Figuring out how much soil you need for your urban planter boxes is a simple calculation that ensures you buy the right amount. First, you need to know the dimensions of each box. A standard "4-foot long" planter box is often 4 feet in length, 2 feet in width, and 1 foot in depth. The volume for one box is calculated as Length x Width x Depth.
For one box: 4 ft (L) x 2 ft (W) x 1 ft (D) = 8 cubic feet.
Since you have three identical boxes: 8 cubic feet x 3 = 24 cubic feet total.
Therefore, you will need 24 cubic feet of soil to fill all three planter boxes. When purchasing soil, bags are typically sold in quarts, liters, or cubic feet. Look for bags stating their volume in cubic feet. You might need to combine bag sizes to hit exactly 24 cubic feet. It's often wise to buy a little extra (about 5-10%) to account for settling after the first watering. Now you're ready to fill your planters and start your urban garden with confidence, having purchased the perfect amount of soil.