How Much Soil Do Raised Garden Beds Need (2024)

When it comes to gardening, raised beds have become increasingly popular due to their benefits such as better drainage, improved soil quality and easy maintenance. However, the question arises: how much soil volume do you need for a raised bed?

In this article, we will explore the answer to this question and show you how to calculate the amount of soil needed for raised beds. We will also look at the best soil for a raised bed garden to help plants grow. By looking at these two topics, we hope to equip you with all the necessary information to make your raised-bed gardening experience a success.

What is a Raised Bed and Why is it Useful for Gardening?

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A raised bed, sometimes referred to as a garden bed or a planting bed, is a garden technique that involves creating a garden area - one that is typically rectangular or square-shaped - that is raised above ground level. A raised bed is usually framed with wood, stone, concrete blocks or other materials and filled with soil for planting. The height of a raised bed can vary and can be customized to the gardener's preference.

There are several advantages to using a raised bed for gardening. Because a raised bed is above ground level, it allows for better drainage, prevents soil compaction and improves air circulation. Raised beds are also easier to maintain, and they provide better control over the soil quality. They also offer better accessibility and make it easier to manage a garden.

If you're starting a raised garden bed buildup, you will need the following materials: wood boards, corner brackets, screws, drill, soil, compost and topsoil. Other materials that can be used include concrete blocks, stones, bricks or cinder blocks. Before building your raised bed, consider the dimensions and location of your garden bed and ensure the materials you use are suitable for the location.

How Much Soil Do Raised Garden Beds Need (2)

How Much Soil Do I Need for My Raised Bed?

Many gardeners have never even considered the possibility that a garden can have too much or not enough soil - but it can. Having too much soil causes excessive water retention that can lead to root rot, and it can lead to the plant "spilling" out of the bed. On the other hand, not enough soil means the plants are harder to see, and it becomes more difficult to grow plants with larger root systems.

There are several ways we can approach the soil calculations you'll need for a raised bed garden. Here are some of the most common methods.

Using a Soil Calculator

Using a soil calculator is a quick and easy way to determine the amount of soil you need for your raised bed. Simply input the dimensions of your raised garden bed along with the desired depth of soil and the soil calculator will automatically tell you how much soil you need.

Here at Frame It All, we have a Soil Calculations page with a chart that gives you the recommended soil amount (in cubic feet) for all our raised bed designs. If you have a garden bed size or design that is not listed, consider the method below to calculate the soil needed for your raised beds.

Using the Area Method

Another way to calculate how much soil you need is by using the area method. Simply multiply the length and width of your bed together, then divide that number by 27 (the cubic feet in a cubic yard). This will give you the number of cubic yards of soil you need, assuming an average soil depth of one foot.

For example, if your raised bed is five feet long by four feet wide (20 square feet), you will need approximately 0.74 cubic yards of soil. If your length and/or width measurements are in inches, remember to divide them by 12 to convert to feet before doing the calculation.

Factors That Affect Soil Volume in Raised Beds

When calculating the amount of soil you need for your raised bed, several factors come into play such as the size of the bed, the vegetable garden bed depth, the type of plants you want to grow, and the type of soil you want to use. Some plants require more soil depth than others, and soil volume can also be affected by the type of soil you use.

If you're not sure how deep a raised garden bed should be, the rule of thumb is 8-12 inches for most vegetables. However, if you plan to grow root crops such as carrots or beets, 12-18 inches is recommended. You may also need additional soil depth if you're using a Lasagna garden bed method or a deep mulch gardening approach.

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What Type of Soil is Best for Raised Beds?

Recommended Soil Mix for Growing Vegetables and Flowers in Raised Beds

The best soil mix for raised beds is one that is rich in organic matter, drains well and is nutrient-dense. A good soil mix can be made using a combination of one-third compost, one-third topsoil and one-third potting soil. This mixture provides a suitable environment for plants to grow while also retaining moisture and providing nutrients, which will allow you to enjoy the benefits of a raised garden bed to the fullest.

If you cannot make a soil mix, you can purchase a pre-made organic soil mix specifically designed for raised beds. For best results, it's important to choose an all-natural, organic potting soil that is free of synthetic fertilizers and pesticides. A good garden soil mix should also include perlite, vermiculite and other materials to promote drainage and aeration.

Additionally, you can add slow-release fertilizers, compost tea and a mulch layer to your raised bed soil mix to ensure that your garden is adequately nourished.

Using Compost and Topsoil in Your Raised Bed

Compost is a great addition to a raised bed garden as it provides organic matter which is essential for plant growth. Topsoil, on the other hand, is the top layer of soil that is rich in nutrients and minerals and is also important for plant growth. Using a combination of compost and topsoil is an effective way to ensure your raised bed has the necessary nutrients for your plants to thrive.

Pros and Cons of Using Peat-based Soil Mixes in Raised Beds

Peat-based soil mixes are commonly used in raised beds as they help retain moisture, provide good drainage and are pathogen-free. However, these mixes can be expensive and may not be environmentally friendly. Peat is a non-renewable resource, and its harvesting can have negative effects on the environment. It is also on the acidic side, which some plants won't respond well to. Therefore, it is essential to consider the pros and cons of peat-based soil mixes before using them in your raised bed garden.

How to Fill a Raised Bed with Soil?

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Buying Soil in Bags or Bulk: Pros and Cons

When it comes to buying soil for your raised bed, you can either buy it in bags or in bulk. Buying soil in bags is convenient as it does not require any measuring or calculations. However, it can be expensive and time-consuming. Buying soil in bulk, on the other hand, is cost-effective but requires some effort as you will need to transport the soil to your garden.

In any case, the way you buy your soil for raised beds will depend on your budget, the availability of soil in bulk and personal preference.

Soil Mixes for Raised Beds

Many soil mixes are available for different types of plants. Before purchasing any soil mixes for your raised bed, it is important to do research and find out which type of soil mix would be most suitable for your garden.

Calculating the Amount of Soil You Need for Your Raised Bed

Calculating the amount of soil you need for your raised bed is an important step as it helps to ensure that you do not run short of soil or end up with too much soil. Once you have determined the cubic feet of soil required, you can calculate the number of bags or cubic yards of soil you need for your raised bed.

How Much Soil Volume is Necessary for a Specific Raised Bed Size?

The amount of soil needed for a specific raised bed size varies depending on the dimensions of the garden bed and the desired soil depth. As a rule of thumb, a 4' x 8' raised bed that is six inches deep requires approximately eight bags of soil while a 4' x 8' raised bed that is 12 inches deep requires approximately 16 bags of soil.

Buy Your Garden Bed Equipment From Frame It All

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Bored with the same old garden, but can't find a way to make a change? Frame it All has the perfect solution: create your own customized raised garden bed setup. Not only do you have a large selection of sizes and styles to choose from, but our patented interlocking panels also provide optimal drainage and increased aeration for healthier soil. Plus, because of its elevated design and included protective cover, your raised beds are protected from unwanted pests that might otherwise wreak havoc on your flowers or veggies.

With Frame It All's raised bed system, you not only get protection and convenience but also complete control over how the bed is configured. Get creative by adding trellises or separators and dividers, add extra height or utilize corner pieces to form inspiring shapes. The possibilities are endless, allowing you to tailor-make your dream outdoor living space without hiring an expensive contractor.

Start building the perfect garden now with Frame It All's one-of-a-kind raised bed systems available for purchase online today!

How Much Soil Do Raised Garden Beds Need (2024)

FAQs

How Much Soil Do Raised Garden Beds Need? ›

If you're not sure how deep a raised garden bed should be, the rule of thumb is 8-12 inches for most vegetables. However, if you plan to grow root crops such as carrots or beets, 12-18 inches is recommended.

How much soil to fill a raised garden bed? ›

This is simply the length times the width of your garden bed. Then, to get the total cubic feet of each raised bed, simply multiply the square feet of your garden's footprint by the height of your raised bed garden. This provides the total cubic feet of garden space that must be filled with soil.

How full should you fill a raised garden bed? ›

Filling the Raised Garden Beds

For beds six to 12 inches deep, fill completely with soil. For deeper beds, it's sometimes helpful to add other materials to take up space and reduce the overall amount of soil, but it depends on your preference and soil availability.

How deep should a raised garden bed be for tomatoes? ›

Tomatoes should ideally be grown in a raised bed that's at least 15 to 18 inches deep. Many of my clients in Houston are successfully growing tomatoes in 12-inch deep raised garden beds, but their plants tend to be a little stunted compared to plants in deeper beds.

How often do you change soil in raised beds? ›

Ideally, we think it's best to consider replenishing the soil between each season i.e. after every Autumn/Winter and Spring/Summer harvest; however, if you can only do it once a year, that's alright too.

How many cubic feet are in a 40 lb bag of soil? ›

A 40 pound bag of topsoil usually contains about 0.75 Cubic Feet of soil. There are 25.71404638 Dry Quarts in a Cubic Foot, so a 25 quart bag of potting soil would equal approximately 1 Cubic Foot. If you are filling pots, you will be fine. If you are spreading it on a lawn of any significant size, it will disappear.

How deep should soil be in raised bed for vegetables? ›

Vegetable Beds: On the other hand, when it comes to vegetable beds, the bed must be approximately 12 to 18 inches deep to ensure adequate depth for the roots of your plants. This is especially important if your raised bed is placed on cement or the patio, which will inhibit roots from growing deeper into the ground.

How to fill raised beds cheaply? ›

To start, lay down sheets of cardboard or newspaper for weed suppression and then fill the raised bed structure halfway up with alternating layers of nitrogen-rich materials (like kitchen scraps and grass clippings) and carbon-rich materials (like wood chips and dried autumn leaves).

Should I put rocks in the bottom of my raised garden bed? ›

A: You should avoid putting rocks in the bottom of your garden bed. A common myth is that this will improve drainage. Instead, this can actually increase water saturation levels as well as allow gravel to mix in with your soil, which can prove very difficult to remove later on.

Is it cheaper to buy or build raised garden beds? ›

On average, a DIY raised bed constructed from wood will cost $25 to $50 per square foot. To have a wooden raised bed constructed and installed for you, budget for at least $100 per square foot. (Find a kitchen garden company in your area.)

Do tomatoes like top soil or potting soil? ›

Good potting soil of any type is all you need to grow tomatoes and other vegetables in pots.

Do tomatoes grow better in pots or in the ground? ›

In general, determinate tomatoes tend to do better in pots, so look for those. It's also possible to grow indeterminate tomatoes in containers, of course, as long as you provide enough support and soil volume.

Do tomatoes grow well in raised beds? ›

Like most vegetables, tomatoes like well-draining, nitrogen-rich soil with a pH of around 6.5. Growing in a raised bed allows you to create the perfect conditions for your tomato plants, rather than trying to amend your native soil to get just-right conditions.

Is it OK to use potting soil for raised beds? ›

Whether deep or shallow, raised beds give a gardener a way to create ideal soil conditions on an even larger scale. While potting mix alone is too light for use in raised beds, creating a 50:50 blend of potting mix and Miracle-Gro® All Purpose Garden Soil will give just the right balance.

How many bags of soil do I need for a 4x8 raised bed? ›

A 40 qt bag is 1.3(and some) cu ft. 4'x8'x[height] is the volume of your bed. If you assume the height is 1', your volume is 32 cu ft. Divide by 1.3 per bag, and I think you need 24.6 40qt bags, so 25 bags.

Can you reuse soil in a raised bed? ›

Yes, you can reuse a raised bed! You'll just need to refresh the nutrients in the soil to replace all the nutrients used up last year.

What do you put in the bottom of a raised garden bed? ›

Layer the bottom with cardboard or newspaper as a weed barrier, which will decompose over time. Then, use a mix of yard waste, leaves, grass clippings, and kitchen scraps layered with soil and compost.

How to fill space in a raised garden bed? ›

The smaller pieces are placed on top of the larger pieces to fill space, such as branches and sticks, and then grass clippings, leaves and kitchen scraps. Compost and topsoil are on the top two layers for your raised garden bed so you can start planting as the organic matter beneath decomposes.

Do you put topsoil in raised beds? ›

Filling Raised Beds

We fill our beds with half compost and half topsoil. It's economical, the soil gives the plants' roots something to hold onto, and the compost feeds the plants.

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