'Golden Wings' is a better rose for tough scenarios, even in the PNW. Capt. Thomas is a bit of a relic. If anyone is looking for a modern yellow single, large shrub, then 'Flutterbye' and 'The Magician' are decent choices, unless you live in more arctic areas.
CT or CW? CT is horrible here, in most aspects. GW is great here, but some lower leaf BS. Nothing to care about though. It essentially takes care of itself. My old one is like 8'T x 7'W lol. 3 flushes per year, even in the heat of August. Zero watering and fertilizer.
Ah, yeah. Early Pernet hybrids typically do poorly here, right after spring season is finished. Exceptions are roses like Lafter, and so on. Rosa foetida itself just melts here. Literally, the foliage melts from disease, right off of the plant.
While the color of Captain Thomas's blooms is officially "white," blooms can range from a very intense yellow, as seen in my photo, to virtually white. In our very hot climate, blooms tend to be far more white in the hotter months, though I've seen blooms open yellow even in the heat and then fade to white or off-white. In my opinion, its color class should really be light yellow.
You are right, Captain Thomas does bleach in the hot sunshine but in the PNW he stays a constant yellow. It must be very hard to define a rose colour when it can change in the different zones.
Right you are, Lynette. But it seems to me that with Captain Thomas, the scale would tip toward at least "light yellow" rather than white, even here in the low desert.
