How much soil is needed for a raised bed? What is a raised bed? What does it do? : Well here we have all the answers that you seek to these questions. Raised-bed gardening is loved because of its myriad benefits in gardening and cultivating vegetables. You can control the soil condition and add specific needs of soil or even add a custom blend of soil for your raised bed.
To avoid wasting the precious blend of soil for a raised bed, you need to know the amount of soil required for the raised bed of a specific size and shape.
Instead of calculating it online, do the maths and know the tricks at your fingertips. I have made it easy for you by giving the formulae as well as solving some for better understanding. You will also learn about the best soil mix, soil, compost, and topsoil that should be used in the raised bed in this read.
What is the Soil for a Raised Bed?
Soil for a raised bed is determined by various factors such as size, shape, and depth. The best soil for raised beds is organic garden soil aka loamy soil. Whatever soil you have in your garden or use for a raised bed, adding amendments is a must. Compost is one of the best amendments for raised-bed gardening.
Even though the organic soil will have all essential nutrients in it, compost will act as a boost to those nutrients. It is okay to add store-bought compost if you don’t have a compost pile in your house. Using store-bought “organic vegetable compost” is a good choice.
What is the Right Blend of Soil for a Raised Bed?
The right blend of soil for a raised bed is Soil, compost, and add-in. The soil blend should have good drainage, nutrients, and proper aeration. The proper ratio is
- 60 percent Topsoil or Organic soil
- 30 percent Compost
- 10 percent Potting mix
You can experiment with the percentage of ingredients added which can be changed according to the plant or vegetable to be added to the raised bed. Garden soil should be avoided in any case because of its heavy texture. To prevent weed growth in the soil, add cardboard at the bottom of the raised bed which provides good drainage and porous soil.
How Much Soil is needed for a Raised Bed?
The soil needed for a raised bed depends on its size and shape. Calculate the soil for raised bed by multiplying the length, width, and height of the raised-bed garden to get the cubic feet of soil to fill the bed. Make sure to measure everything in feet. Here is the simple step to measure and calculate,
Use google maps or walk the lawn at a pace equal to 3 feet to measure the steps below.
Measure the total length of the garden= L
Measure the total width of the garden=W
Measure the total height of the garden=H
Multiply all the three together: Wx Lx H
The answer will be in the total cubic feet of soil needed for the raised bed.
How to Calculate Soil for a Raised bed?
Let us discuss one more way to find out the total soil requirement for a raised bed. Length and width can be measured in feet but depth is measured usually in inches. Use this formula when you know the length and breadth of a raised bed with depth in inches,
Length x Width x (depth in inches to feet) = soil needed in cubic feet.
One inch equals 0.08 feet. The below table will show you the converted measurement from inch to feet.
How much soil is needed for a 3x6 raised bed?
The soil needs a 3x6 feet raised bed, assuming 12 inches of depth, 10 cubic feet of soil, or 12 bags of soil. The calculation is,
12 inches=1 feet
18ft x 1ft=18 cubic feet of soil.
Soil is mostly sold in bags with cubic feet measurements of 1 or 1.5.
18 cubic feet of the soil of 1.5 cubic feet per bag gives 12 bags of soil.
How much soil is needed for a 4x4 raised bed?
The soil needed for a 4x4 feet raised bed, assuming 10 inches depth, 13.28 cubic feet of soil, or 8 bags of soil. The calculation is,
10 inches=0.83 feet
16ft x 0.83ft=13.28 cubic feet of soil.
13.28 cubic feet of the soil of 1.5 cubic feet per bag gives 8 bags of soil.
How much soil is needed for a 4x8 raised bed?
The soil needed for a 4x8 feet raised bed, assuming 10 inches depth, 26.56 cubic feet of soil, or 17 bags of soil. The calculation is,
10 inches=0.83 feet
32ft x 0.83ft=26.56 cubic feet of soil.
26.56 cubic feet of the soil of 1.5 cubic feet per bag gives 17 bags of soil.
How much soil is needed for a 3.5x8 raised bed?
The soil needs a 3.5x8 feet raised bed, assuming 6 inches of depth, 14 cubic feet of soil, or 9 bags of soil. The calculation is,
6 inches=0.5 feet
28ft x 0.5ft=14 cubic feet of soil.
18 cubic feet of the soil of 1.5 cubic feet per bag gives 9 bags of soil.
How much soil is needed for a 3x4x2 raised bed?
The soil needed for a 3x4x2 raised bed is 24 cubic feet of soil.
Total cubic feet = Lx Wx H = 3x4x2 = 24 cu.ft of soil.
If you have raised a bed of the same size in more quantity then simply multiply the answer.
For instance, if you have four similar raised beds at this measurement, the 4(24)= 96 cubic feet of soil in total.
How much soil is needed for a 2x10x3 raised bed?
The soil needed for a 2x10x3 raised bed is 120 cubic feet of soil.
Total cubic feet = Lx Wx H = 2x10x3 = 120 cu.ft of soil.
How to Calculate Soil for Shaped Beds?
Volume calculation differs from the shape of the raised bed. To calculate, you need to know the units and convert them into a common unit. Let us see some shapes and their volume measurement formula,
The very simple measurement to find the volume of a Square or Rectangular shaped bed,
(Volume= W x L x H)
W is the Width of the bed
L is the Length of the bed
H is the Height of the bed
For Circular beds,
- Volume= 3.14* r*r*H
- 3.14 is the pie valve
- r is the Radius of a circle( half the diameter)
- H is the Height of the bed
For Triangular beds,
- Volume= b*h*½
- B is the base area of the bed
- H is the Height Of the bed
For the Hexagonal bed,
- Volume= 3/2(√3) s*s*h
- S is the length of one side of the bed
- H is the height of the bed
What are the Soil Depth and Spacing for a Raised Bed?
The soil depth for a raised bed differs from the plant or vegetable that is grown in the bed. Plants with deep roots need more soil and depth whereas shallow-rooted plants require soil of just a few inches. The need for depth for a succulent plant and a large tree differs so choosing the depth for raised bed should be from the plant or vegetable that is to be grown in that bed.
The spacing for plants and vegetables plays a crucial part in growth and development. For small perennials 15 cams, large perennials 45 cm, flowers 15 cm, vegetables 50 cm, and smaller plants 10 cm is required spacing.
Raised-bed gardening is easy to maintain with maximum productivity. This type of gardening is the best alternative to traditional gardening by eliminating most demerits. Choosing a specific plant or vegetable for a raised bed will ensure the plants get the right nutrients as well. Gardeners don’t have to limit themselves for space and can rather Enjoy Gardening! in a smart way.
1. Can I fill a raised bed with just compost?
No, you can’t fill a raised bed with just compost. Compost with nutrients will make the soil drain away if added more than needed.
2. Should I line my raised garden bed with plastic?
No, avoid lining the garden bed with plastic. Use metal mesh or cardboard to avoid pests and other problems.
3. Do a raised bed need rocks in the bottom layer?
No, a raised bed doesn’t need rocks in the bottom layer.