How to Build a Raised Garden Bed

Planning, Building, and Planting a Raised Garden Bed

December 21, 2018
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) peat moss
  • 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

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

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.

raised beds

I have been working with raised garden beds for at least ten years, in both the damp west coast climate of British Columbia and now in the two season sub-tropical southern Andes of Ecuador. I have used 'used' wood in both locations but in BC it was cedar and was perfect. I think the used planks here are mostly pine and they started rotting after one year. it is very humid and rains a lot in the, ahem rainy season. I have just re-located my veg garden and used the outer cuts of logs which are fresh, cheap, thick and really wonderful to look at. I am not into perfection so there is a bit of uneveness but my carpenter friend and i did our best and he evened up one connection of the boards. Otherwise i suppose the ideal would have been to take a better look and saw and smooth a bit before putting in place. What I know, however, is that once things are growing vigorously no one is really going to notice. and these cuts should last a long time. These cuts BTW all provide at minimum a ten inch depth and were ten feet long so that pleases me. They have been laid on top of stoney, poor soil and I just push up the stones and whatever earth there is against the bottom edges. Having already positioned the other boxes this way i know that the soil in the bottom still becomes quite rich and the stones provided excellent drainage. I cleared most of the compost into a new box, and have laid out sweet potatos on the used ground patch. This original area was covered with a couple layers of cardboard, the boxes put in place and filled - lasagna style - and then I laid out wood shavings surrounding the boxes. Anything that self seeds has found its way in between the boxes. LOL Remember this place never has winter, so I have borage, plantain ( a medicinal plant here), and arugula (rocket) popping up. It's actually quite pretty. Again, I am not into perfection so this wildness provides grazing for me and the bees and I am leaving most of this for now. I amy put in a fruit tree int his area. A blogger from the northern states said he didnt care about the unkind comments about not cleaning up between his boxes. He figures bugs need to eat something so he finds they go after most of the weeds and leave his boxes alone. I like this philosophy but my garden was much prettier!;)

Starting a raised garden at school

We are starting a raised garden bed project at our local elementary school. We are excited to use the great tips you have here! Thank you

Raised beds

I moved from Minnesota, USA to West Virginia, USA, so I went from USDA Zone 4 to USDA Zone 6. That's the good news. I'm now living in an apartment which is right up against a mountain. The mountain has a "knee" about 1-2 ft high about 6-8 ft wide; it rises up sharply after that. It's also rocky - the rocks rise right up through the soil. The soil here is heavy clay, and it rains all the time. I decided to locate the raised beds on the knees of the mountain in order to get as much drainage as possible, and having the beds raised will improve the drainage more. I can put better soil in the beds than the clay: I spent three years amending heavy clay soil in Minnesota, so I know it can be done but it's a lot of work. (I have to say that the soil here is really rich.) Naturally, with a mountain as a neighbor and practically a roommate, I have deer, raccoons, and possums. I will have to screen the gardens in order to keep the critters out. I'm also going to grow some veggies in pots on the deck in front. Luckily, it faces south, and the area behind the house gets full sun as well. I didn't move in early enough this year to start the gardens, so I'm preparing everything for next year. I was able to start the compost heap, but the weeds are high and we have copperhead snakes too (which lurk in the weeds). I'm pulling the weeds out to make a safe path to get to the compost, and putting the weeds in when I get there. I found a neighbor who has some old hay bales and he said I could have them for mulch.

My raised garden in Sydney NS

Constructed as a birthday gift for my wife, I built the raised vegetable bed 15L'x5'W and 14" deep from old deck placed down side up on 4"x4" deck legs. Extra 8x1 sides added to give it the 14" depth. 3/4" electric pipes were use to create arches above the bed were 40% sun blocking canopy net was placed (mostly against the almost constant wind gales) . The irrigation system is built with rain barrel as water source feed into wetness controlled ceramic cone pegs. The ceramic cone pegs have the ability to sense the wetness level underground and automatically draw what ever level of water the roots need by triggering the water valve control in the rain barrel. The rain barrel placed at 100 cm height above the raised bed to provide the require one atmospheric pressure the irrigation system requires.

Cat toilet

My cat used my raised garden bed for a cat toilet and some neighbor cats, also. Do I replace the soil I put in last spring? I have turned the soil in the bed.

cat toilet

You don't need to replace the soil, but wash your hands thoroughly after gardening and wash your produce well too. If pregnant, be especially careful due to risk of toxoplasmosis.

I lay sticks in a criss cross pattern over bare soil to discourage cats from enjoying my nice loose garden soil for a toilet. Luckily my cat thinks it is uncivilized to go in the outdoors, but there are some ferals in the area.

Cat Toilet

I had that same problem with neighbor cats. I scooped out the poop and I scooped very deeply. I would never dig cat poop in! How disgusting is that! Plus it acts like an attractant. I inserted sticks everywhere. Small sticks, large sticks, and everything in between. I inserted them about 6 to 12 inches apart. It seemed to train them not to use my garden as it was no longer easily accessible. I pushed them in about 2 inches and about 4-6 inches apart. It made it difficult for the little buggers to get in and do their thing. I also covered my garden with pieces of card board and news paper during the off season. It trained them to move on or get lost. Any way they stay away from my garden

Raised Beds on Legs

This year I had to remove my raised beds to make room for a goat barn. I've decided to build new beds on legs, approx. 12" off the ground. My previous beds would fill with wire grass (Bermuda?) so bad every year it was impossible to keep them out. Landscape fabric didn't do a thing to block it. So now I'm building off the ground to avoid that issue. What I'm wondering is how high do the bed sides need to be since they're completely off the ground and won't have the benefit of the ground soil below? Will 12" of soil be enough? I had thought I'd use hardware cloth and landscape fabric in the bottoms with 2x4 supports every few feet to hold the soil's weight. I plan to build each one 4 ft x 8 ft x whatever height I need for soil. Any suggestions on height?

Raised Bed Height

Making them 2 to 3 feet deep would be ideal. To grow the healthiest plants, 2 feet is great, but if that’s too deep for you, 18 inches is fine. 

Raised beds

You should make sure the bottom of your raised bed on legs has a secure bottom I bought one I did the proper layering then watered.I came out next morning and the bottom fell out I rescued a few plants and promptly turned it upside down and use it as a raised bed on the ground I am short so it was better for me.You can buy brackets that secure the bottom if need fixing.

plastic sides in place of boards

Is it OK to use plastic boards for the sides? I'm thinking of the type of recycled plastic that is often used for benches or boardwalks these days. They seem very sturdy and of course won't rot. But do they leach chemicals? I see them often use das boardwalks in sensitive-drainage areas e.g. wetlands.

RAISED BEDS

I've been using "plastic lumber" for raised beds for over 10 years with no problems, just use plastic stakes for the longest run and you'll be fine.

Bindweed

Been killing about a 10' x 10' patch of bindweed in part of my garden plot. I have dug, tilled, pulled, and finally sprayed with Hi-Yield 2,4-D Amine a selective weed killer". It's still growing and coming back. I'd like to make a raised strawberry patch in this area. How oh how can I rid myself of this horrible weed whose roots can go to 40' depths I'm told! And how do I put my berries above this pest and not have the weed come up and in to the patch? Thank you for help and advice!

nasty bindweed

I would not use chemical herbicideds in my veg garden, but maybe you are growing ornamentals... Have you tried smothering the soil? The problem with tilling is that you probably have hundreds and hundreds if not thousands of seeds in your "seed bank", and each time you disturb the soil, you have more seeds germinating, not to mention the roots that keep regenerating plants. I would seriously consider covering the area with newspaper and then cardboard, and putting a good 12 inch layer of clean compost and soil on top of that. Plant what you want and be vigilant about weeding. Good luck!

Raise beds but higher

I have some problems with getting around so i thought i would build some raised beds but they set off the ground about 3 feet, that is the bottom of the bed. ? is what would be the best way to do the bottom of the bed. I thought to make a inner 2x4 and attach (?) to that. Wonder if i should go with a brace wood plank system and then but in metal mesh, and some stone for drainage. Any help or suggests please send to me address emails as garden helper at subject. Believe me i have went thru this a 100 times Please i need HELP, Thank's to you all ahead of time, GOD BLESS and happy Gardening

raised garden bed and cement ruble

Hi
I am new to gardening.We had some spare materials so we are making a raised garden bed out of sheet iron/old color bond roofing. Now we are in the process of filling it.We put cement chunks on the bottom at a height of around 8inches.The sides of the bed are 20inches in height.
My question is what do we fill the gaps with around the cement pieces with?gravel? sand?or just keep filling to the top with good organic soil?
And when the bottom 8inches is filled do I ad paper or something? or just top it up with organic soil?
Thanks in advance.

raised bed materials

The Editors's picture

We are not familiar with color bond roofing; a search suggests its an Australian product, so g’day! It may work as your wall but being metal it may also heat up more than natural materials (wood, say) and so conduct heat to the soil adjacent to it. Not necessarily a bad thing; it might depend on how hot it gets…and because of heat dries out the soil. Why 8 inches of concrete? What is underneath the concrete, soil? A hard surface? Is the 8 inches of concrete instead of soil, so you can save on soil? As for filling around the concrete, do some homework on what you want to grow. Some plants need a good 12 inches of soil, minimum, but some experts recommend up to two feet of soil so plants can spread their roots. You don’t want roots up against the concrete.  The soil will pack in around the concrete; so would sand, but sand does not benefit the roots; it helps—or increases—drainage, and you don’t want water to pour out. You could spread a little newspaper over the concrete but it will not last long; it may be better to fill with good organic soil and save the paper (newspaper) for possible use as mulch. To a certain extent, this will be an experimental season for you. Let us know how it goes!

 

Waist high raised bed but with only a 12 inch depth

We are changing over from a straw bale garden to a wood raised garden. Has anyone seen any free designs for a raised bed that is about 3 foot high but only want the depth of the bed to be about 12-15 inches? My husband is concerned about the best method to stabilize the bed since it will not be supported "by the ground", but elevated. Any ideas? Thank you.

Old tires for raised bed garden

Has anyone tried stabilizing old large tires for a raised garden bed? Is the rubber safe for use when growing food? I want to build a raised bed that will save some wear&tear on my lower back. I also prefer finding new uses for products to help reduce our ever growing landfills. This would also be economical for me. Thank you.

Old Tire Raised Bed

Hi Cynthia,

In the short term, yes you can make a planter out of old tires. However, over time the tires will degrade and release toxic carcinogens into the soil. If you want to use the planter for more than a year, it’d be a better use of your time to use a material other than tires. 

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