Raised garden beds are incredibly popular for growing vegetables, herbs, and flowers. They offer many benefits over traditional in-ground gardening, including better drainage warmer soil temperatures and easier access.
When constructing a raised bed, one of the most important considerations is sizing it correctly. The optimal width, length, and height will depend on your specific needs and goals. In this article, we’ll break down the ideal dimensions so you can build the perfect raised beds for your garden.
Factors to Consider
There are several factors to think about when determining the ideal size for your raised beds:
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What you intend to grow – Root crops, vining plants, or lettuces will all require different bed shapes and depths.
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Accessibility – Beds need to be narrow enough to comfortably reach across for planting, weeding, and harvesting.
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Available space – Make sure to map out your garden area and arrange beds efficiently.
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Materials – Standard lumber lengths and material costs will impact bed dimensions.
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Aesthetics – Beds can become design features, so consider how they’ll enhance your overall garden layout.
Recommended Width
The optimal width for a raised bed is 4 feet if accessing it from both sides. This allows you to comfortably reach the center from either side for tending the plants.
If the bed will be against a wall or fence the ideal width is just 2 feet since access is only from one side. Any wider than 2 feet and the center area becomes difficult to reach.
For children’s gardens, aim for a maximum of 3 feet wide if accessed from both sides.
Recommended Length
Raised beds can technically be any length, but long beds become difficult to navigate. It’s better to use shorter lengths with multiple beds rather than few very long beds.
A common length is 8 feet, which coordinates well with standard lumber sizes. Even 10-12 feet is manageable. Just avoid extremes like 20+ feet in length.
Recommended Height
Most vegetables do fine in just 10 inches of soil depth. But deeper beds of 18-24 inches allow you to grow root crops, give plants more root room, and retain more moisture.
For gardens with poor drainage, do at least 18 inches. For wheelchair accessible gardens, construct beds to be about 30 inches tall.
Ideal Raised Bed Size Examples
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4 feet x 8 feet x 12 inches – Great all-purpose bed for lettuces, herbs, brassicas.
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2 feet x 10 feet x 6 inches – Good for green beans, tomatoes supported by a trellis.
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3 feet x 12 feet x 18 inches – For root crops like carrots and potatoes.
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4 feet x 4 feet x 24 inches – Can grow a diversity of vegetables in a small space.
Keep these raised garden bed dimensions in mind as you plan out your vegetable garden. Consider the plants you want to grow, your space constraints, accessibility, and materials available when deciding on the ideal sizes. With properly sized raised beds, you’ll maximize growing area and enjoy easy access for planting, maintaining, and harvesting your garden!
How deep should a raised bed be for tomatoes?
Tomatoes are heavy feeders, and indeterminate tomatoes, or the vining type, either spread out horizontally or climb as they produce fruit. All that means that their roots need lots of soil depth to find nutrients and build support structures for the heavy plant.
Tomatoes should ideally be grown in a raised bed thats 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.
In my first ever attempt to grow tomatoes, I planted them in a 6-inch raised bed. The only reason the plants grew is because their roots were able to push into the native soil beneath the bed (even though it was heavy in clay and not ideal for a vegetable garden). I never ended up getting much fruit from these plants.
How deep does a raised bed need to be for herbs?
Many of the herbs you might want to grow in your garden have shallow root systems that only need about 6 inches of raised bed or container depth. These herbs include oregano, rosemary, mint, sage, basil, and thyme. These herbs are ideal for growing in pots and containers, which isnt to say that you cant also plant them in deeper raised beds.
The exception here would be herbs in the carrot family. Cilantro, parsley, and dill actually grow a little taproot like a carrot. They prefer more space to dig their roots down and do better in a container or raised bed thats at least 12 inches tall.
(Learn more about growing herbs in containers.)
9 Beginner Raised Bed Garden Mistakes to Avoid
FAQ
What is a good size for a raised garden bed?
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.
What vegetables should not be grown in a raised bed?
- Potatoes.
- Asparagus.
- Artichokes.
- Rhubarb.
- Corn.
- Wheat.
- Rice.
- Winter Squash.
What do you put in the bottom of a raised garden bed?
You can line the bottom of your raised garden bed with cardboard and newspaper to deter pests and weeds.