Okay. So they sit on top the ground and the rebar holds them in place.The only place that carries those is Home depot...3.85 each. 22 pounds. Center has a hole to drive in rebar. VERY practical & long lasting. worthwhile addition. (Not happy about waiting in line just to get in the store though!!)
What are you planning on planting? With the addition of the 4" drain pipe, it doesn't look like it will be deep enough for root vegetables.