Climate does have a lot to do with the size a rose will attain. Obviously roses in the south grow year round and can get much larger than northern grown roses that die back each winter but that's just a generalization. Every yard has it's own micro-climates too so a rose planted in one spot in your yard may out grow the same rose planted in a different spot. Roses are not an exact science but more of an art.

I often look up heights on the suppliers websites (Chamblees, ARE, RU) that are in my zone or similar (So.Caro, Texas)-- I figure if I look at other southern zone 8's on the 7 borderline that my plant will be similar. If you have a winter dormant period when the rose defoliates or just stands still, your rose may never be as big as the biggest height. OTOH if you read the Kordes website (Germany) and you're in 7 or above, your rose could be TWICE as big as Kordes thinks it is. It can be awful hard to figure out which rose goes in the "front row" sometimes..

It's not JUST climate (tho that's a biggie) but the other really important thing is Hours Of Daylight.
Here in SoCal, we get lots and lots of hours of daylight.

Clair Martin (of the Huntington Botanical Gardens) opined that if the English description of a David Austin Shrub said it was maybe 3.5 ft. or lower -- it was likely fairly accurate.
HOWEVER, he said, if the English description said it was 4 ft. tall (or, worse, TALLER) well, then, KATIE BAR THE DOOR!
The thing is likely to rise to 15 feet in Southern California gardens.

He's right on target there, I think.

Jeri

But Jeri, don't you get far less daylight time in summer than more northern gardeners! It seemed the further south in winter more daylight hours but in summer the opposite as is in the north it can be so fewer daylight hours in winter but more in the summer!!! This is where the northerners get some catchup! :)
Pauline

Also they will grow taller in clay over sandy soil. So it's probably a combination and depends on the rose.

I noticed the huge difference too on HMF. I think it would be better if they said tall, medium of small. It actually is an important fact, so maybe one should take moderate climates for recording these growths, probably too not feasible. Or just go by what the growers report on their own averages,T,M and L. How many times are we disappointed because we are growing a tall in front of a small! Hoping for the right moment to ask DH to dig it up to transplant! :)

Please note, I am not complaining about HMF. I think it is an extraordinary source - I use it constantly and am glad of it. It just would be nice, not their fault to have closer accuracies with heights.
Pauline

Apart from varying growing conditions, quite a few new introductions come into HMF from European nurseries, where the roses have a shorter growing season and are pruned harder. Roses are wholesaled to nurseries who haven't grown them before. So initial size information isn't always based on experience. By all means, if the size on HMF is off, add a comment, so HMF can be fixed. HMF is a rose wiki, and rose growers' corrections make it better.

Mistakes also sneak in, like when the centimeters button is clicked instead of the button for feet. If you see an error, by all means, post a comment so it can be corrected.

Pruning also plays a large part in the size of the rose. Some people prune every single spring and their roses are generally shorter than those who never prune (around here anyway...)

So let's say I have a floribunda that HMF says should be 4 feet which it reaches in 3 years... well if I never ever prune it, in another 3 to 4 years it could well get to 6 or 7 feet tall...

I have a miniature Winsome that is supposed to be under 3 feet... It is currently over 6 feet simply because I never pruned it and decided to train it as a miniature climber...

Height is what you make of it...

I agree with Pauline 100%. It is a myth and it is an error to state that the south (east or west, doesn't matter in this sense) has more day light as a rule. In the growing season, from late spring on, norther you go more daylight hours you get. [I remember what a pleasant surprise it was that relatively late evening we experienced daylight in Seattle and Vancouver in July.] Plants reach for the sun and get taller; not only roses but perennials, too.
I planted a Gruss an Aachen in a half shady position where it was over 4' but by now the tree behind and a Gardenia behind it grew very tall, so 'Grussi' is in total shade. I just noticed that it grew to over 5'closer to 6'. I could enumerate various perennials that should stay 2' tall maximum but over 3' or 4' here in the south.

On the other hand, Cass is right. Warmer climates have longer growing season and that also contributes to plant growth.

HMF is a wonderful tool, it'd be ever greater if people would comment and add information about their zone or even mention where they are growing a particular rose. You don't need to post a rose to comment on ones you're growing, information is power. All my roses have exceeded the max heights given, some of them way exceeded. I've had to move roses multiple times because I didn't have the true info I needed, or even info close to what the rose grows to. This includes info from the nursery here in town, my roses exceed what was stated.

My growing season varies depending on the rose, some have active growing for up to 9 months a year. I recorded in Oct and thought I was done, it had been such a late hot summer that they all put out up to another foot of growth in Nov. I take that info and note it in HMF hoping it will help someone out in either my growing conditions or zone, if they happen on those roses I grow. Maybe someday that will save someone else a lot of work also or just give them info they need to make decisions.

BTW Seil, I prune and I have a floribunda that is supposed to be 3-4', it's already 5' tall right now. I have a rugosa that was supposed to be up to 6' tall, it was 12' last Sept. It ended up being pruned too to move it down to 3-1/2 feet tall and a lot of the canes had to be removed when it was transplanted. It's in a sunnier area now than last year, so I'm interested how much taller it'll get:) It's already back to 6'tall now. You could say it's my growing season, but these heights were given by Mr. Moore and the roses are grown right here.

Still I have lavenders That I grew in zone 7 that in 13 years never got to the size they are now in 1-1/2 years here. So, I do think that it is location.

Thanks everyone. I guess if I have one that stays shorter than the one in front of it after several years I will just move it if it is blocked completely. Thanks for all the info. Judy

re daylight hours and latitude,

please check out

http://www.infoplease.com/ipa/A0001769.html

http://www.infoplease.com/ipa/A0001796.html

and compare with the table linked below

Here is a link that might be useful: daylight hours

Interesting Ceterum, thanks!

In view of all the different reasons, one can see how difficult it is to get an even "approximate" height for roses.

We could do a study ourselves, but, we could never work on every rose. I have an idea which "could" work - I will post it later on a separate thread!
Pauline - Vancouver Island (49th parallel, 123 longitude, 6.14 PDT) :smile