I was eating Pistachios today, and tried to figure out what to do with the shells. While they can recycled into compost, even with a vermiculture system they can take a while to break down.After observing the fact that my Desert Rose was not properly draining, as I had put a paper towel in the bottom of the pot when I repotted it last, I decided to use the shells to aid to drainage. I unpotted the Rose, removed what was left of the paper towel, then filled the bottom of the pot with a layer of shells, and repotted the plant. The pot drains wonderfully now! I highly recommend recycling your pistachio shells in this manner!