Lowes sells the 4 to 6" round PVC pipe with holes already drilled. Purchase an end cap, fill with rock, soil, and plant. I will often put these in the center of a very large pot to stabilize, and add amazing height and color to a container that has trailing plants (no end cap or rock needed if you are placing in a container)
Just flatten a banana peel and bury it under one inch of soil at the base of a rosebush. The peel’s potassium feeds the plant and helps it resist disease. Consider it a nutritional boost for you and your buds.