I can't see a photo, but when did you plant them, and where are you? It's been a pretty dry summer for most people in NZ... Young trees can need regular watering through at least their first summer. Are the trees mulched? Thick mulch, NOT touching the trunk, really helps reduce evaporation and competition. I'd give them a really long, deep water at the roots(like leave the hose on low under the mulch for a couple of hours). Plums especially, like quite a bit of water.

Will americana pollinate the Bruce plum, too, do y'all think? I have both of those but the Bruce hasn't flowered yet. I know it needs a pollinator, and I'm hoping my wild plums will do the trick (I read he's half Chickasaw plum?). I have wood of that americana, too, if anyone needs that :) Any time. It's a wide tree by my woods across the road. (The fruit is pretty big for a wild plum, but I won't know if it makes tasty preserves until later in the year.)

Paul, the best thing for you to do is to grow Black Plum and your Purple PLum at the sane time in the same season and see if you see any differences. I've grown Black Plum and it is a very dark color, and even more so when grown in southern areas. Purple means pink to many folks and purple was the word used to describe pink fruits years ago starting in the late 1800's, as in Prudens Purple, which is Pink, Eva Purple Ball, which is pink, and many more. So do try comparing the two under the same conditions. Carolyn

I have a santa rosa plum in a container NYC 7B, year 3, it came out of dormancy a bit early this year and had a few blooms and shoots and we had a severe high wind and cold temp events. I got what you got but worse