'd rather be gardening!

Green Thumb
Posts: 439
Joined: Thu Nov 09, 2006 11:17 am
Location: Midcoast Maine, Zone 5b

In addition to pruning program it might be a good idea to fertilize these shrubs. After decades they may have exhausted many of the nutrients within their root zone. I recommend organic fertilizers as they are much better for the soil biology. I don't know the soils in your area but here in Northern New England soils tend to be deficient in calcium (Central and Western U.S. soils are often high in calcium). If you don't want to alter the pH gypsum or colloidal soft rock phosphate are good calcium sources. For trace minerals Azomite or Planters II are good options.

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