How to Build a Raised Garden Bed

Planning, Building, and Planting a Raised Garden Bed

January 10, 2020
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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

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

Building Raised Garden

The Editors's picture

Rhett Butler? You don’t say what type of nematode or which plants they affected, but generally speaking, crop rotation is the best way to avoid harmful varieties of nematode affecting your crops in subsequent years - a five year rotation is ideal for most crops. Marigolds are also said to be beneficial in preventing nematodes, particularly when grown repeatedly over several years.

I am putting a very LG raised

I am putting a very LG raised garden on the side of my house made of cinder blocks. There are no vegetation already growing. To help not buy so much dirt I am placing a layer of rocks. Do I still need to use a weed fabric and does it need to be under the rocks or can it go over?

If you’re placing a layer of

The Editors's picture

If you’re placing a layer of rocks down this will help to suppress most weeds, and if there’s no vegetation there at the moment then it’s unlikely you’d need to use weed fabric too. If you do decide to use weed fabric it would be easier to place it straight onto the ground then put rocks on top, being careful not to tear the fabric.

Hi there, I am thinking of

Hi there, I am thinking of building a raised bed using stone in the back garden, but there are two questions that I have.

1) The garden is quite small so I am planning on building the bed directly attached to the house. Will this cause structural problems to the house or do you think it will be ok if I use some sort of rubber/plastic membrane in conjunction with the stone wall between soil and house?

2) Currently there is a stone patio where the bed would be. I am worried this may affect drainage (and in turn make the above problem 1 worse). Do you think the best solution would be to attempt to take up the patio or is a different drainage solution you might suggest? Bearing in mind the site is beside the house i am somewhat reluctant to tear up the patio!

Cheers, thanks for help:)

Hi, We're not builders but

The Editors's picture

Hi, We're not builders but here are a couple thoughts . . . On your first question: A waterproof membrane should stop dampness getting through, but please consult a specialist if you’re concerned.
On your second question: Raised beds are often built on patios but it may be a good idea to either remove some of the patio surfacing underneath the bed if that’s possible, or else leave drainage holes in the open sides of the raised bed to allow water to drain away more easily.
 

Hi, sorry if already posted

Hi, sorry if already posted but for those like myself on a limited budget then try getting hold of unwanted pallets and use the wood from those. There are loads of YouTube videos on how to dismantle and re-use the timber from a pallet. Loads of firms will give these away for free so ask about and with a little bit of construction you can make your own beds for a few quid. If I can make them anyone can, you only need a wood saw, nails, basic tools and patience :-)

p.s check out you tube and follow some raised bed making videos they are so helpful. Happy growing everyone good luck Steve.

We built a raised-bed garden

We built a raised-bed garden out of cinderblocks recently but recently received a notice from our home owner's association that cinder blocks inhibit the drainage of water from our property.

From what I've read on this Q&A, cinder blocks DO allow for water drainage. Is this accurate? We have chickenwire under the garden but no other material preventing soil or water drainage.

I'm also disabled so the cinder block is perfect! It allows me to sit as needed on the outside. Any help you can provide that will help me fight the association policy would be appreciated.

Thank you for your help!

We're not sure how using

The Editors's picture

We're not sure how using using cinder blocks for constructing a raised bed would inhibit water drainage unless they’re against the wall of a house or if they’re being used as retaining walls on a slope. If that’s the case, knocking some holes in them for drainage may help. 

Hello I am trying to go all

Hello

I am trying to go all organic and am struggling with what to line the bottom of the raised garden bed with. It is on 3 foot legs, 3.5x 7 feet.

I don't want to use poly plastic as these have chemicals. Any idea what would work? Perhaps coffee bags? Large foodservice bags? Not sure.

Thanks

Try weed-suppressing but

The Editors's picture

Try weed-suppressing but porous landscaping fabric, which will allow water to drain away. There are lots of different materials and brands available, so you may need to check what it’s made of before you buy it.

Liner

I'm curious if anyone has tried a potato sack repurposed? Maybe that would be worth a try this year. Let me know, my first time building and growing from scratch this year, I've used landscape fabric for a raised stacked garden bed. It measures 5x5' (by 12") on the bottom and is made of western red cedar. It's in a full sunlight area and on level ground. Would you recommend using old potato sacks or do they contain chemicals we aren't aware of? I'm growing organic non-gmo heirloom vegetables in there and I cannot find anything on what veggies to put beside which.

Hi , I made a raised garden

Hi , I made a raised garden bed from untreated wood. It is 3 ft by 3 ft, nailed at the corners. It is 12 inches deep. Now the wood has warped and the corners have become loose. How to keep them together now?

We're not sure what kind of

The Editors's picture

We're not sure what kind of wood you used. Some wood is not suitable for outdoor use (such as red oak). You may be able to cure the problem in the short term but it may continue to occur because of the moisture problems.
For now, perhaps try to wet the boards (or wait until after it rains) so they'll bend and clamp the boards before putting in support brackets? If you did use the wrong wood though, it will only be a matter of time and you could just deal with it now and replace with pressure-treated wood or rot-resistant wood more suitable for outdoor use.  Or, forget using boards entirely and border with bales of hay that you replace every few years.

I am planning a 4x8x12 wooden

I am planning a 4x8x12 wooden garden
When planting seeds what is the best placement of them i.e. green beans tomatoes,peas,pumpkins and melons ? Thank You

Also do I need to dig up the

Also do I need to dig up the grass sod underneath of it or can I just use mulch fabric ?

If your beds are 12” deep

The Editors's picture

If your beds are 12” deep then this should be enough to kill off the grass below, but if you have perennial weeds among the grass or very invasive grass species, you might prefer to put down mulch fabric or newspaper several sheets thick as a barrier below your bed.

If your peas and beans are

The Editors's picture

If your peas and beans are climbing varieties you might like to grow them on the North side of your bed to avoid shading your other crops. Tomatoes are also tall, while melons and pumpkins will sprawl across the ground (unless you train them up a trellis or similar). Our Garden Planner automatically spaces plants to make it easy to see how many plants you have room for. You can find out more and take out a free trial at http://gardenplanner.almanac.com

If I were to do a 12 inch

If I were to do a 12 inch raised garden over a spot that was previously a garden , should I place landscape fabric under the raised garden between the ground and raised garden? Or should I just double dig the ground and place new compost soil over it?

There’s no need to place

The Editors's picture

There’s no need to place landscape fabric underneath the raised bed, unless you have a problem with perennial weeds which might make their way into the raised bed. 12 inches of soil will be enough for most vegetables, so you don’t need to dig the ground beneath either.

I am thinking of building a

I am thinking of building a raised veg garden. Because of back issues I am thinking I would like to build one 3 ft high at lease. I am also on a limited budget. As I will only need 12" or so of soil for the vegies, what could I use to fill in the bottom 2 feet that won't cost a fortune?

Some people fill the bottom

The Editors's picture

Some people fill the bottom of taller raised beds with rubble as this is often available free or cheaply. 

What can you fill the bottom of a taller raised bed

What would be advised that would not impact the “organic” status of our garden?

Raised garden, plastic lining

Raised garden, plastic lining or not??

would it effect my ground

would it effect my ground water in any way to have a raised bed garden right near and around my well? It would be an organic garden, but wondering if this should be avoided altogether Thanks

I want to use cinder blocks

I want to use cinder blocks to make some raised beds. We have 150 of them hanging around. I understand there is ash that comes from coal in the cinder blocks, so they are not advised for food crops. Actually some articles say it will leech, some say it would take chemicals to make it leech. I keep reading you can line the beds with plastic. Can you all tell me what type of plastic you are using? Is it something special?

When lining raised beds, most

The Editors's picture

When lining raised beds, most people will use an impermeable plastic sheet that is thick enough to last a long time. If you’re unsure of its suitability for food crops, read the label or contact the manufacturer for advice.

You might consider using weed

You might consider using weed barrier cloth. It doesn't break down so much and won't allow a pool of water lying in the bottom

I am placing a raised bed on

I am placing a raised bed on an old rock garden. It has a couple inches of pea rock. Should I move all the rock out or just fill with new soil on top? Is it good for drainage or better to move the rock?
thanks

You can build the raised bed

The Editors's picture

You can build the raised bed on top of the rocks. They will provide good drainage and keep weeds at bay.

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