Raised bed gardening.
My garden is on ground that is pure beach sand, so I do everything in raised beds. I use 2x8 rough sawn cedar and stack them 2 high for a total of 16". The soil warms up quicker in the spring and the 4 foot dimension is easy enough for most people to reach so that you never have to walk on it. Add a few hoops of plastic conduit and you can have a mini greenhouse or shade cloth to keep it cool.
I built one for mom (76), using what I had on hand. Green treated 2x10's and 4x4's, the 2x10's were long enough to use 3 barrel halves and just enough to trim for the ends. I built with enough screw to hold it together till I was happy then took it apart and gave it 4 coats of outdoor stain. Then reassembled with more screws to make it solid. Mom has grown carrot, onions, radish, lettuce, swishchard, beans..... in it. She loves it for the close to the ground crops, and the easy weeding ;-) It measures 26W x 8' 9.5" L x 36 H. The beans are easier to deal with in the large white molasses tubs I got from a local cattle farmer, they are 22" across and 17 H.
Does anyone care to divulge their raised bed soil composition?.
I used 3/4 screened topsoil and 1/4 home made compost and it has worked very well for me. I aim for a foot of this below ground level (I dig out the sand) and at least 12" above ground.
In the beds above I used 50/50 very well composted cow manure/bedding, and the heavy black gumbo topsoil from the woods. Everything grew well. Being somewhat shallow Mom mulches from the top of last falls leaf pile to hold moisture better.