There are special wood you can use, treated or untreated, as well as screws that don't rust, however I already had these materials so I just used what I had.
I also used gardening fabric and covered the whole top, nailed to secure, then flipped over so the bottom was completely covered to prevent weeds.
So to recap make a box out of (4) 2x6 secure together at each coroner until box is sturdy. Then cover to top with gardening fabric, secure until completely covered, then flip your box over so that fabric is coving bottom...you are now ready to fill
Step 1: Proper Drainage
Then you need to fill the rest of the way with soil, I got miracle grow veggie blend, it feeds for around 9 months, it's up to you on your soil. Some make their own compost or buy without feed, depends on if you care if it's organic or not, may try the more organic option next year.
Step 2: Sketch Plan Each Plot(example)
Square foot gardens, I think are easy because, it gives a better outlook and how much space you can use and looks way more organized.
Tip* the viney ones ex: squash, zucchini, melons etc should be on the outer edge that way the fruits will produce over the side and have even more room to grow!
*Veggies that grow up ex: beans, cucumbers I put in the back, that way I can train to grow up my lattice
I sketched out a floor plan if you will so knew where I was planting what. It goes way faster if you do this.
Draw a box on paper (your garden) then make small 1" markers ex: if your garden is like mine 8x6 I had a box with (48)1" boxes inside, should look like this picture.
As I drew out may garden I used this graph to show how many plants can go inside a square foot, I hope you find useful as well...
Step 3: Almost There
Take your twine and wrap around each push pin, going parallel then vertical, when your finished it should look like a grid.
Now you have your square foot garden and are ready to plant!
* note the small fence I have added is just a temp fix until next year. I live near woods so this will help with rabbits and other small animals to stay out. It's chicken wire 20$. you can do the same but I did not include steps for that in this instructable nor lattice, which is twine..
**also keep your sketch, don't throw away like I did mine, that way you know what's growing where, luckily I have pictures lol !!
Step 4: Start Planting
Use your graph you drew, it goes way faster and less stressful if you know exactly what your outing and where. Once you have everything planted, water immediately and do so everyday for the next two weeks, this help them root in and make home in your garden, still water everyday but the first two weeks are a MUST! You don't want your plants to die and all this hard work down the toilet !
Thanks for reading, I hope you enjoyed and good luck in your garden!!