A 3’ x 3’ growing area is perfect for growing healthy plants. This size growing area is easy to work with and is a great size for light displacement. With the fill and drain in the middle of the tray, you will not have standing water after the tray has drained. These trays are 4” deep and come in two thicknesses. The Heavy Duty tray is .156” thick and the Econo Tray is .125” thick. Made of black ABS, the ribbed 3 x 3 trays are stress-engineered for complete drainage and maximum strength. Both are super-strong and can hold as many plants as you can fit.