I tried to download and install the gardening stencil found here:
http://www.omnigroup.com/products/omnigraffle/extras/
It's not working correctly. I can only see a few of the objects and the rest are there but look blank: I get the sizing squares when I tap in what looks like a blank portion of the document.
I've tried two approaches to getting the stencil onto my iPad: mailing it to myself (named both "gardening.gstencil" and "gardening.graffle") and by downloading it from Dropbox. In whatever permutation, same result: Mostly blank stencil.