Lilac care and maintenance, Advice needed

I bought a home in Central PA last year, there is a large lilac bush along the retaining wall. It's been there forever. For the most part, it looks fairly heathly but is wild and out of control. Lots of lilac undergrowth, runners, new baby plants popping up in the yard.

I'd like some advice on care and maintenance, pruning? When, How? There are several OLDER larger trunks, should they be removed and allow the undergrowth to come up? Should I clear the majority of the undergrowth out and leave the larger, older trunks?

Any advice would be greatly appreciated.

Thanks

Pic is from last September, it rebloomed, producing these two small flowers!

Can you post some pictures of your lilac? Might help people give you better advice on how much ought to be pruned. As far as when to prune, just after blooming is the best time, if you do it too late in they year then you will cut off next year's flowers.

Okay, I am well qualified to answer this one. I moved into an older (1950's) home with lilacs in a row on a side. They were the old-fashioned kind, two varieties. I THOUGHT that, with my inherited green thumb, I would "rescue" them. First year, I threw all sorts of amendments around them. Bravely, I fought all the new suckers to go into the Lilac jungle, trying to find viable, healthy suckers, but really only found "petrified" old, huge, remnants of trunks. Lots of mildew, even more borer evidence, few blossoms, but oh! Nothing like the scent of an old-fashioned lilac! Cut, hacked, hauled away to my heart's content. Too busy for the first summer to notice the last problem, but NOT the second summer. My painter noticed, too. There was the weirdest huge wasp-like bug, seemingly making the Lilacs miserable and sticky, feeding off them! My painter said he had the same experience, and as his son is allergic to bees, out they went. So, having to concede defeat, I asked him to do the same with mine. I have hired someone to dig out more since the original death stroke, and see that I am far from done, as many suckers are determined to live. I have a well and am very into natural/organic measures, so dig away I must. I hope that this helps you - wait until the bees arrive...oh just wait...! best of luck!

Follow the general rules of pruning: Dead branches go first; then branches that are crossing or rubbing, then prune for shape and to open up the center. Make your cuts at an angle, close to but not at the trunk or main branch. To rejuvenate, cut one third of the old trunks back to the ground (after flowering) and cut no more than a third of the height of the remaining branches. Of course the sucker plants coming up in your yard can go any time.

Google "pruning" for diagrams on how to prune trees and shrubs. One good picture can be worth a lot of words!

I have an old lilac that has been tortured by a know-nothing lawn service company and subjected to my own uneducated pruning efforts, before I wised up. It's still going strong. There isn't much you can do that will permanently damage a well-established lilac besides cutting the whole thing down to the ground...which my next-door neighbor did to his lilac...and yet, it came back !

Altoona, PA is a very different part of the world to Warrenton, VA and to northeastern IL (Chicago 'burbs). Despite the good intentions of these gardeners, their experiences with their plants are not that relevant to what should happen in northeastern PA.

I would really advise rothdavid to take a look around for established plants and/or botanic gardens and arboreta, and see how these plant collections are managed and seek local advice. Lilacs are a species that are planted far and wide, but perform markedly differently as you move from cooler/shorter growing seasons to hotter/longer growing seasons. They like north/cool/short best. The finest lilac collection I have ever seen is in the Royal Botanic Gardens, Hamilton ON. Next best was in Highland Park, Rochester NY. The Arnold Arboretum in Boston is not too shabby. One of the best lilac growing concerns was also located there, run by the estimable Coggeshall family. The late Father John Fiala wrote a worthy tome about lilacs and their propagation - he resided and hybridized in Medina OH.

These are the types of resources someone from Altoona ought to avail themselves of. I would never just whack away at what otherwise is a perfectly healthy plant. Prune out dead wood, and step back and take a season's breather. Observe how the plant behaves over a growing season or two before making any decision about radical alterations.

You can always remove more. You can't put it back.

Thanks everyone for all the advice. I will take some pics this weekend and post. The lilacs appear healthy. They are loading down with blossoms too, which is a bit early in the year..

Zone 6a is one zone away from 5b, isn't it? Not soooo different. But I defer to VV's superior knowledge. And I did not mean to imply that you should hack down your old lilac, David!

I didn't mean any offense to anyone posting here - certainly not. All opinions offered are good, just not always for everywhere else.

Zone 6a and 5b are adjacent temperature zones, but I think you'd have to agree that the prairie-like conditions often found in northeast IL are quite different than the valleys of the Allegheny Mountains where Altoona is located. At least last time I checked...

More so as you head to southerly reaches like Warrenton, VA. I'm not surprised that lilacs are not happy there.

Again, no judgement made on what is right in your garden. I'm only counseling toward how rothdavid might approach management of his plants.