How to Build a Raised Garden Bed

Planning, Building, and Planting a Raised Garden Bed

January 10, 2020
raised-garden-bed

Learn how to easily build your own raised garden bed!

Crestock

Raised garden beds are fairly easy to construct, even easier to maintain, and offer myriad benefits for your garden (and you)! Here’s how to build a raised garden bed in your backyard, as well as some advice on using the right wood and soil.

Raised beds are an easy way to get into gardening! Whether you purchase a kit or build your own, there are many great reasons for using raised bed gardening.

What Is a Raised Garden Bed?

A raised garden bed (or simply “raised bed”) is a large planting container that sits aboveground and is filled with soil and plants. It is a box with no bottom or top—a frame, really—that is placed in a sunny spot and filled with good-quality soil—to become a source of pride and pleasure, and a centerpiece of the garden.

Why Should I Build a Raised Garden Bed?

Raised beds have many benefits. Here are a few reasons why you should consider using one:

  • Garden chores are made easier and more comfortable thanks to less bending and kneeling. Save your knees and back from the strain and pain of tending the garden!
  • Productivity of plants is improved due to better drainage and deeper rooting.
  • Raised beds are ideal for small spaces where a conventional row garden might be too wild and unwieldy. Raised beds help to keep things organized and in check.
  • Planting in a raised bed gives you full control over soil quality and content, which is especially important in areas where the existing soil is rocky, nutrient-poor, or riddled with weeds.
  • Raised beds allow for a longer growing season, since you can work the soil more quickly in the spring in frost-hardened regions, or convert the bed into a cold frame in the fall.
  • Fewer weeds are seen in raised beds thanks to the bed being elevated away from surrounding weeds and being filled with disease- and weed-free soil.
  • Raised beds allow for easier square-foot gardening and companion planting.

Learn more about the benefits of raised garden beds

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Choosing the Right Wood for Raised Beds

Many people are concerned about the safety of their wood frame. First, rest assured that CCA pressure-treated wood is banned, as it was known to leach arsenic. To ensure that the wood lasts, there are several options:

  • Regular pressure-treated lumber sold today has a mixture of chemicals applied to prevent the moist soil and weather from rotting it. Although pressure-treated wood is certified as safe for organic growing, some people have reservations about using it, and there are various eco-friendly alternatives. 
  • More expensive woods, such as cedar, contain natural oils which prevent rotting and make them much more durable. They are more expensive to buy, but they will last many more years.
  • Choosing thicker boards can make the wood last longer. For example, 2-inch-thick locally sourced larch should last 10 years, even without treatment.
  • Avoid using railroad ties, as they may be treated with creosote, which is toxic.

Alternatives to wood include concrete blocks or bricks. However, keep in mind that concrete will increase the soil pH over time, and you will have to amend the soil accordingly to grow your best garden.

How Big Should Your Raised Bed Be?

  • First, you need a location that has level ground and gets the right amount of sunlight (6 to 8 hours per day). This should narrow down your options a bit.
  • In terms of bed size, 4 feet is a common width. Lumber is often cut in 4-foot increments, and you also want to be able to access the garden without stepping into the bed. Making the bed too wide will make it difficult to reach the middle, which makes weeding and harvesting a pain.
  • Length isn’t as important. Typical plots are often 4 feet wide by 8 feet long or 4 feet wide by 12 feet long. Make your bed as long as you like or build multiple raised beds for different crops.
  • The depth of the bed can vary, but 6 inches of soil should be the minimum. Most garden plants need at least 6 to 12 inches for their roots, so 12 inches is ideal.

Preparing the Site for a Raised Bed

  • Before you establish the bed, break up and loosen the soil underneath with a garden fork so that it’s not compacted. Go about 6 to 8 inches deep. For improved rooting, some gardeners like to remove the top layer (about a spade’s depth), dig down another layer, and then return the top layer and mix the soil layers together.
  • If you’re planning to put your raised bed in a space currently occupied by a lawn, lay down a sheet of cardboard, a tarp, or a piece of landscaping fabric to kill off the grass first. After about six weeks (or less, depending on the weather), the grass should be dead and will be much easier to remove.

Building a Raised Garden Bed

  • To support timber beds, place wooden stakes at every corner (and every few feet for longer beds). Place on the inside of the bed so that the stakes are less visible.
  • Drive the stakes about 60% (2 feet) into the ground and leave the rest of the stakes exposed aboveground.
  • Ensure that the stakes are level so that they’re in the ground at the same height, or you’ll have uneven beds.
  • Set the lowest boards a couple inches below ground level. Check that they are level.
  • Use galvanized nails (or screws) to fix the boards to the stakes.
  • Add any additional rows of boards, fixing them to the stakes, too.

Check out our video on how to build raised beds for your vegetables:

Soil for Raised Garden Beds

The soil blend that you put into your raised bed is its most important ingredient. More gardens fail or falter due to poor soil than almost anything else. 

  • Fill the beds with a mix of topsoil, compost, and other organic material, such as manure, to give your plants a nutrient-rich environment (see recipes below). Learn more about soil amendments and preparing soil for planting.
  • Note that the soil in a raised bed will dry out more quickly. During the spring and fall, this is fine, but during the summer, add straw, mulch, or hay on top of the soil to help it retain moisture.
  • Frequent watering will be critical with raised beds, especially in the early stages of plant growth. Otherwise, raised beds need little maintenance.

Raised Bed Soil Recipe

For a 4x8-foot raised bed:

  • 4 bags (2 cubic feet each) topsoil (Note: Avoid using topsoil from your yard, as it may contain weeds and pests.)
  • 2 pails (3 cubic feet each) coconut coir (to improve drainage)
  • 2 bags (2–3 cubic feet each) compost or composted cow manure
  • 2-inch layer of shredded leaves or grass clippings (grass clippings should be herbicide- and fertilizer-free)

Makes enough for a depth of about 9 inches.

Raised garden bed. Photo by Oregon State University/Wikimedia Commons.
Square-foot gardening in a raised bed. Photo by Oregon State University/Wikimedia Commons.

Planning a Raised Bed Garden

To plan out the perfect garden for your space, try the Almanac Garden Planner! In minutes, you can create a garden plan right on your computer.

The Garden Planner has a “Raised Garden Bed” feature. It also has a specific square-foot gardening (SFG) feature, which involves dividing the bed into squares to make the organization of your garden a lot simpler (see photo above).

Which ever garden you select, the Garden Planner will show you the number of crops that fit in each space so you don’t waste seed or overcrowd. There’s even a companion planting tool so you plant crops that thrive together and avoid plants that inhibit each other.

Test out our Garden Planner with a free 7-day trial—plenty of time to plan your first garden! If you enjoy the Garden Planner, we hope you’ll subscribe. Otherwise, this is ample time to play around and give it a go!

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Learn More

Have you ever thought about building your own raised garden bed? Or do you have one already? Tell us about it below!

Reader Comments

Leave a Comment

garden soil recipe

Your soil recipe says "2 pails (3 cubic feet each) coconut coir". You must mean two pails worth. A pail is much smaller than 3 cubic feet.

self-watering raised garden beds

Do you have any plans for a self-watering planters?

My repurposed trampoline

I have built a raised bed garden out of our old trampoline. Using the octagon shape of the frame work. I enclosed 7 sides and the made a 5x3 walkway up the middle. I used the degraded trampoline mat as a weed barrier. I then staples coated wire fencing to the outside of the boards and zip tied it to the round tubing that used to hold the trampoline mat. My goal is to use the pipe that held the safety netting to fabricate a roof structure so that I can cover it with plastic for a hot house, if I can find the hardware I need. I wish I could attach a picture.

Trampoline Raised Bed

The Editors's picture

That is a really cool way to reuse your old trampoline! Thank you for sharing with us. We hope you have a great crop this year.

plastic containers

i have 12 4 x 3 ft 16 inches deep plastic and want to know how to prep the for drainage.

Compost

In your recipe above for bed soil, is that the finished product of top soil, compost and other organic material? And when building my raised bed, I used treated wood. Do I need to line it with plastic, then gravel and then the recipe?

Using treated wood in a raised bed

Could one use very old treated wood (perhaps 30 years old) in the construction of a raised bed and then line the interior with weed block? Or use the old wood as a frame and then line the interior with cedar planks? Thanks and I look forward to your reply.

Raised beds on gravel

My raised beds are on gravel, should i move the gravel out from underneath the raised beds or will the gravel help to reduce weeds? I am planning on using mulch to reduce weeds and help retain moisture since i'm in a dryer climate. Please advise.
Thank you!

Raised Beds on Gravel

The Editors's picture

Hi Allison,

There is no reason to remove the gravel from under your raised beds. In fact, it can actually help with drainage! We hope this helps.

Soil recipe

I don't have access to leaf/grass clippings, is there anything I can substitute? I'll need to purchase everything at the home improvement store's garden center.

Soil Recipe

The Editors's picture

Hi Kim, You can also use straw (chop it into smaller pieces first), but avoid using hay, which can seed your garden and produce weeds. 

Durable Raised Garden Bed Kits

In your alternate materials, you don't discuss composite raised bed kits. I bought Durable Green Bed Composite raised beds two years ago and they're awesome. A bit pricey, but because they last forever, I'm not worried about them breaking down or leaching into our wet soils here in the Northwest. Take a look, and include them in an update. A good solution for serious gardeners who want their raised beds to be a more permanent part of the landscape. Oh, and they're non toxic, natural materials.

Raised Garden

I live in an area of rocks and sloping ground. I've spent hundreds of dollars over the years in an attempt to build a garden, but each year the garden mix just seems to disappear and I'm interested in your 4 x4 garden, but 1) there is no flat area, 1) I can't break up the ground below because it is more rock than soil and that soil is a horrible brown clay that disappears when it's dry and is sticky and washes when it rains. Suggestions would be helpful

Dealing with slope

The Editors's picture

It would seem that one alternative is to create steppes—yes, that’s spelled correctly. Anicient civilizations did this; some still do, in Peru, for one example. You want to make flat ground by excavating level area/s, the width of which depends on the slope, your acreage overall, the gardening area you want, and other things. Depending on the slope grade, the ingredients in your land, and, of course, your physical ability (among other things…e.g., time), you could dig yourself or hire a landscaper. Then, once you have a flat area, grow in it or set a raised bed on it. (If you grow inground, do not skip the soil test and amend the soil accordingly.)

Or instead, although again, depending on the slope grade, you might build raised beds that have a deeper side wall on the down-hill side, with other side walls built to “fit” the slope’s angle. To help to retain the soil in such a bed, you could line it; layers of newspaper (or maybe cardboard), which eventually breaks down and most plant roots can penetrate, is one option. Note, because newspaper breaks down you may at some time need to replace it. Plastic and/or landscaping fabric would not be our choice because they will break down and you’ll forever be picking pieces out of the soil.

That’s all we’ve got. If there is a garden club or coop extension service in your area (check here https://www.almanac.com/content/cooperative-extension-services) one or both of those may have other ideas or recommendations for local services.

Soil

Hi there! With the soil recipe, should I mix it all together or should I put the layers down one by one? Thank you!

Soil Recipe

The Editors's picture

Yes, combine the ingredients together in the raised bed!

Soup kitchen garden

Hi! I am planning a raised soup kitchen garden - that table of ingredients will be super helpful, thank you - and am struggling to find information on garden layouts for that purpose. Can you possible point me at some resources? Google is not helpful at all and as I am unemployed I can't afford to buy books as well as volunteer my time and muscles. Thank you.

Free Kitchen Garden Layouts

The Editors's picture

Hi Tessa, Yes! We have loads of free kitchen garden layouts. They are not categorized for “soup” but this should get you started: https://www.almanac.com/content/kitchen-garden-layouts-potager

You can find hundreds more kitchen garden planners on the Almanac Garden Planner. It’s free for 7 days which is ample time to get ideas and see if you like it!
Go to: https://gardenplanner.almanac.com/

raised bed for blueberries

Hi, I'm moving my blueberries next year to different location because they are not happy where they are now. Too many trees from the neighbors next door and an easterly location. The new location will be next to my garage and closer for watering and a southern/east/west location. I want to plant them in a moderate raised bed mainly for protection from my bulldozing hubby that wants to mow down everything. Will this work. I've already started prepping the area with newspaper and dried leaves from last year covered with cardboard and a tarp. How much more will I need to add to the soil when planting. Thank you so much for your advice in advance

Pressure Treated Garden Bed

Hello! We built a 4 x 8 raised garden bed with pressure treated (copper azole) wood but after some research I have read that this is not a good choice when using it to plant veggies but I have also heard that it is not a big deal. I am a first time gardener and was wondering if anyone else has any experience with this. I would hate to have to toss this perfectly good box that we just built but I also dont want to get sick from poisoning. Thank you for the help!

Pressure Treated Lumber for Raised Garden Beds

The Editors's picture

In the end, it comes down to personal choice and comfort. CA (copper azole) treated lumber has been known to leach copper into the soil over time, but the amount is very minimal, and the amount that subsequently makes it into the plants is even more minimal. For you to get sick, you would have to eat nothing but the veggies from the raised bed for years and years. However, some folks prefer to not take the risk and either use natural wood (like cedar) or put down a thick plastic liner between the treated lumber and the soil. 

Here is more info on the subject from Iowa State University Extension: https://www.extension.iastate.edu/smallfarms/toxicity-concerns-about-raised-bed-construction-materials

asparagus

How would asparagus do in a metal raised bed (horse trough) where there is a metal floor? Would a 1' depth be enough or would 2' be smarter? There is a drainage plug at the base. I'm guessing maybe line the bottom with gravel or rock? Thanks for your help.

plant asparagus in a raised bed

The Editors's picture

Asparagus does not like to have its feet “wet,” so be sure that your garden bed has good drainage. For that reason, raised beds can be a good place to plant asparagus.

CCA myth

Chromated Copper Arsenate (CCA) lumber is still produced for primarily marine applications but was voluntarily removed by the manufacturing companies from residential applications in 2004 due to consumer concerns. Since the EPA assumed responsibility for chemical pesticides in 1970, CCA lumber has never been suggested for retirement or voiced concern about leaching. They always warned against burning due the concentrate produced. That said, I prefer eastern red cedar due to it being superior in longevity, locally available and, frankly, an invasive species following cleared forests. I also prefer the asthetic of cedar.

Sloped Ground

You do not need level ground to build a raised bed garden. I built one on a significant slope using 6x6 timbers, stacked three high on the lower end like a retaining wall. Filled it with good soil and it produces well. It's about 12 x 14, so it's one you walk on, not one you simply reach into. I plan to add onto it this spring.

Blight

I have 4 smaller raised beds 2 years ago I noticed all my tomatoes were getting black spots while small and green and would be rotted with blight by the time they were red.
Last year I moved them to a different one of the 4 and separated them to make sure air flow was achievable they not only got the black spot but so did everything else in all 4 beds. I sprayed over the counter fugicides and treatment.
Is this a common thing?
How do I get my garden back?

Blight

Stop the fungicide treatment - this is not a fungus. Take three or four calcium tablets (like Tums), crush them with the back side of a shovel (use a stone or a brick) and add this powder to a watering can. You have calcium deficiency in your soil. This should take care of your bottom black spot 90% of the time.

compound wall garden

Dear sir,

i would like to construct garden on top of the compound wall. tank Depth x width is 300x300mm.

is it enough size for gardening.?

Please clarify.

300mm x 300mm

That's only about one foot by one foot. Can't grow anything but a flower in that size plot.

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