i heard not to used teated lumber for vegetable gardens, but yet i found a site that said cca lumber was safe to use.What is the difference? i heard to use redwood or cedar, problem with that it's cost too much. I'm building 2 raised reds 4x24foot long. I have a lot to grow. a cedar bed 2x4x24foot cost $60 which i think i need two double for a good hight cost $120, a treated lumber 2x6x24 foot cost $35, and 3x5x24 foot 2 together cost $28.What should I do? Any cheaper ideas that are safe?