I drill tiny holes in the shells then stuff them with cactus mix. Seems to be working so far. Bev, I'm still experimenting with plants and I did some pruning after I took the last pics. Here's another one. My mom had this abalone shell for about 30 years.
<div id="LCS_8E9E3331_D360_4f87_8803_52DE43566502_communicationDiv"></div>
And here's another urn
<div id="LCS_8E9E3331_D360_4f87_8803_52DE43566502_communicationDiv"></div>