Dude... are you saying your Arachnoideums rot without rain protection? Regardless of arrangement?
I didn't have any Arachs rot last winter... but I only had a handful. I have more this year, and more congestion.
Hmmm... I think I need two things:
1) Knowledge of each cultivar's growing habit
2) Patience
I have neither.
Consider the following two cases:
This one I planted hoping it would drape down on gossamer threads and adorn those rock faces. Epic fail 1.
This one I hoped would bunch up in that rock crevice. Instead
this one made long thread-like stolons that I had to push back and stack on top of each other. Epic fail 2.
I think I'll take the second one and put him where he can drape down a creviced rock face.