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!

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Reader Comments

Leave a Comment

nematode nemesis!

The Editors's picture

Thanks for taking the time to share this great advice, Rononpi! You have clearly found a success method for defeating the problem of nematodes, and it’s highly likely that other gardeners will find this information helpful. We certainly did! All the best—

FL follow-up.

I am in South Florida as well. How deep are your beds... and What do you recommend putting below the soil to help with water retention?

Mixing bed soil with existing soil

Thank you for this informative page! We've had a garden in the ground the last three years and weeds& pests (rabbits, slugs, deer) have always been a problem. This year we're interested in trying raised beds to deal with both. I read here you recommend mixing clay- rich ground soil with the soil/mix put into the beds, but that will just perpetuate the weed problem I think. Any tips? We plan to put chicken wire on the bottom of the frames to keep out burrowing rabbits (happens with our regular garden fence) and the cardboard on top sounds like a good idea for weed suppression. But those two things are at odds with mixing soils too. Finally, any tips for pest fencing around the beds themselves that are easy to work with? Thank you!

beds...

The Editors's picture

Above we recommend

  • Fill the beds with a mix of topsoil, compost, and other organic material, such as manure, to give your plants a nutrient-rich environment.

Clay may be mentioned below re particular issues.

As for protecting your bed, it is entirely possible you may have to fence it in. Being raised does not eliminate pest problems; for materials, it’s your call re aesthetics and practicality, from chicken wire to cottage picket.

Or weeds. Weed and other seeds can blow in, birds drop them (or excrete them)—they can come from anywhere. To (almost) eliminate weeds, mulch.

Garden Too Shallow

Hello,

Thank you for your informative article.

I bought some seedlings and I have planted them. However, I suspect my garden is too shallow.

How can I make it deeper without affecting the seedlings?

Thanks

Deepening Your Raised Beds

The Editors's picture

Use a spade fork to very gently loosen the soil beneath your seedlings. You can temporarily remove them from the raised bed while you amend the soil depth. Lift the plants (keeping the roots in soil) and store them in trays, tubs, or buckets for the hour or so it takes you to work the bed. Replant as soon as possible and water well. Be sure not to bury the stems too deep when replanting. Keep the disruption of stems and roots to a minimum.

Raised Bed

I am building a raised vegetable bed on concrete. Is it best to line the bottom and sides with a liner. Or leave out the liner and add gravel on the concrete. Or use a liner then some gravel on top of liner to help drainage. Look forward to hearing from you with any advice.

Concrete raised bed lining

The Editors's picture

Hi Lesley,

A good way to go would be to use gravel on the bottom, then line it with landscape cloth.

lining with landscape cloth

Why add the landscape cloth? Is it necessary?

Landscape fabric

The Editors's picture

Landscape fabric is not required. Some gardeners use the cloth as an easy way to suppress weeds.  Fabric allows for the movement of air and water, unlike plastic. However, other gardeners do not like to use landscape fabric because it requires heavy mulching to cover the fabric and it breaks down over time.

Another solution is simply to layer 4 ot 6 inches of organic mulch such a bark or wood chips. This layer of mulch will prevent weeds by blocking light from getting to the soil. It also helps retain soil moisture.

Hi, I am purchasing a 1/2

Hi, I am purchasing a 1/2 acre that I want to put up a 8 ×12 greenhouse along with an 20 × 40 garden. I need help and suggestions for this project. Thank you for your help. Bev

Treated wood for raised beds

I have new raised beds brushed with Thompsons water seal.I'm trying to find out if this wood is now safe for using it for vegetables boxes.

We’ve never used this product

The Editors's picture

We’ve never used this product as don’t seal our wood; I’d call Thompsons.  That said, if it’s already brushed on, it should certainly extend the life of your wood. Just in case there is any leaching of its chemicals, perhaps avoid planting root crops right up next to it in the first year. Again, it’s best to call the manufacturer.

Raised beds

I am building raised beds, now I have been told to put down black plastic and build the beds over that to keep weeds down and help retain moisture, but with that said, has anyone done it that way? I have also been told if I do that, to poke holes in the plastic to help it drain? Recommendations?

bed cover

The Editors's picture

Here’s a link to a recent video we made explaining the ground cover:

https://drive.google.com/file/d/0ByNeFIPHh8-lWlJMaVpKSWpZS1U/view?usp=shari
ng

If you use plastic, you should poke holes in it, otherwise you will have water collecting, eventually drowining your plants. Remember, the holes will invite weeds in…

The video uses a weed cover. This has inherent problems because some weeds will grow through it eventually.

Another alternative to both plastic and weed cover is sheet cardboard (boxes broken down and flattened). Or several layers of newspaper. Both of those impede weeds and and slow water run off/dissipation into the soil, and they eventually break down.

That’s all about retaining moisture and suppressing weeds under the garden.

On top, use mulch to retain moisture and suppress weeds.

Raw untreated pine beds

Hi the post by Unlearn got me thinking

I am very interested to know more about using raw untreated pine. Planning vegetable beds for my garden, and don't want to use anything treated / plastic that could leach chemicals

Also want something that will be really durable, don't want to have to rebuild in 5 years time. I read somewhere that raw pine will last a long time as its full of resin. Any experience of this? Any practical issues with using raw undried wood? (Will it shrink once in place?)

I'm no expert but I read somewhere that a waterproof lining can be counterproductive, as it traps moisture next to the wood

untreated pine for garden beds

The Editors's picture

Untreated pine isn’t particularly long-lasting. Five years is often suggested as a maximum before it begins to degrade. Cedar or larch is a much longer lasting material. Any wood does contract over time as it dries out, so you may find it easier to use wood that has been dried first.

Pine Raised Beds

I think exactly as you do. Not sure about the resin, but while researching possibilities to protect the wood, I found raw linseed oil is non toxic and made of flaxseed oil. It takes longer to dry (48 hrs) than boiled linseed oil but worth the wait.

Raised garden bed patio vegetable planter

My un-treated cedar frame arrived today. There is no base to it; its a frame. If I put it on the patio of my townhouse (which is not 100% level) what do I line the base with? I am unsure if landscape fabric can be used for this purpose?

raised garden bed planter

The Editors's picture

You can use landscape fabric if you want to line the base, though a raised bed can be placed straight onto a patio without a liner.

raised herb garden

I have a space about 3x12 between a screened porch and patio that i'd like to turn into a raised herb garden.. with maybe some string beans going up the back... never done this before, but its in a total sunny location (although low and gets a lot of rain - which is why I'm doing the raised option).. do you think this is a good idea?

It’s a great idea. Just make

The Editors's picture

It’s a great idea. Just make sure that the bed drains well and doesn’t collect too much of the rain water.

Great page! Glad I found it.

Great page! Glad I found it.
Thanks to a rather large wind storm & some hard work I have a nice supply of rough cut pine. The pine is being used to make raised veggie beds & I want them to last as long as possible. I'm thinking about lining the inside (sides only) of my new beds to prevent the direct contact between earth & raw pine. Trying to keep bugs & rot from bringing an early death to my beds.
My concern is lining these beds with something that will protect the bed sides & at the same time not have any adverse affects on the food I will be growing in them.
Is there a material designed for this purpose?
Is one type of poly good & others bad? (lots of conflicting info out there)
What about rubber, an old pond liner or like?

Someone on a forum somewhere suggested using "house wrap". A product named "Tyvec" is common here. New build homes are wrapped with a waterproof membrane (this Tyvec) between the plywood sheeting attached to the framing & the outer finish surface (siding/brick) of the home.
This actually appeals to me, as small scrap cutoffs are always available at new construction sites.

The bottom line is, I NEED the food to have no chance of contamination & I WANT to get the longest life out of the boxes I'm building. Can both be accomplished & with what?

Any info you can share would be much appreciated.

Thank you very much
UnLearn

treated waist high planters

What can I do to keep the chemicals from leeching into my herbs,and, vegetables with. I'm growing organically. Can I line the big boxes, or paint the interior with BP free paint. What kind of liner would work? I don't want to poison us for the sake of our backs.

Raised Beds Lining

The Editors's picture

Hi Debbie, You don’t say what your boxes are made of, but for maximum peace of mind I’d say impermeable plastic would be better than landscape fabric, which is usually porous to prevent waterlogging when used on the ground. Alternatively, using boxes made of a long-lasting, naturally rot-resistant wood such as cedar or larch is a good choice as it doesn’t need to be treated.

How to keep groundhogs out of my garden?

I really want to do the raised beds for my garden this year. My soil is very poor so this should help. Last year I worked very hard with my garden and it was coming along splendidly,and then one day I go the my garden and there isn't a plant to be seen and there is a groundhog eating the remaining watermelon sprouts! How do I keep them out!!??. I don't want to hurt it, just discourage it.
Thank you!
Sincerely,
Mary-Elizabeth

Keeping Groundhogs Out of Garden

The Editors's picture

We have an entire page with advice on how to keep out the groundhogs! See here: 

http://www.almanac.com/content/woodchucks

Walnut tree in our yard

I gave up our garden several years ago because of A walnut tree now I'm thinking about raised garden It will be about 50-60 feet from the tree trunk I think I'll need a bottom to keep tree root out I have several pieces of steel roofing I'd like to use and 2x10 sides that would make it 32" wide by 8 feet ,2 of them ,any suggestions

Raised Bed Gardening

The Editors's picture

Hi Rich, You should be fine building raised beds with thick landscape fabric beneath to help stop roots getting in, so long as the canopy of the tree doesn’t extend over the bed (nuts and leaves also contain juglone, the substance which is toxic to some plants). Here are a couple of links that explain further:

http://lancaster.unl.edu/hort/articles/2003/juglone.shtml

https://hort.uwex.edu/articles/black-walnut-toxicity/

Nematodes

Want to build raised garden in areas where nematodes have been a problem. Should I use some sort of liner in the bottom or any suggestions to get rid of nematode

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