(I love this plant. Could grow it in OK, but not sure about Colorado?) This attractive form of horsetail (Equisetum) is an invasive spreader, but confined to a planter like this, it's well-behaved AND a cool architectural addition.
12 houseplants that can survive even the darkest corner
Inspire Your Guests with Creative Pallet Creations
Here is another idea of creating the planter for the garden in the home, but this one is big. You can see how reshaping the wood pallets can turn them into awesome items for decoration. There is no need to paint them as they look amazing in their actual color.