This publication is part of the Community and School Gardens series.
David Berle and Robert Westerfield
University of Georgia Horticulturists
- Materials
- Slope
- Accessibility
Raised garden beds are a great way to both organize plot space and provide easy access for school and community gardens. To determine the dimensions of raised beds, consider three basic questions:
- What materials will be used to construct the raised beds?
- Is the garden site flat or sloped?
- Will the raised beds be accessible to all of the gardeners?
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
A depth of six to twelve inches is usually sufficient for most plants. If your soil is heavy clay, however, it may be necessary to go deeper. The optimum size for raised garden beds is around four feet wide and eight feet long. This size provides a good balance between planting space and ease of access.
What is the ideal 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'
Why are raised gardens usually only 3 to 4 ft wide? ›
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.
Is 12 inches enough for a raised garden bed? ›
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.
How wide should a raised bed be for tomatoes? ›
Tomato plants should have about 18 inches between them so the roots will have plenty of room to sprawl out. In a 4'x4' raised bed, putting one plant in each corner should allow plenty of space for four plants with plenty of growing space. Plant tomatoes deep as they form additional roots along the stem.
What is the best depth for raised beds? ›
The Best Height for Raised Beds
Keep in mind that beds 18 inches deep or more will have better drainage than shorter beds. While most plants don't need anything deeper than 18 inches, I prefer beds that are two feet deep (24 inches). The extra height is mostly just for the ease and convenience of the gardener.
What is the best layout for a vegetable garden? ›
As a general rule, put tall veggies toward the back of the bed, mid-sized ones in the middle, and smaller plants in the front or as a border. Consider adding pollinator plants to attract beneficial insects that can not only help you get a better harvest, but will also prey on garden pests.
How deep does a raised bed need to be for potatoes? ›
Fingerling potatoes are small, prolific, and tasty, and are therefore especially appropriate for raised beds. Setting up Raised Beds: Raised beds should be at least 12 inches deep and filled to about six inches with a good planter mix and lots of compost.
How many bags of soil do I need for a 2x4 raised bed? ›
Therefore, you'll need six bags of garden soil for a 2x4 raised bed that is 6 inches deep. However, if you plan to make your raised bed deeper, you'll need more soil to fill it. For example, if you want to make your raised bed 12 inches deep, you'll need approximately 1.5 cubic feet of soil per square foot.
Is 10 inches deep enough for raised bed? ›
Consider Drainage
The most popular height for raised beds is 11″. (This is the height of two standard “2 x 6″ boards, which actually measure 1.5″ x 5.5”.) This height provides sufficient drainage for most crops. For best results, there should be another 12″ or more of good soil below the bed.
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).
How far off the ground should a raised garden bed be? ›
A 12-inch raised bed is a great minimum height for growing lots of delicious plants in the kitchen garden. If you want to grow larger vining plants like tomatoes, squash, or zucchini—plants that sprawl and tend to draw a lot of nutrients from the soil as they grow—you might move closer to an 18-inch raised bed.
What is the best size for a raised garden bed? ›
The optimum size for raised garden beds is around four feet wide and eight feet long. This size provides a good balance between planting space and ease of access. However, the size of your raised garden bed will ultimately depend on your available space, gardening needs, and budget.
How far apart should I plant peppers in a raised bed? ›
Quick Guide to Growing Peppers
They grow well in raised beds, containers, and in-ground gardens. Plant them 18 to 24 inches apart in a sunny, well-drained spot. Pepper plants need at least 6-8 hours of sunlight per day. Mix compost or other organic matter into the soil when planting.
Can tomatoes and cucumbers be planted together? ›
However, because they are both heavy feeders, require a lot of moisture and light, and need adequate space around them to promote healthy air circulation, they may compete. In light of this, if you want to grow cucumbers and tomatoes together, it is best to plant them 45 – 60 cm apart and in separate soil if possible.
What should I put in the bottom of my 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.
Is it cheaper to buy or build raised garden beds? ›
A homemade raised garden bed might be cheaper in the short term, but it will cost you far more time and money in the long run.
How far apart should I plant vegetables in a raised bed? ›
The 4-inch spacing is for bush beans and spinach. A 6-inch spacing is needed for Swiss chard, leaf lettuce and parsley. A whole 12-inch square is required for each broccoli, cabbage, cauliflower, corn, eggplant, muskmelon and pepper plant.
What are the disadvantages of raised beds? ›
The cons of raised beds
The soil mix also can be a significant, albeit one-time, expense. Raised beds need water more often since the soil is more exposed to air and dries quicker. Similar to growing in containers, the extra watering can leach nutrients out of the soil quicker than in-ground gardens.
