I have a huge lilac weed that I want to get rid of, but I'm not sure how to go about it.

I trimmed it back as far as I could about two years ago and it came back with a vengeance. It was planted about 6 inches from the house and I think it's a royal PITA so I want to get rid of it.

I trimmed it back again using a hedge trimmer and light duty electric chain saw. It's about three feet across and has about 20 "trunks" coming up. I've taken trees down by cutting as close to the ground as possible, but with a lilac, it'll just keep coming up from the roots. Now that I have it trimmed back this much, can I just start hitting anything green with glyphosate whenever I see it?

I'll try hacking more of it away to see if I can get close enough to dig it out, but I'm wondering if anybody has ever gotten rid of a lilac that is over 20 years old and if so, what it took to do it.

Lilacs. When you want them, they refuse to grow. When not, they grow like weeds. I have two fairly coddled ones (one old-fashioned lavender, the other a Miss Kim).

Glyphosate when it regreens should take it out. Eventually.

I haven't found a lilac that you can trim enough to keep it in check. You can cut it down to zero every year, but until you dig it out, its not going away. I haven't tried to kill mine, just manage it. I suppose if you poison something enough, it'll go away.

southerncalpal wrote:I haven't found a lilac that you can trim enough to keep it in check. You can cut it down to zero every year, but until you dig it out, its not going away. I haven't tried to kill mine, just manage it. I suppose if you poison something enough, it'll go away.

I shape the canes, remove any side sprouts, and restrain my front-garden lilac horizontally. That works fine, but does take some work. It's not a bush you can ignore for a year between cuttings.

The Miss Kim is kind of hefty at the moment, but I wanted to see it in full bloom. I'll pull her back shortly.

I just wish I would have realized I'd need to kill it before I whacked so much of it away. There's not a lot of green left to absorb the glyphosate.

Lilac blooms on old growth. It also regenerates every year, and has a pre-dispositioned size. I'd guess most lilacs reach that size in 3yrs without pruning (I dunno though, I'm not a lilac expert in the least). I just know they're a lot like spirea in a northern climate, and imagine they're stronger south of here.

southerncalpal wrote:Lilac blooms on old growth. It also regenerates every year, and has a pre-dispositioned size. I'd guess most lilacs reach that size in 3yrs without pruning (I dunno though, I'm not a lilac expert in the least). I just know they're a lot like spirea in a northern climate, and imagine they're stronger south of here.

Depends on the lilac. Miss Kim above is three years old and at her adult height (she's not a tall lilac, nor especially wide, and is tolerant of shade). I won't reduce the height, but will reduce the width into more of a vase shape, and cane the whole outer ring.

My old-fashioned lilac is also three, about five feet tall, and nowhere near its adult height (which is, theoretically, twenty feet). I'll never let it get that tall.

Way back when in my early childhood home, we had a fully mature lilac of the same species as the one out front. It was fully 20 feet tall and 30 years old, but never bloomed much down below. If I knew then what I know now, I would have caned it back progressively smaller to encourage blossoming down where people can see and smell them.

I just wish I would have realized I'd need to kill it before I whacked so much of it away. There's not a lot of green left to absorb the glyphosate.

Just wait. After cutting, they grow with a vengeance.

MorpheusPA wrote:It was fully 20 feet tall and 30 years old, but never bloomed much down below. If I knew then what I know now, I would have caned it back progressively smaller to encourage blossoming down where people can see and smell them.

We bought our house a little over a year ago and there are two huge lilacs that I would like to get into better shape. They are a bit unruly at the moment... I don't know where to begin with them! I need to research how to properly prune them...

Bentface1 wrote:

MorpheusPA wrote:It was fully 20 feet tall and 30 years old, but never bloomed much down below. If I knew then what I know now, I would have caned it back progressively smaller to encourage blossoming down where people can see and smell them.

We bought our house a little over a year ago and there are two huge lilacs that I would like to get into better shape. They are a bit unruly at the moment... I don't know where to begin with them! I need to research how to properly prune them...

Cane a third of it to the height you want, or a little smaller. Next year, cane the second third. The third year, finish up the last of it. That keeps it from failing to bloom--by the time you do the third caning, the first is more than far enough along to bloom again.

Unruly side branches can be hacked off. Huge, established lilacs aren't particularly touchy about having those removed.

So, I can just trim 1/3 of the larger branches to the desired height? This seems fairly simple... I was afraid to do anything too drastic as I didn't want to harm it. Is that okay to do now or do I need to wait until another time of the year (fall?)?

Bentface1 wrote:So, I can just trim 1/3 of the larger branches to the desired height? This seems fairly simple... I was afraid to do anything too drastic as I didn't want to harm it. Is that okay to do now or do I need to wait until another time of the year (fall?)?

Just post-blooming (or, around now) is best, before the new buds begin to form (usually in June). I took the unattractive side branching and fountain branches off the old-fashioned lilac. The Miss Kim will get done as soon as blooming stops in a week or so. Cutting in fall will remove any new buds (which are there, you just can't see them). Since lilacs bloom near the tips, that's not a great thing to do.

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There's the whole story. Depending on how unruly your bush is, you could just cut it back hard. You'd give up flowering, but if it's really all over the place that might be best. If you limit the cut to about six feet and then cane out the one third, you'll still get a bit of blooming next year (but the bush will take time to fully regenerate and bloom a lot again).

I'm not shy about removing side branches I don't like at any time (I don't care to see blooms on a hideously mis-shapen branch anyway). Dead wood gets removed as soon as I see it. I never bother dead-heading.

Properly trimmed lilacs actually bloom better, and the blooms are down closer to where you can see and enjoy them.

I got a callback from a tree service I contacted over the weekend. They'll dig the stump out and haul it off for $150. I think that's money well spent.

He did warn me that I'll have to watch for lilacs sprouting from remnants of root left behind. I told him I plan to keep the roundup handy for years to come.

I'll just follow Mad Eye Moody's advice: Constant Vigilance!

bpgreen wrote:I'll just follow Mad Eye Moody's advice: Constant Vigilance!

For lilacs, you'll also require a Foe Glass to see them coming and a good death curse, which is regrettably unreliable in this case.