I have a couple of (Midnight Blue x Cinco de Mayo) x Canadian Shield seedlings. MBCDMCS2 has been blooming in flushes while MBCDMCS1 bloomed this spring with one flush and nothing since. Normally I would cull the seedling but I like the color, form has potential as an OGR style, it has moderate fragrance, is nearly thornless and is disease free so far. Three canes were produced this first season with the longest being about 4’. I’m assuming it’s going to be a climber/pillar rose but what I’m wondering is what does the juvenile bloom with no repeat tell me? A once blooming climber? Or could it mean something else? There are a lot of good qualities there that makes me think I should not cull it yet.
I guess it could either mean the once-flowering climber as you suggested as well as possibly a repeater which requires a larger mature plant size. Whether it repeats or not, with its other sterling qualities, I’d think it would be worth retaining for further study and use. Perhaps a self might result in a repeating version of itself? If you have the room, I’d hang on to it until it proves to you it isn’t worth the space.
Agreed. Beautiful potential in the bloom. Congrats!
Perhaps crossing siblings, as well as self.
Duane
Kim and Duane,
Excellent points. I think I’ll keep it and see what I can get from it. Thanks for the responses!
Rob,
I had a seedling that was in a pot for two years and never bloomed. I planted it in the ground and it bloomed once the that year. And this year it started blooming in the spring and is still blooming. I think it just had to get some size.
Daniel
Darn it, Daniel, you’ll make us have to keep all of those interesting once-blooming seedlings with anecdotes like that! 
Delayed remontancy is my pet peeve.
Thank you for sharing that Daniel. Based on your experience I’ll give this one some more time. Nice looking seedling BTW.