Squirrels here leave them alone. The bulbs just fade out by themselves, no help from squirrels required. If you want truely stunning tulip displays I guess you have to dig em up after bloom and replant or just keep adding new. I was told to plant deep and that really does help. Also besides the darwin tulips try tulips from the early group. My early single mix from Scheepers is on the second spring and has had very good return this year. I did take peoples advice and planted all those tulips deep. 10 inches deep to help them keep coming up. But still, I am definately going to be adding lots and lots more tulips this fall.
