Let us know how they work. I tend to let pots dry out in the heat and overwintering on top of cabinets do not get watered well. Curious to see how they do.
Did you try the crystal stuff that you can add to potted plants, window boxes, etc? I forget what the actual name of it is, but the crystals absorb water (kind of like jello) and dry out slowly. Made quite a difference when I was using it.
lesa i do use them and they help. These large planters I want to do with small trees for year round. Big problem is root rot in winter, so need fast draining soil that needs lots of water in summer heat. The water crystals would keep soil to wet in winter.