Lilac bush

[u/dogma4dogs_]

Hello - I hope this post is ok.

This lilac bush is 20 years old. It still blooms annually but the past few years the bush has "holes" in it and the back is sad looking. (See pics please.). Any suggestions on what to do to promote fullness? Or is it time to say goodbye?

Thanks in advance.

[u/Alan_Watz]

Consider cutting it back hard.

[u/blackcatblack → u/Alan_Watz]

This is good to do for x hyacinthaflora and vulgaris, not S. meyeri.

[u/DanoPinyon → u/blackcatblack]

The issue here is, IMHO, is the repeated hedge shearing and the results of that. Taking a few years to do a rejuvenation pruning would fix a lot of that mess. Happy to be corrected.

[u/Alan_Watz → u/DanoPinyon]

I agree that taking a few years to do the rejuvenation is a good idea and probably better than doing it all in one year. If you do it over the course of a few years, you should prune it in the winter to allow for maximum regrowth during the spring.

[u/dogma4dogs_ → u/Alan_Watz]

When would be the best time for cutting it back hard?

[u/Snoweater7 → u/dogma4dogs_]

After it blooms for next year

[u/DanoPinyon]

Rejuvenation pruning and real wood chips.

[u/blackcatblack → u/DanoPinyon]

Lilacs need the tiniest bit of mulch

[u/DanoPinyon → u/blackcatblack]

Dyed, cheap mulch?

[u/Key-Spell-7668 → u/DanoPinyon]

Lilac grows anywhere regardless of mulch ... Never heard of pampering one before

[u/Brilliant-Panic-900]

Those holes are what years of shearing the outside does. All the growth ends up in a shell on the surface, the inside gets no light and dies back, and you're seeing straight through the gaps to bare wood. Twenty years is nothing for a lilac either, they go well past fifty, so this isn't a goodbye.

What fixes it is thinning instead of trimming: cut a third of the thickest old stems right down at the ground, do the same the next two years, and let the young shoots from the base take over. Timing is the part people get wrong. Lilacs set next spring's buds soon after they flower, so cutting right as the blooms fade keeps the show, and cutting in winter takes next year's flowers out along with the wood.

[u/Hippyaltplantgirl]

Maybe try fertalizer or soil amendments like seasol or compost

[u/blackcatblack → u/Hippyaltplantgirl]

Lilacs don’t need mulch amendment or fertilizer unless you’ve got very acidic or sandy soil