I planted lilacs here in Petaluma about 20 years ago and they bloom reliably every year. No special treatment of any kind. However, at some point I will remove them because they look like hell when they are not in bloom.

Thanks Sara, that's a good point. On the other hand, they're going to block the view of my neighbors yard o' stuff, so green is better than junk :D

Just follow the instructions. Or ask the local quality nursery. Simple. Done.

I have always found that both peonies and lilacs do best where they have a hard freeze each winter there must be other trees that can grow fast and do what you want that would thrive in California. I grew peonies in Vancouver yes they bloomed but a sad rendition of the ones I grew in Calgary. I would suggest checking out other options for what you want , BTW lilacs also like water.

Exposing the root crown will have minimal impact in improving growing conditions or encourage more flowering. That's not how 'chill hours' work :-) It is actually the topgrowth of any woody plant that needs a certain amount of winter cold to flower or fruit productively.

Many areas of northern California should be perfectly appropriate to grow the standard common lilacs as well as peonies. My climate here alongside Puget Sound is very similar to the Bay area - cool summers and mild winters (I seldom see a hard frost) - and both lilacs and peonies thrive here and bloom heavily and profusely. I am not sure what issues Patricia had with peonies but there are specialty peony nurseries located nearby and several that features lilacs as well and both plants perform perfectly well in this mild climate. We are passing out of lilac season now, but peonies in one of my client's garden yesterday were spectacular in their flowering!!

FWIW, just to clarify a couple of details, peonies are planted shallowly not to improve exposure to winter cold but because they will not flower well if at all if planted too deeply. And that is consistent regardless of where on the planet they may be located, a cold winter climate or not!! Also, once established, lilacs do not require a lot of water.......in fact, they are remarkably drought tolerant. We have recurrent summer droughts here with little to no rainfall from July through the end of September and established lilacs never require additional irrigation.

Thanks Patricia, the lilacs won't lack for water, there's a small natural year round spring coming from a nearby hill that intermittently flows near that spot in the yard, so I'm taking advantage of the natural landscape there. It's defintely not a spot for dry plants, like short-lived ceanothus although other parts of the yard are dryer.

We have a peony nursery not far from here where I've obtained some beautiful specimens; over the years I've found the best for this area are early season herbaceous and most Itoh's. Supposedly the trick in this area is to plant them with the crowns high, something I learned from a gardener from Calistoga on the old GardenWeb site and re-emphasized by the peony nursery owner. Apparently it helps get the entire plant colder, and seems to work.

However, the info gardengal48 provided has my interest piqued and now I want to find out more about how chill works.

Since the general thought is peonies don't do well here (and some of us have found out differently) I was wondering if there are similar tricks with lilacs. Typical general nursery staff don't know and only recommend the Descanso's Lavender Lady and Blue Skies- a bit boring and not very floriferous.

My yard, in a small microclimate on the upslope of Mt Diablo, frequently gets in the 30 degree F range in the winter although it rarely drops below 20F. Snow and summer rain are rare. Roses love it here but too cold for jacarandas and fucshias. Although...I recently discovered a cooler shade spot in my yard with nothing planted so going to experiment with a heat loving fuschia. I apprenticed this week with a Master Plumber to learn how to properly install drip irrigation, what a worthwhile use of my time!

My lilacs don't want for water, I suspect that they look like hell because the summer air is bone dry. They are not particularly lovely shrubs to begin with (when not in bloom) but crispy leaves really make them look awful.