Snip the clusters of seed capsules off, being sure to cut only those and not any of the growth immediately beneath them.

its very hard.. without a pic ...

no 'haircuts' on lilacs ... google REJUVENATION PRUNING OF LILAC ... if you want to PROPERLY prune it ...

lilac is not really a small plant.. for a small space ... they do need to be beaten back with a stick.. if they are improperly sited ...

many will be setting buds.. this fall .. for spring flower ... so now is probably not the right time for cutting on them.. generally speaking.. such is done.. just after flowering ...

many shrubs have arching canes ... its the way they grow .. not necessarily something that needs to be fixed .... but again.. a pic is worth 1000 words ...

how sure are you on that ID???

ken

I will take a couple of pictures and put them up for you to see, thank you so much.

The previous owner said they had it pruned back every year, but I'm not sure what that entailed.

yikes on the siting next to the fence .. lol ...

are we sure its a lilac ??? ... something looks wonky to me ... but i havent looked at mine since bloom in may ...

pruning starts with a GOAL ... and i dont understand your comment.. that this plant is weighed down with seed ... frankly.. its a beautiful specimen ... that has spent probably.. nearly.. 10 years growing into that form ... and PERHAPS its only problem.. is that you think its weighed down .....

but if i change that comment to its a bit out of symmetry .... based on the first pic and the branch on the far left ... PERHAPS that whole branch ought to come off as far down as possible.. and then some balancing on the right .. to get back to the vase shape it is ...

lilac if usually pruned thru the rejuvenation process noted above ... but if you go that route.. due to its poor siting ... you might end up with a 12 foot round mound of lilac .. taking over a big swath of the lawn ... and that sidewalk ... and then where will you be ... well.. beating it back with that stick i mentioned above.. lol ...

lets see what others say to that ...

btw ... the small branch and leaves near the bottom ... are the leaves of that plant consistent with the rest of the plant??? .. is it a new lilac sucker ... or some rogue bird dropped other plant.. that need be gotten out of there ...

whatever we plan on doing.. think in shrub time.. which is YEARS .. not one season ... we can always take off more .. next year.. we cant staple bad cuts back on .... which means.. even if that left part fails and breaks .. thats just the plant.. setting our goal of just cleaning up the break with future pruning ... it isnt going to die.. if it breaks ...

hope that gives a newb much to think about ....

ken