Absolutely! Calculating the soil needed for your planter boxes is a simple process that ensures you buy the right amount. Here's your easy guide.
First, measure your planter box in feet: Length x Width x Height. For example, a box that is 4 feet long, 2 feet wide, and 1.5 feet high has a volume of 4 x 2 x 1.5 = 12 cubic feet.
This number is the total volume. However, you should not fill the box completely to the brim with soil. Leave about 1-2 inches from the top for watering. To account for this, you can reduce the height measurement slightly in your calculation.
Most bagged potting mix or garden soil is sold in cubic feet. If your calculation results in 12 cubic feet, you will need twelve 1-cubic-foot bags. If you buy soil in bulk by the cubic yard, remember that 1 cubic yard = 27 cubic feet. For our 12-cubic-foot example, you'd need about 12/27 ≈ 0.44 cubic yards.
Pro Tip: For deep boxes (over 18 inches), consider using a filler material like crushed cans, plastic bottles, or wood chips in the bottom third to improve drainage and reduce the amount of soil needed. Top with a high-quality potting mix for your plants' root zone.
Happy gardening, and enjoy your new urban green space