I've had silk flowers in mine for several years. I put a piece of styrofoam in the bottom, stick in the flowers, add the fake moss, and even in some heavy duty windstorms (over 40 mph) nothing has blown away. I do have a couple of small spider plants in the tipsy pot in my backyard, and I put the bark mulch in there and just water with the hose on low. No problem with the dirt washing out unless I have the water coming out too hard.

Hope you can solve your tipsy pot problem and get to enjoy them.
hugs, Karen