Anyone know how to prune a (very!) established lilac 'tree'? With pics

[HelpMeNotKillMyBushPlease]

Does anyone know how/if I can prune this lilac? I've googled, and everything I can see says you can cut back 1/3 per year to renovate - but I'm not sure that's the case when you have one like this that has a large single trunk rather than lots of stems?

I really don't want to kill it, it's beautiful. It would admittedly be more beautiful if I could see the blossoms without having to lie on my back on the lawn.

I'm concerned about chopping off 1/3 of the branches low down, as DP managed to break off a branch last year and it didn't sprout new shoots from where / below where the branch was broken. Just added more growth to the height. Does that mean it's beyond hope?

i'd prune some branches back to about 1.5m above the ground but no more. see how it responds.

what do you want from the tree? do you need it to be much smaller, because it looks great at the moment.

I think the shape that it has grown into is stunning. I wouldn't touch it.

I've done the opposite, and cut all the lower branches off a lilac to try to get it to look like yours. It's beautiful!

Unfortunately mine throws up an unreasonable number of suckers from the base, so I have to keep cutting them down or I wouldn't see the 'trunk'

@parietal I want it to be smaller/shorter as it is very very leggy and you genuinely can't see the flowers any more because of how it only blooms on new wood, which also means it's growing fast. It's partially below a large oak tree and it's desperately straining sideways now to get to sunlight.

I agree, it is stunning @Geneticsbunny but I think I need to do something to stop growing more, it'll just keep going up and up.

I do like that it's big, just not that big! It's completely impossible for me to prune it gently/lightly at the moment. I've even climbed about 4/5ft up it with loppers in an attempt to reach better but even with that increase, what I can reach would mean chopping off some substantial limbs and I'm nervous of doing the wrong thing.

It's about 12/15ft tall atm, if not more, it was quite hard to get a photo that shows the scale! This one might show it a bit more clearly.

Forgot to say, if you want to you can trim the top just a bit to make it denser, based on mine you can cut it just about anywhere and it will keep growing bushier from that point.

I agree understand both of the PPs thoughts. Yes, it really is stunning, but I do also understand why you may want to prune it.

Perhaps cut back the weaker looking branches that are nearer the road (circled in red below), leaving a couple of short stumps and see how it reacts to that? See if it puts out lots of new shoots from those stumps next year.

If it does, and you like what it is doing, then perhaps do this gradually and each year cut back another branch to around 1.5m.

Although BBC Gardener's World do advocate a more extreme approach:

"If you need to renovate an overgrown or leggy old tree, prune when the plant is dormant, in winter. Lilacs respond well to hard pruning and you can cut the whole plant back to around 1m above ground. Because they flower on the previous year's wood, you will lose the flowers for a at least one year. Alternatively you could remove some of the stems over a period of two or three years, cutting them back to the ground – this will ensure that you still enjoy some spring flowers."

https://www.gardenersworld.com/how-to/grow-plants/how-to-grow-lilac/

I would cut just one branch a year as high as you're willing to let it go, it should bushy up from there. I'd start with one on the tree side, as they look smaller. Then see how it goes next year and possibly do one from the opposite side, and so on until it's the size you want it.

But don't lose the clear trunk!

Right, I've just been outside and measured myself against it, much to DPs confusion. The orange line - please note, this is NOT where I'm suggesting I cut it! It's just how tall I am for scale - is 5ft6.

I'd seen that gardeners world instruction too - that's the 1m thing that made me think they were talking about the typical multi stem shrubby sort of lilac and made me scared of following the advice.

I'm so worried if I cut off a branch or 2 it'll just chuck on loads of new growth on the tops of the ones I leave, and I'll just make everything worse. The red arrow is the one DP caught on his van, it didn't sprout at all from there, just did nothing.

I've just Google mapped it, this was it in 2011 (when the people who lived here were proper gardeners who knew what they were doing!) you can see how much more lush and bushy it is. I think I'd like it to be somewhere between then and now in height, but with the 2011 style bushy/denseness to it iyswim.

Lilacs are fine with quite a dramatic prune. It looks like it could do with a good mulch and a regular feed first this summer to see if that perks it up. If it doesn't then it might just be nearing the natural end of its life and that is why it looks less vigerous?
it won't really get much bigger than it is I don't think.

I would take out your DH’s stump completely. There’s a rule of thumb that if you take out a branch just above a branch a third of its diameter or more, then the smaller branch will take over as a main branch. See if you can do anything along those lines

Thanks, that's a good tip about the 1/3 size branches. I'll get out and have a proper look at it today I think with all your collective knowledge and try to make a plan. It's just stopping flowering now so I need to either get on with it or leave it for another year.

We cut ours (similar size to yours) to not much more than a stump. 3 years later it's back to the size it was before, they are hardy!

I don't think I'm that brave!

Did it have a single trunk like mine or multiple stems? Encouraging that it was happy to be hacked back so much though, thank you!

Could I also add it would look beautiful if you leave the grass longer in a perfect circle around the base of the truck.

Hard cut back and it will recover.

%3D

OP I'm in a very similar position with our lilac tree. So much of the advice online is for shrubby bushes so it makes it confusing! Ours is barely flowering in the middle at all now and badly needs a hard renovation prune but I'm scared to do it!

This thread has inspired me to bite the bullet though. It's so gorgeous when it does flower that it's a shame to not give it a chance to look its best.

Pic attached!

You could try following the RHS advice for pruning apples, in other words, accepting its tree shape, but thinning it out a bit.

I don't think Liliac trees live that long 20-30 years is average. It could be getting old which is why it is getting sparse. Pruning may hasten the end.

Ours are doing well then. We’ve been here over 30 years and they were big when we arrived. We lost one probably to honey fungus but the rest are still flowering well