Can you tell us the name of your lilac? I just Googled "lilac chill hours" and learned that old fashioned lilacs need 2000 chill hours but there are newer hybrids which require less.

From what I saw from Googling, they need 2000 hours below 45 F. But the most common cause of not flowering is unintentionly cutting off next year’s flower buds (which form at the base of this year’s flowers) by cutting back too far when deadheading or by pruning after June and cutting off wood that would have flowered next year.

i dont have time to mull this.. but i seem to think that many lilac have the flower buds in fall.... very tiny.. but you can see them if you look ...

so this morning im a bit confused why chill hours is a thing ..

also ....that is why ....if the buds are there.. and you prune in spring.. you are actually cutting off the already created buds ...and why the general rule usually is.. prune just after flowering ...

go to one or 2 high end nurseries in phoenix.. and find the manager.. and simply ask if you can grow lilacs ... if she says no .. then let us know ... if he says yes.. ask him what he will have for sale in spring ...

this really is something you need to be discussing with the local peeps.. now the WORLDwide web peeps ... but if you do find out.. let us know.. its the kind of stuff that keeps us going.. lol ...

ken

ken - my first thoughts re chill and flowerbuds were the same as yours…! But after looking into it, it seems that the flowerbuds form in the summer but need the winter chill for them to develop/mature properly to bloom the following spring. One site (I can’t remember which…) said stressful summer conditions (e.g. unusual heat and drought) could cause the lilac to go dormant early and then bloom in the fall when temperatures fall and rain begins again.

all i know is there was a poor show this year ... after a rather mildish MI

winter ... relatively speaking ... so i hoping they go nuts next year ... [to be clear.. anyone in z7 or above.. would have died in MI last winter.. im not saying it was pleasant.. lol ...wimps... lol]

ken

It'll be interesting to see if they'll bloom in AZ. I have a Miss Kim, which is more heat tolerant than some. It does well. I have not seen many other lilacs so can't compare but I like it. I don't think most lilacs do well here. I'm in zone 7a, NC.

I am not sure that the USDA hardiness zone should necessarily be considered the determining factor on the ability to grow lilacs successfully. Lilacs grow and flower extremely well in my climate and along most of the western side of the Cascade range here in WA state. In fact, one of the foremost breeders of lilacs in the US, Hulda Klager, lived and bred a wide range of common or French lilacs in a zone 8b climate not far from Vancouver, WA. She passed away in 1960 but her gardens are still open to the public and are now a listed National Historic site.

I have grown a number of common lilac varieties in my zone 8b/9a gardens and they all bloom profusely and it is typical to find a lilac or two or more in most area gardens. Despite the very mild winters we typically experience, we still manage to generate a fair number of chill hours (around 3000) or winter hours below 45F.

Chill hours should be searchable by location. Phoenix has only 300-400 so I doubt common lilacs would be very successful in that location.

That sounds encouraging, Gardengal. Do you have hot summers?

"Do you have hot summers?"

Not compared to most of the country :-) Above 85 is rare for more than a couple of days.