In Greta Kustermans wrote:
They don't even agree on the size of Gruss. According to some it is
over a meter (4ft) while others eg http://www.lens-roses.be/html/home-
nl.dhtml?source=presentatie,from=homepage claim that is only 60 cm (
2ft).

Oh yeah. The size estimates are the worst joke in the rose industry. I
wish they'd just say short, average and tall. Even t-shirt size labels
would be better. Eg

Monsieur Tillier: XXL
Kentucky Derby: XL
Granada: L
Double Delight: M
Sexy Rexy: SM

At least then you could take relative climates into account. To
illustrate, I live in Sydney and you live in Belgium. If we both grow
Gruss, mine is likely to be taller than yours owing to warmer
temperatures in winter. But for both of us, Gruss will still be
RELATIVELY smaller than other roses we grow.

On the above scale I would rate Gruss an Aachen an S. It prefers to
flower rather than grow, which makes it an especially good choice for
temperate climates where roses are tempted to throw out long canes.