In z6b Connecticut tall ones like Mister Lincoln would get to six or seven feet but this was after getting well established in great soil. Weak shorties like St Patrick that regularly got killed to the ground in the winter might get only to two feet. In California people don't cut them back and the winter wont do it so they can become huge woody monstrosities. They wont do this in New Jersey but they will get big enough and again the answer will be grow them in good organic soil.

You may be able to get a pretty good idea of how big some of your roses would get by visisting the two roses gardens in the city. Both have a good number of Austins. I know the one in Bronx should have a list of their roses on its website.

I cannot say anything from personal experience: all my ownroots are either 3 or 2 years old, and it is too early to tell. I doubt they will get anywhere nearly as big as those in Cali: we have a far shorter growing season and blackspot pressure might also slow things down quite a bit.

Hi Drew

So much depends on the genetics of the rose and the growing conditions that it is really difficult to predict eventual outcomes. Even within the Austin stable, there are huge variations in growth size. What I would suggest is to pay some careful attention to locally grown roses (and probably be more querying than a mere physical evaluation because water, soil types, nutrient factors all have a bearing on the eventual size and shape of a mature rose....which will, incidentally, take a few more years before yours have reached their full potential. Austins typically take around 4 years to really get going....and even then, the girth of the canes will alter, changing the overall shape, from a loose framework at the beginning, to a much sturdier rose after a few years. If you find you are unhappy with the placing, it is a simple task to move them around during their winter rest phase....so just enjoy the growing period and maybe fill in extra space with some direct sown annuals until your roses are nicely filled out. But do be aware, the smaller Austins (Mary Magdalene, Anne Boleyn) hover around 2.5 feet while monsters such as Graham Thomas, Constance Spry, The Generous Gardener etc. can all top 3metres, even in a cool zone 6.