Kind of a related note: I saw a talk by Fred Spicer (Birmingham Botanical Garden Director) on native hydrangeas and vines. I was interested to hear him say that BBG is basically giving up on introducing any more hydrangeas (mopheads, lacecaps, etc.) and only more drought tolerant types (native oakleafs) will be added. He said the watering requirements were too demanding, and he thought it was better to let Aldridge gardens feature these plants in better condition, where they have a lake available they use for irrigation.
So the extra TLC they need has been definitely noted, especially in these dry times, when watering costs are a factor.
