It grows fast enough that I wouldn't worry about buying a larger size unless you wanted to establish a quick privacy screen or particularly needed a specimen sized plant in a very visible area.

The biggest factor on growth rate will be the planting conditions. If properly planted in plenty of sun and in a well draining, reasonably fertile soil and getting adequate water, you can expect 12-24" per year once established.

where are you franco .... gals pnw west growth rate might be about twice what i might get in MI ...

that said.. there is little instant gratification in the garden ... i would expect at least a year or tow. before a tremendous flower show ... due to transplant shock ... even if you buy a larger specimen in full flower this season ...

all my lilacs came from taking a sucker from below a large plant ... i never took not.. but i would guess it took 3 to 5 years to get to blooming size ... and i didnt care .... that was fine for my expectations ...

i would never go larger than a 2 or 3 footer .... and i would also shop a high end nursery.. and skip a COMMON lilac ... and get a named variety that might be a bit more exciting ...

btw.. sensation is really cool.. but has not been very vigorous.. in terms of massive flower production ... actually.. its the only one i paid money for ... and do avoid that first link at the link below ..

i guess it boils down to what you mean when you say common .... some of the korean Ls are more fragrant.. and a smaller plant ... in the long run ...

ken

https://www.google.com/search?q=sensation+lilac&biw=907&bih=739&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj0t9nT_J7SAhUr04MKHTiIDMcQ_AUIBygC

ken

Ken, "common lilac" is the common name give to any cultivar of Syringa vulgaris. And that growth rate is from MOBOT (among other sources) so should be just appropriate to the midwest as it is here.

but did OP know the mobot definition of the words 'common lilac' ...

i was trying to teach them.. not discount you ...

and as i have mentioned often .. your 9 to 10 month growing season is much more than my ground freeze 7 month .. so location does make a difference ...it was a polite way of not chiding OP for not noting location ...

finally.. the range given was 12 to 24 ... and if i get the lower and you the higher ... then that is exactly what i said above.. yours might grow twice of mine ...

keep up Gods work gal .... peace out .. lol

ken

Finally, a question I can pitch in on. Hooray!

Lilacs grow really fast, up to 2ft a year. I have 8 lilacs, and plan on buying even more this spring. I personally like the Sensation Lilac most of all. They seem to grow faster than the Old Fashioned Lilac. At least that's been my experience.

Thank you, all. Ken, to answer your question I am in Plymouth Michigan, outside of Detroit. Great help gang, thank you.

how about a variegated lilac which has blueish flowers? found one up 23 at Bordines in MI. you can find early, mid and late season lilacs (Miss Kim-but I dislike its fragrance).

Mine is slow, but it's like 50 years old.