Treated wood is okay. How tall you decide to make the beds depends on what you plan to grow in them and how little you enjoy bending over. Don't till the ground before adding your soil.

Good luck! I installed raised beds last summer but the rains destroyed everything I planted. Only managed to harvest a few tomatoes and peppers towards the end of the season. :(

BTW....have you been to One Blue Duck? Delicious!

We built raised beds 7 years ago from an old deck. Took out all nails, and lined the beds with heavy plastic to cut down on leaching of any chemicals that might be left in the old deck wood.

They've held up well. They're about 5'x6', 20" high, with drip irrigation into each bed (we LOVE this feature). Wish we'd done 4'x6' to cut down on the amount of overreaching to get to the center. The height is good for sitting, and rabbits have never gotten into anything in them. I don't think they can see in and therefore they don't know anything's in there :)

We also have lower 'raised' beds that are 10" high, and rabbits mow down anything edible in them. Their drainage isn't as good either, and there's not as much room to top up with compost each year (we have to dig out some old soil first). These lower beds are good for tomatoes, peppers, and taller plants like that, but for everything else I'd recommend the higher raised beds.

I think treated lumber is not good for food crops due to the leaching of chemicals into the soil. I think it is OK if you line the bed with a thick plastic sheeting as someone said above. There are inexpensive plastic boards that look like wood, or are part of a kit for a raised bed. I have found reasonably priced ones at Sam's Club, possibly at a regular Walmart, and at Gardener's Supply online. Some of gardener's supply are expensive and there are shipping costs to consider. If you use untreated wood, the thing is it will rot over time, but can still last a few years and you just replace as you need to. You might want to do a search for "lasagna gardening" which is a way to smother the grass before you start a raised bed, and also add organic matter and nutrients to your bed. You can easily kill the grass by laying just some bags of soil or compost or mulch down and very shortly the grass underneath will be dead. The size should not be too wide, becoz then you have to walk on the bed to harvest, so usually 4 ft wide is the most that's recommended. There are different depth recommendations depending on what you want to grow, like tomatoes and carrots vs lettuce and radishes. Deeper is good, but why waste soil esp if you have to buy bags of it, so I think most people do 8 to 12 inches. Have fun!

Good advice, everyone. My most-wanted crop is tomatoes, so now I'm wondering if 10" will be deep enough. I've had such a problem with anthracnose on my tomatoes the past few years, that I'm hoping that raised beds will overcome that. The raised beds will not be in the same area where the previous tomatoes were grown.

Allen, I was not aware that One Blue Duck had replaced the previous restaurant. From where I live in Hoschton, I seldom drive thru the town square itself. But I will check it out soon!

We have built many raised beds, always 3x4,5,6 even 9'. I just found 3x allowed for reaching with ease, if you are tall,have long arms and no back issues, surely 4x is okay. My first ones were redwood 2x12 planks, we got for free after a lumber yard was flooded. All the others were just plain untreated wood and did rot quickly. I would invest in cedar, 2x6s or even 2x8s and stack them to give you 16". Check out Mels mix, it is great for not having to turn or till in a boxed bed. At the very least add equal parts of compost, vermiculite, peat moss to your native soil. I always used some type of trellis down the center, growing cucumbers beans or climbing spinach, using every bit of space for an intensive garden.