How To Figure Out How Much Soil I Need.
Follow these steps to determine the right amount of soil for your project.
- Break your project down into square or rectangular shapes. If you have an L-shaped garden, you’ll find it’s easier to use a soil bed calculator when you turn it into two rectangles or a rectangle and a square, depending on the shape.
- Measure the length and width of your garden beds using a tape measure.
- Determine the depth for your garden. You’ll find more information on properly estimating the depth for your project in the sections below.
With this information in hand, you can use an online soil calculator to handle the rest of the math for you. However, you can also do this math yourself fairly easily.
- Multiply the three measurements (length x width x depth) to get the soil volume needed for your project.
- If you divided your space into multiple sections, add the volume for each section.
If you used feet for the above measurements, the resulting number will tell you how much soil you need in cubic feet. If you have a very large number, you may want to convert it to cubic yards and purchase your soil in bulk. You can convert cubic feet to cubic yards by dividing your total by 27.
How To Calculate Soil Needed for Raised Beds
Raised beds come with some special considerations when you’re calculating your soil needs. Before placing your beds, you should till the soil to a depth of 6 toÂ 10 inches. This will improve drainage for the bed on top and allow your plants to send their roots deeper than the bed itself.
Tilling the soil will loosen it initially and may create more space for it to eventually settle. When you’re calculating your soil needs, you should always round up. After filling your raised beds, you’ll likely find that the soil settles down and leaves you with an inch or so of extra space at the top. If you’ve prepared extra soil ahead of time, you’ll have the perfect medium on hand to top off your beds as this happens.
How To Calculate Soil Volume for a Garden
If you’re creating a garden on existing soil, you should blend the soil that’s already there with a new layer of topsoil. First, you need to till the soil to a depth of at least 6 inches. If you have a rototiller and can till the soil to a depth of 8 to 12 inches; this is ideal.
Tilling the soil will help aerate your garden so your plants’ roots can penetrate more easily, sinking deep into the earth. Once you’ve tilled the garden, you should add 2 to 3 inches of topsoil. Working with your soil volume calculator or the equations listed above, you should enter a depth of 2 or 3 inches and calculate the length and width of your garden in inches, as well. Divide the final number by 12 to convert it to cubic feet.
Your topsoil shouldn’t remain on top of the garden. Till your new soil into the existing soil so your plants have a rich blend of nutrients that’s at least 6 inches deep.
How To Calculate Topsoil for Your Lawn
If you’re top dressing your lawn to improve your grass, you need just 1/4 inch to 1/2 inch of soil coverage on top. This may seem like a very small amount, but you may find that it adds up quickly if you have a large lawn to cover. When you’re performing your soil calculations, make sure you’re using inches for the length and width of the area and calculate the depth as 0.25 for 1/4 inch or 0.5 for 1/2 inch.
Alternately, you can skip the more precise calculations and estimate about four cubic feet of soil for every 100 square feet of lawn.
How To Select Your Soil
Different projects require different types of soil. For a raised garden, a good balance is generally:
- 60% topsoil.
- 30% compost.
- 10% soilless growing mixture, such as peat, vermiculite, or coco coir.
If you’re adding topsoil to your existing soil, you need to evaluate what’s already in the garden to decide what the best additions are. Soils are typically a blend of clay, sand, and silt. If your garden is heavy in one of these mineral particles, it’s often best to balance it out with those that it’s missing. Loam is a balance of all three.
You must also take your plants into consideration. Some prefer sandier soil while others can thrive in clay. All soils are improved by organic matter such as composted yard waste or manure.
Compost will help you maintain a good pH level in your garden, as well. Most plants prefer a pH level between 6 and 7, which you can test with a home kit or by sending a soil sample to a lab. If your pH is outside the preferred range, you can add wood ash or lime to raise it and aluminum sulfate or sulfur to lower it.
Using a soil calculator will help you understand exactly how much soil you need overall, so you can create a custom blend of products that’s ideal for your project. Check the soil preferences for anything you’re planning to plant so you can make sure the pH level and soil type are ideal. With the right soil in place, you can help your plants truly thrive.