How Much Soil Do I Need for a Raised Garden Bed?

Many people are interested in raised gardens because of the myriad of benefits they offer. Some of those benefits include more control over soil type and conditions, ease of planting using the square foot method, and fewer weeds.

Filling raised beds with soil is necessary for planting, but it's also important to calculate the amount of soil needed in order to avoid waste and save money.

Calculating the volume of soil needed for raised beds

Vego Garden's soil cost calculator can help you figure out exactly what you need based on the raised bed shape, height, width - and for round beds, diameter.

Here are some more details.

Before going into the formula, you need to know what units of measure are needed. For the calculation, you need to find the appropriate dimensions of the bed and then convert them into a common unit. For example, if the volume measurement is in feet, then convert the appropriate measurements of the bed into feet first.

Square/rectangle soil volume of raised beds

The formula for soil volume in a rectangle bed is very simple, involving only three measurements. You can also refer to the product page for the volume of each configuration in a standard kit.

V = L x W x H

• V stands for the volume of the soil you need to fill.
• L is the length of the raised bed.
• W is the width of the raised bed.
• H refers to the height of the raised bed.

1. Measure the length, height and width of the bed. Remember to convert the measurements to the same unit. For example, if your bed is 17 inches, divide by 12 to get 1.4 feet.

2. Multiply the measurements together.

3. Divide number by 27 to convert it to cubic yards, as bulk soil is often sold by the yard.

Circular raised beds

To calculate the area of a circular raised bed, you need to know the bed’s radius and height, which you can check on the product page. The radius is half the diameter of the circle. Square the radius, and then multiply by 3.14. Finally, multiply the amount by the height to get the volume.

V = r^2 x 3.14 x H

Geometric beds

The formula below is for a hexagonal raised bed, when the bed is a regular hexagon (meaning the sides are all the same length.)

V= 3/2 (√3) S2 x H

• V is the total soil volume
• S equals the length of one side of the regular hexagon
• H equals the height of the bed

Soil depth for raised beds

The amount of soil required also depends on the variety of plants that you wish to grow. Deep-rooted plants require more soil, while others need shallow soil to cover the roots. 

The following plants have 12-18 inch roots:

• Garlic, onions, chives
• Lettuce, brussels sprouts, spinach
• Corn, cabbage, radishes 
• Strawberries 

The following plants have 18-24 inch roots:

• Beans, peas
• Cantaloupes, squash, eggplants
• Carrots, turnips, beets
• Potatoes

Below are plants with deeper systems of 24-36 inch roots:

• Artichokes, asparagus
• Parsnips, rhubarb
• Sweet potatoes, pumpkins
• Watermelons 

Raised garden beds have an advantage in that you can grow plants in half of the normally required depth, so you can plant almost all the items in the above list in our 17-inch and 32-inch beds. You can mix and match the vegetables according to your taste and preferences, making sure to space them out accordingly.

What is mulch and why do I need it?

Mulch is a layer covering the soil, often made of organic material. It is commonly made of shredded bark, but alternatives can include grass clippings, leaves, woodchips or straw. 

Mulch is used to improve the aesthetic appearance of the garden bed, as well as protect the soil by keeping it moist and inhibit the growth of weeds. Organic mulch improves soil quality and richness.

It's important to supplement the soil in your garden bed to make sure that it isn't depleted of nutrients. Adding organic matter to the soil is essential to maintain the health of the soil. You can add chopped leaves to the soil in the fall, and add compost in the spring. Consider starting a compost pile so you can simultaneously reduce waste and the amount of fertilizer needed.

The right blend of soil for a raised bed

To achieve good drainage, use pre-mixed soil. Vegetables, fruits and herbs require a nutrient-rich, lightweight soil mixture that is generally composed of the following ratios:

• 60% quality soil
• 30% composted material
• 10% soilless add-ins

You can experiment with the ratio to see which blends are best for different crops. Garden soil should not fill the whole bed, as it is too heavy for good drainage. You should add half potting soil to the mix for best results.

How to prevent weeds

You should add material to the bottom of your bed to prevent weed growth. Cardboard can be used as it is a cheap, readily available solution that creates a weed barrier while still being porous enough to maintain good drainage. However, it can degrade quickly. If you want a more permanent solution, you can use landscape fabric or hardware cloth to stop both weeds and pests like gophers and moles.

Soil required for Vego Garden metal raised beds

Vego Garden 17" Tall 4 in 1:

Configuration	Width (ft)	Length (ft)	Height (in)	Cubic Feet	Cubic Yard
C3535	3.5	3.5	17	17	0.6
C2050	2	5	17	14	0.5
C2035	2	3.5	17	10	0.4
C2020	2	2	17	6	0.2

 

Vego Garden 17" Tall 6 in 1:

Configuration	Width (ft)	Length (ft)	Height (in)	Cubic Feet	Cubic Yard
C3550	3.5	5	17	25	0.9
C2065	2	6.5	17	18	0.7
C3535	3.5	3.5	17	17	0.6
C2050	2	5	17	14	0.5
C2035	2	3.5	17	10	0.4
C2020	2	2	17	6	0.2

 

Vego Garden 17" Tall 9 in 1:

Configuration	Width (ft)	Length (ft)	Height (in)	Cubic Feet	Cubic Yard
C3565	3.5	6.5	17	32	1.2
C2080	2	8	17	23	0.8
C5050	5	5	17	35	1.3
C2065	2	6.5	17	18	0.7
C3550	3.5	5	17	25	0.9
C3535	3.5	3.5	17	17	0.6
C2050	2	5	17	14	0.5
C2035	2	3.5	17	10	0.4
C2020	2	2	17	6	0.2

 

Vego Garden 17" Tall 10 in 1:

Configuration	Width (ft)	Length (ft)	Height (in)	Cubic Feet	Cubic Yard
C2595	2.5	9.5	17	34	1.2
C4080	4	8	17	45	1.7
C2580	2.5	8	17	28	1.0
C4575	4.5	7.5	17	48	1.8
C2575	2.5	7.5	17	27	1.0
C5565	5.5	6.5	17	51	1.9
C4065	4	6.5	17	37	1.4
C2565	2.5	6.5	17	23	0.9
C6060	6	6	17	51	1.9
C2560	2.5	6	17	21	0.8

 

Vego Garden 32" Extra Tall 4 in 1:

Configuration	Width (ft)	Length (ft)	Height (in)	Cubic Feet	Cubic Yard
C3535	3.5	3.5	32	32.67	1.21
C2050	2	5	32	26.67	0.99
C2035	2	3.5	32	18.67	0.69
C2020	2	2	32	10.67	0.4

 

Vego Garden 32" Extra Tall 6 in 1:

Configuration	Width (ft)	Length (ft)	Height (in)	Cubic Feet	Cubic Yard
C3550	3.5	5	32	47	1.7
C2065	2	6.5	32	35	1.3
C3535	3.5	3.5	32	33	1.2
C2050	2	5	32	27	1
C2035	2	3.5	32	19	0.7
C2020	2	2	32	11	0.4

 

Vego Garden 32" Extra Tall 9 in 1:

Configuration	Width (ft)	Length (ft)	Height (in)	Cubic Feet	Cubic Yard
C3565	3.5	6.5	32	61	2.2
C2080	2	8	32	43	1.6
C5050	5	5	32	67	2.5
C2065	2	6.5	32	35	1.3
C3550	3.5	5	32	47	1.7
C3535	3.5	3.5	32	33	1.2
C2050	2	5	32	27	1.0
C2035	2	3.5	32	19	0.7
C2020	2	2	32	11	0.4

 

Vego Garden 32" Extra Tall 10 in 1:

Configuration	Width (ft)	Length (ft)	Height (in)	Cubic Feet	Cubic Yard
C4080	4	8	32	63	2.3
C2595	2.5	9.5	32	85	3.2
C2580	2.5	8	32	53	2.0
C4575	4.5	7.5	32	90	3.3
C2575	2.5	7.5	32	50	1.9
C5565	5.5	6.5	32	95	3.5
C4065	4	6.5	32	69	2.6
C2565	2.5	6.5	32	43	1.6
C6060	6	6	32	96	3.6
C2560	2.5	6	32	40	1.5

 

Vego Garden Special Shapes:

Configuration	Width (ft)	Length (ft)	Height (in)	Cubic Feet	Cubic Yard
L-Shaped Standard	5.5	5.5	17	30	1.1
L-Shaped Large	7	7	17	41	1.5
U-Shaped Standard	5.5	8.5	17	51	1.9
U-Shaped Large	7	8.5	17	62	2.3
U-Shaped Jumbo	7	11.5	17	92	3.4
Cascading Standard	2	3.5	32	70	2.6