I measured my first Golden Celebration bloom for the season (1st year bush) and it measured at 5" or 13cm. This was the first one to bloom in a cluster of 3, didn't expect it to be so big especially in a cluster.

In my USDA zone 10a Sunset zone 20 garden Golden Celebration, as a freestanding shrub, is about 20' wide by 12' tall growing in partial shade. Reliably fragrant, heavy first and last flushes but reasonably floriferous throughout the year. I'd recommend it to anyone on the west coast looking for a large deep-butter yellow rose for the garden, p'raps not as a cutter though.

Most leaves from the first flush of the year are senile by June and for the plant to look good need to be plucked.

Flowers are produced from late February till early January, last flush of growth comes in around the winter solstice and blooms in early January just as our summer type weather abruptly ends.

If left in an unattended area of the garden with lower branches unpruned this rose will tip-root and produce very vigorous shoots, to 4' first spring, so you may find it suddenly crowding something it was twenty feet from last year. If you want more shrubs keep an eye out so you can move these while still small (the heat makes it advisable not to transplant here tween July and November unless you pluck off all leaves and keep a hawk-eye on hydration.

Large specimens hold up to sun better than many Austins, but no Austin in my climate has a leaf that can hold up more than five months. If anyone can gainsay that, let us know!