Hi
I don't prune my elderberries, but maybe I should. They grow wild on my property. When I see then in early spring I just mow around them and let them grow if it's a convenient spot. As for water, in the heat of summer I will give them a drink if the hose is nearby. My muscovy ducks love a small kiddie pool so I move it around my yard. Most days I rince and refill it while moving it around the yard. That way more areas get water and fertilizer and the ducks can't make a mud hole.