Soil calculator for Mississippi

An ordinary 4 x 8 raised bed at 12 inches deep takes 32 cubic feet of soil. That equals 1.2 cubic yards, often more than a first bed builder expects after planning on a few bags. Use this calculator to size any planter, bed, or yard job for the three available soil types. Blend affects weight: garden soil runs about 2,000 lb per cubic yard, screened topsoil is 2,200, and fill dirt is 2,400. Select the soil you intend to order so the tonnage is calculated correctly.

Three-step bed calculation

1. Record the length and width of every planter or bed in feet. Use multiple-areas mode to combine the totals.
2. For existing beds, use 4-6 inches; new in-ground beds call for 6 inches; an empty raised planter needs 12 inches.
3. Divide cubic feet by 27 for cubic yards. Multiply yards by 1.0 to 1.2 for tons, according to soil type.

Coverage and weights

Choose soil for the job

• For vegetable plots, flower beds, and planters, choose garden soil blended with compost for planting.
• Choose screened topsoil for lawn areas and final grade work. The Topsoil Calculator includes example depths for lawns.
• Use fill dirt below to change grade or fill holes, reserving good soil for the planting layer above.
• Instead of replacing a worn-out bed, work 2-3 inches of garden soil into its upper 6 inches. That uses less material and gives roots a better transition.

Fill raised beds without buying too much blend

Do not run costly blend through the full depth of a tall bed. For beds above 18 inches, use a lower third of fill dirt or coarse organic matter that decomposes in place, then put 8-12 inches of garden soil where the roots will feed. Calculate each layer separately with two quick runs. In Mississippi clay, measure the full 12 inches rather than guessing at the depth.

Example: three 4 x 8 beds

Ninety-six square feet at 12 inches deep comes to 96 cubic feet, or 3.6 cubic yards and about 3.6 tons of garden soil. Order 4 yards. The compost in blended soil consolidates, causing roughly 10% settling in the first weeks, and the extra material can refill the beds afterward.

Improve clay and sand in place

Dense clay sheds water slowly, while sandy ground loses moisture quickly and leaves plants short between watering. Treat both by mixing 2-3 inches of compost-blended garden soil through the top 6 inches, then repeating over a couple of seasons. That is a third of the material and labor needed for total replacement. In Mississippi clay, building the growing layer this way helps water move through the bed. Use full-depth replacement only where debris from construction or contamination makes the existing ground unusable.

Bulk soil or bagged soil

At 40 lb each, a cubic yard is about 36 bags. A single raised bed can require 43 bags, which means loading 43 bags twice. Bulk costs less by the cubic foot and arrives in one tip, while free delivery means there is no truck fee to recover. Bags are best kept for topping off one planter. Have the pile tipped onto a tarp: soil can stain concrete, and cleanup is just dragging and folding the tarp.

Soil amounts for beds and bags

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