Filling your urban planter boxes is an exciting step, but the cost of soil and amendments can vary. For a realistic estimate, you first need to calculate the total volume of your boxes in cubic feet. A typical mix for healthy containers is 60% high-quality potting mix, 30% compost, and 10% perlite for drainage.
Expect to spend between $3 to $10 per cubic foot for bagged potting mix from a garden center. Compost may cost $2 to $8 per cubic foot, and a bag of perlite is around $15-$25. For example, filling a single 4'x2'x1' planter box (8 cubic feet) could cost roughly $40 to $100+ for materials, depending on quality and brands. Buying bulk soil can significantly reduce costs for larger projects.
Remember, investing in good soil from the start saves money on plant replacements and fertilizers later. Start with a clear plan, measure your boxes, and shop around for the best local or bulk prices to fit your urban gardening budget.