You're apparently asking about purple leaved forms. Modern selections should be expected to be affected by serious heat but them turning entirely green, with no purple tinting at all seems unlikely.

In 5b in the northeast, they stay mostly purple with only a slight greening on older foliage.

for best info.. always provide your location .... z6 is about half the US ... and extremely divergent ... big city name usually good enough ... and if you plan on hanging around with us ... welcome .. add your location on your member's page ... so it pops up in each post ...

zone is basically minimum winter cold temp ... and really tells us nothing about your summer conditions of heat.. humidity ... etc ... besides.. no one can say.. oh.. i am near you you.. here is my experience ...

ken

It depends upon the variety. Black Lace and Laced up are the best at holding their color, followed by Black Beauty. Black Tower and Gincho Purple turn a dark grey green in the heat of the summer. That is my observation here Michigan.

Thanks for the info. I live outside of Philadelphia Pa. near Valley Forge Park.

I was reading on Proven Winners site about the color change. It is near the bottom.

https://www.provenwinners.com/plants/sambucus/black-beauty-elderberry-sambucus-nigra

One nursery in the area said they were not going to carry it anymore because lack of interest from people. Don't know if to take this as a problem with the plant in this area.