I planted a number of elderberry bushes across the front of my property a few years ago. One side of the yard is low and can have standing water for days after heavy rains. Last summer, after especially heavy rains and hot weather, I noticed the elderberry that were in standing water were wilting and dropping their leaves. The ones on higher ground were fine. I found out (probably on this forum) that elderberry can "tolerate" wet feet, but it depends on the temperature of the standing water. The warmer the water, the less oxygen it holds, therefore if the water is especially warm, the plant will suffocate. After the yard dried up, the plants came back.

Thank you Echobelly. Very helpful.

Were they in sun or shade? Any special care that you needed to do.

I actually was just reading about someone growing them. Check out this site; he could probably really give you some great tips.

Here is a link that might be useful: elderberry in Florida

I've been growing for a few years. Was told that they like it damp and that they can be sort of invasive. I planted them in a dryer area thinking that would "cure" the invasive problem. Maybe it has to an extent but it still suckers some. But more to your question about shade...mine gets some but I would not say it is an understory plant for me. But then again although it blooms it holds very few berries. So it that because it is in a dry spot or because it is in a sunnier spot? Mostly I think it is a weed...I love this weed...but it can take what you give it but it might not do its best.
Anyway you have given ME something to think about :-)