It must be a cut rose rather than a garden rose. Blooms come in singles, their shape is quite pretty, but what I mostly like is the texture of the petals. They seem to be very silky and tender, however they withstand heat very well. What I do not like very much is a very high susceptibility to rust and p. mildew. In our climate (zone 7b, Vienna, Austria) it can be a disaster. This rose requires intence care to have it in its best performance.

Plant and Soil, 104(1): 93-98 (1987)
The effect of root temperature on rose plants in relation to air temperature
M. Zeroni, J. Gale

Abstract
Rose plants (Rosa hybrida ‘Sonia’=‘Sweet Promise’) were grown in heated (minimum night temperature 17°C), and unheated greenhouses with or without root heating to 21°C. These trials covered 6 growth cycles extending over two winter seasons. In the heated greenhouse, root heating did not increase yield, flower quality or plant development. In the unheated greenhouse, root-heated plants grew as well as those in the air-heated greenhouse as long as the air temperature did not fall below 6°C. When minimum night temperatures fell below 6°C, growth, yield and quality were reduced, irrespective of root temperature.

Daytime plant water relations were studied in plants growing at 6 different root temperatures in the unheated greenhouse. Leaf resistance to water diffusion was lowest at optimal root temperature. Total leaf water potential was not significantly affected by root temperature.

One type of rose I am addicted to is a 1970's Grandiflora...............but somehow this one and I never clicked. It began as a "florist" rose and was deemed garden worthy and actually it truly, truly is for it does quite "well" in the natural light and soil, is surprisingly hardy, reblooms well, decently disease resistant as measured against its peers. But, for me, never a "stand out" and odd that it got (1) Big Press on/near release and (2) was assigned the GR class which was, then, nearly a marketing death/second class designation. It ISN'T really a GR, either. It is a hybrid tea with too small a bloom, albeit often a perfectly shaped and heavily substanced bloom. I don't think I ever had one cluster on this one! But yes, the bloom, perfect though it may be, is small and perhaps seeing the promise in the form and substance as per exhibition, Meilland/Star decided on GR since it sure doesn't fit FL and HT, with the blooms so small, would take it off the blue ribbon circuit. And it sure DID and may STILL win those ribbons! And it remains rather available, too but for me, personally, not a stand-out. Want a landscape shrub with almost tiny, perfectly formed blooms? Track down Little Darling from 1956. Want a "GR" that fits no class but has a notable color? Try Prominent. Or try Aquarius which shares that "Not a FL but too small for an HT" trait(s) and has a more interesting color (for me). Or Love, now in some resurrection phase and available everywhere it seems and is red/white and now probably getting some appreciation at long last as it was seen as a near-clunker when released in 1980. Sonia is around, 40 years later, for a reason but has never appealed to me................