In this case, the box was 33 tall x 18.5 wide x 18 deep to house starter plants and those that will reach a max height of about 24. Of course, if you wish to build bigger, add to the below. Materials will depend on what size you want the box to be.
Diy chevron planter box
Diy planter box plans looks like a star
Diy raised planter box kit
12 DIY Homemade Grow Boxes to Control the Growing Environment Home
