Is there a possibility that a list of plants to be on sale could be posted on site a few weeks before the event for people who cannot attend but could send friends with a shopping list. I know the RBG in Toronto posts a list in advance and we send friends shopping there.
The plant sales are an activity of the Friends of the Garden, so I really can't speak for them. I've asked in the past (to do exactly as you suggest). However, they sell the lists in advance of the sale and use this to generate some revenue, so the response was definite reluctance to making it available.
Ah yes, I'd forgotten about that list and for my purposes that will suffice but for the Friends of the Garden it would be a simple thing to see which would generate more revenue - a list with I think limited circulation, or a perhaps more widely circulated posted list.
