Raised Garden Bed Dimensions (2024)

Circular 1027-4

This publication is part of the Community and School Gardens series.

Materials

Standard Lumber

Plan ahead if you will be purchasing new lumber. Lumber comes in 8-, 10- and 12-foot lengths, so keep the dimensions of your raised beds to multiples of 2 or 3 feet to minimize waste. For example, if the bed dimensions are 3? x 6?, then 12-foot lumber is perfect. A 4? x 8? bed is most easily built with 8-foot lumber, although 12-foot lumber works, too.

Recycled Materials

If recycled wood is used, the length of the lumber determines the width and length of the bed. Again, the idea is to reduce waste when cutting. There is no set length if the raised bed is constructed of rock or blocks, but keep in mind that gardeners will need to easily get around the entire bed.

Wall Thickness

Wall thickness will depend on the material used and should be incorporated into the dimensions of each raised bed and the overall layout plan. For example, 8-inch-thick recycled concrete blocks will take up additional space and require a longer distance to reach across. Lumber that is only 1 inch thick will require a vertical support approximately every 4 feet.

Slope

The soil in raised beds should be flat, which means the constructed frame should be level when installed. To avoid excessive excavation when the site is sloped, install the raised beds with the shortest dimension perpendicular to the slope, like stair steps.

Accessibility

Width

One major goal of raised beds is to alleviate the need for gardeners to step into them. This means gardeners should be able to easily access the bed from all sides. Plan raised beds that are 3 feet wide for children and 4 feet wide for adults. If providing wheelchair access, plan raised beds that are 2 feet wide for children and 3 feet wide for adults.

Length

The length of a bed is not as critical as the width, but bear in mind that very long raised beds can be a hassle to walk and work around. While the length of a raised bed will be partly determined by available materials, keep in mind that the cost of lumber increases noticeably if the length is more than 12 feet.

Height

The higher the bed, the more imported soil will be required. This will add to the cost and labor involved in the garden project. In some situations, raised planters can be built that are 10 inches deep, but elevated off the ground with legs or blocks. This is ideal for wheelchair access and also saves on imported soil. However, the bottom must be strong enough to both hold the weight of the soil when it is wet and still allow water to drain. A few other considerations to keep in mind:

Most garden crops need at least 10 inches of soil to thrive. If the raised bed height is lower than this, till the existing soil below the raised bed.
If the raised bed is on top of a hard surface, the minimum recommended height of 10 inches may not be deep enough for some crops, like potatoes.
Young children need beds closer to the ground.
For wheelchair access, beds should be 24 inches tall.
A bed that is 36 inches off the ground helps avoid excessive bending over.
Consider having a mix of bed heights to accommodate different gardeners.

Paths

If possible, beds should be laid out in a pattern that allows access to one central path that stretches from one end of the garden to the other. A wider central path provides room for gathering and access for everyone. If it is a very large garden, more than one such path will prove useful. To provide access for a small truck, make this path at least 10 feet wide.

Gardeners also need paths to move from bed to bed on foot and sometimes in a wheelchair. At an absolute minimum, 12-inch paths will be needed between raised beds. This width works if the space is tight and there won?t be a lot of gardeners working at the same time, but to allow more comfortable access, 18- to 24-inch paths are ideal. For paths to provide enough room for carts, wheelbarrows and wheelchairs, allow 4 feet between beds.

Orientation

Orientation of raised beds is not usually a problem if adequate space is left between beds for access. Tall crops will shade lower crops behind them if both are planted in the same bed. Tall crops will shade lower crops in nearby beds if they are planted on an east-west orientation and if the beds are close together. If possible, lay out beds in a north-south direction.

Irrigation

Consider the irrigation system when you are planning the layout of raised beds. Drip irrigation is much easier to install when beds are in an orderly pattern, preferably a straight line. Overhead sprinklers can be placed and adjusted to cover almost any garden layout, but they work best if raised beds are in a circular, square or rectangular pattern. Hand watering will require dragging a hose throughout the garden; uniform bed spacing and layout will make this task easier.

Status and Revision History
Published on Feb 27, 2013
Published with Full Review on Aug 31, 2016
Published with Full Review on Sep 30, 2019
Published with Full Review on Dec 14, 2022

FAQs

Raised Garden Bed Dimensions? ›

An ideal size for a raised bed is 3 to 4 feet wide with the length to suit the space available. It is most often rectangular in shape and generally 8 to 12 feet long. The bed may be as much as a foot deep, depending on the type of plants being grown.

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What is a good size for a raised garden bed? ›

As a general rule, raised beds are typically between 1.5 and 4 feet wide and between 4 and 10 feet long. Common raised bed garden sizes include: 4' x 4' 2' X 8'

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How deep should a raised garden bed be? ›

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.

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Is 2 feet wide enough for raised bed? ›

The ideal width for a raised garden bed is around four feet. This width allows easy access to the plants from both sides of the bed, while still providing enough planting space for a variety of crops.

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Is 12 inches enough for a raised garden bed? ›

Raised beds don't have to be very deep to be effective. Eight to 12 inches is usually adequate. If drainage is a problem, or if the plants you are growing prefer drier soil, the bed could be taller and filled with a porous growing medium. Vegetable beds, however, should be at least 12 to 18 inches deep.

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

As a rule of thumb, a 4'x8' raised bed that is 6 inches deep requires approximately 8 bags of soil while a 4'x8' raised bed that is 12 inches deep requires approximately 16 bags of soil.

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What do I put on the bottom of a raised garden bed? ›

Cardboard and Wood Chips: Layering cardboard at the bottom of your raised bed is an effective, cost-efficient way to suppress weeds. It eventually breaks down, enriching the soil with carbon. Wood chips can be added on top of the cardboard as an additional layer for weed control and moisture retention.

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How deep should raised 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.

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Which vegetables grow best in raised beds? ›

Most garden vegetables will grow well in raised beds. Try growing lettuce, greens, radishes, and strawberries. Bush type vegetables, such as tomatoes, cucumbers, and beans also do well in raised beds. You can install trellises for vegetables that need support, like some tomatoes and beans.

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How deep does a raised bed need to be for peppers? ›

Carrots, radishes and peppers thrive with 12 inches or more. Medium-rooting vegetables like kale, cucumbers, and zucchini love at least 18 inches. A 2-foot bed is ideal for these types of vegetables, as well as fruits that grow on bushes like blueberries, strawberries, and raspberries.

What is the best height for a raised bed? ›

If the raised bed is on top of a hard surface, the minimum recommended height of 10 inches may not be deep enough for some crops, like potatoes. Young children need beds closer to the ground. For wheelchair access, beds should be 24 inches tall. A bed that is 36 inches off the ground helps avoid excessive bending over.

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How shallow can a raised bed be? ›

The minimum required depth depends on the plant. But on average, a raised garden bed should accommodate about 20 inches of soil for the roots of flowers and vegetables.

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Can raised garden beds be too tall? ›

The best height for a raised garden bed really depends on what you intend to grow in them, and how you intend to use yours, but expect it to be a minimum of 8in deep (for 6in soil depth) up to 37in depth (for a 36in soil depth). The most usual height for a raised bed is around 11in (for soil depth of around 8 to 10in.

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Which vegetables need deep soil? ›

Pumpkins, winter squash, and watermelons have deep roots that go down 24 to 36 inches or more. Tomatoes, artichokes, okra, and sweet potatoes also have deep roots.

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How big is too big for a raised garden bed? ›

The maximum width you would want for a raised bed is about four feet wide, and that would only be for beds that you're able to access from all four sides. Anything beyond four and a half to five feet typically makes plants in the middle of the bed too difficult to reach (unless you have very long arms).

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What is the best size for a vegetable garden? ›

It is easy to bite off more than you can chew when you are a first-time vegetable gardener. As a rule of thumb, you should start small then add if needed. A good starting size for a garden would be between 75 and 100 square feet.

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What is the best layout for a raised bed vegetable garden? ›

For home vegetable gardens, narrow beds up to four feet wide are best, as this enables the gardener to reach into the center of the bed. This avoids the requirement for digging and disturbing the existing soil structure, and soil compaction is reduced as there is no need to walk on it.

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How deep should a raised bed be for tomatoes? ›

What can you grow in an 18-inch-deep garden bed? Eighteen inches is the minimum height needed for plants like tomatoes, cucumbers, squash, zucchini, and kale—plants that have a bigger root base and need more nutrients and space to spread out. This height also allows for better drainage.

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