How to construct a raised planting bed

How to construct a raised planting bed

In addition to providing an aesthetically pleasing element to your garden, raised beds create favorable conditions for plants. If you have poor soil conditions in your yard, using a raised bed lifts the roots of plants above undesirable soil and gives them room to grow in a better medium with good drainage.

Lumber

The best type of lumber for raised beds is unpainted and untreated planks of hardwood. Ideal wood includes oak or locust. Do not use pressure-treated wood or lumber that contain chemicals that might be toxic to plants. This includes creosote, copper sulfate or penta chlorphenol compounds.

Power Tools

When you start building your raised bed, you’ll need a large diameter circular saw and a drill with a ½-inch spade bit. If you don’t own a circular saw, rent one from a hardware rental center. It is helpful for making clean, accurate cuts in the wood you use as frames for the bed. You can also use a handsaw to cut lumber. The drill is for drilling holes in the lumber and securing the lumber with timber screws to make the walls of the raised bed.

Hand Tools

A shovel and hoe will clear the ground and create a trench for the lumber used in the raised bed. They also come handy for creating a vertical outline around the lumber pieces when you place them on the ground in the arrangement you desire for the raised box. A level lets you make sure that the lumber is even from corner to corner. A speed square helps to make sure that the edges of the lumber are cut at precise angles. A sledgehammer will drive rebar through the holes in the lumber to secure the wood to the ground. To create drainage in the bed, you can drill holes through the sides of the timber, then use short lengths of small copper pipes to insert into the holes to protect the lumber and make it easy to clean clogs.

Gravel and Soil

Gravel is for filling the first few inches of the trenches for the lumber. A trench for a simple rectangular raised bed should be 6inches deep, with the first 2 inches filled with gravel. Gravel is also for the main area of the bed once you finish constructing the frame. After filling the bed with 3 inches of gravel, use the hoe to smooth it out. Approximately 6 inches of topsoil goes on top of the gravel. Use a rake to smooth it out before planting. For most plants, a sandy clay loam mixed with peat moss or other organic matter like composted manure or ground bark provides a well-drained soil mixture. You can also buy premixed soil to add to the bed.

Other Supplies

Construction adhesive helps to keep layers of lumber in place while you are drilling and sawing. If you don’t want to use lumber for your raised bed, you could use bricks or stone for the walls. You will need to add concrete to bricks and mortar to stones to secure them. Follow safety precautions when cutting wood, and wear goggles and gloves.

This article was co-authored by Steve Masley. Steve Masley has been designing and maintaining organic vegetable gardens in the San Francisco Bay Area for over 30 years. He is an Organic Gardening Consultant and Founder of Grow-It-Organically, a website that teaches clients and students the ins and outs of organic vegetable gardening. In 2007 and 2008, Steve taught the Local Sustainable Agriculture Field Practicum at Stanford University.

There are 13 references cited in this article, which can be found at the bottom of the page.

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A raised planting bed is a large planting box or enclosed garden bed that’s elevated slightly above ground level. These beds are ideal if you have poor soil quality or bad drainage in your yard, since they give you a little more control over your plants’ growing environment. An elevated bed can also help save your back and knees by reducing how much you have to bend and kneel! [1] X Research source To build a simple raised bed, first find a flat, sunny location in your yard. Construct a frame for your bed with durable wood planks and fill it up with vegetables or flowers.

So last summer’s homegrown tomato crop was more of a bummer than a bumper, and after a few exploratory backyard digs it seems less likely that you’re going to hit pay dirt. But that doesn’t mean going hungry. By building a raised planting bed, you can set up your seedlings with a loamy home as fecund as the Fertile Crescent.

Surrounded by timbers and filled with rich soil, the raised bed lets you customize your plants’ nutrients and moisture. It also brings the garden to the gardener, allowing you to easily maintain your plants without stooping.

And if you build it early you can get a head start on the planting season because the elevated soil heats up sooner than the ground. Then not only will the handsome structure help define your garden but never again will bad dirt stand between you and a good BLT. Learn how to build a raised flower bed in the steps below.

Step 1

Raised Planting Bed Overview

Illustration by Gregory Nemec

A raised bed is nothing more than a giant planter, a box of topsoil with timbers for sides. You can build it in any sunny, level spot, or you can excavate a slightly sloping location to create a level surface (though this adds to the digging). The box itself can be made from any size lumber—the larger the pieces, the fewer you’ll need. Cedar or redwood timbers look nice and are naturally weather-resistant. Pressure-treated wood is a less expensive, albeit less polished, alternative, and preliminary EPA tests have shown today’s treated lumber to be a safe material for use in vegetable and herb beds.

Before you build your bed, you’ll need to figure out how big you want it to be. “The beauty of a raised bed is its accessibility,” says This Old House landscape contractor Roger Cook. “It should rise at least a foot off the ground—this gives the plant roots room to grow and gives the gardener’s back a break.” Stick with 4 feet or less for the width, says Roger, so you can reach the middle of the plantings from either side; when it comes to length, the limit depends on the size of your lumber. If you use the same beefy 6×6 timbers shown here, you shouldn’t go beyond 10 feet because the timbers will get too heavy. To cover a larger area, build side-by-side beds with room to walk between them. Because the bed’s first timbers are partially buried, you’ll need to guard against rot by laying 2 inches of gravel beneath them. This promotes drainage and also provides a solid footing. For the bed itself, line the bottom with more gravel and drill weep holes through the timbers’ sides.

Most of the precision and muscle work in building the bed comes in digging the trenches and leveling and squaring up the first course of timbers. Once the first course is laid properly and spiked to the earth with rebar, assembling the rest of the bed is a matter of piecing the sides together like building blocks. The whole thing fastens together with timber screws. Then you simply add a railing, shovel in the topsoil, and plant your new garden.

Step 2

Mark the bed’s outline

Photo by Kolin Smith

The timbers that make up the walls of the bed will butt against one another end-to-side at the corners. So to determine how long to make the timbers, subtract 5 ½ inches (the true width of a 6×6) from the length of each side. Using a circular saw and handsaw, cut 12 timbers to length.

Clear the site of obstructions and arrange 4 timbers in an outline of the planned bed, butting each timber’s end against the next timber’s side. Using a spade or square-edged shovel, mark the bed’s outline by cutting vertically through the turf both inside and outside the loose-laid timbers’ perimeter.

Step 3

Dig trenches for the walls

Photo by Kolin Smith

Set aside the timbers. Using a spade, remove all the turf within the outer lines. Switch to a trenching shovel and dig a 6-inch-deep trench in the outline of the timbers.

Fill the trench with 2 inches of gravel. Use a hoe to spread the gravel level.

Tip: Roll up the turf you remove and reuse it to patch your lawn. Place the soil you dig out onto a tarp and use it inside the finished bed.

Step 4

Set the first course of timbers

Photo by Kolin Smith

Using a drill/driver fitted with a ½-inch extended spade bit, drill holes through the four base timbers every 2 feet.

Lay the timbers in the trenches with all the pilot holes vertical. Arrange them so the butt end of one meets the side of the next in a clockwise fashion.

Using a 4-foot level and framing square, level and square the four timbers, adding or removing gravel as necessary.

Place the level atop a scrap of lumber laid diagonally across the timbers to check for level corner to corner.

Step 5

Fasten the frame with rebar

Photo by Kolin Smith

Using a sledgehammer, drive a length of rebar through the pilot holes in the timbers and at least 1 foot into the ground. Check the frame for level and square as you proceed.

Hammer each rebar flush with the top surface of the four timbers, being careful not to hit the frame so hard that you knock it out of level.

Tip: To cut rebar to length, saw halfway through with a hacksaw, then bend to break.

Step 6

Assemble the bed’s walls

Photo by Kolin Smith

Lay the next course of timbers on top of the base course, but arrange them counterclockwise so they overlap at the corners in the opposite direction from the first course. This will create a lapped pattern.

Using a drill/driver, drive timber screws down through the top course and into the timber beneath, two at each corner and one in the center of each side.

Step 7

Drill weep holes

Photo by Kolin Smith

Using an extended ½-inch spade bit, drill weep holes for drainage through the second course every 4 feet. Drill from the outside in, to keep the holes looking neat, and angle the bit upward so water will flow out.

Lay the third course of timbers clockwise on top of the second, lapping the corners again. Fasten them to the second course with timber screws in the same manner.

Tip: Slip a short length of ⅜-inch copper pipe into the weep holes to protect the wood and make clearing clogs easier.

Step 8

Install the cap railing

Photo by Kolin Smith

Lay a 2×8 board on top of one wall. Line it up flush with the inside edge. Mark the board where it meets the inner corners. Using a speed square, extend this mark at a 45-degree angle projecting outward.

Using a circular saw guided by the square, cut the ends at 45-degree miters. Repeat this process on the other three sides of the bed until you have a frame of 2x8s that sits flush with the inner edge of the bed and protrudes 2 inches over the outer edge.

Apply construction adhesive along the top of the timbers and on the board’s mitered edges. Lay the boards in place. Fasten them to the timbers with 3-inch decking screws every 12 to 16 inches. Drill a horizontal pilot hole through the rails edge and across the mitered corner. Drive a 3-inch screw into the joint to prevent it from opening.

Step 9

Fill the bed

Photo by Kolin Smith

Shovel a 3-inch layer of gravel across the bottom of the bed and smooth it with the hoe.

Fill the bed with topsoil, tamping it lightly every 6 inches to reduce settling later.

Fill to within 2 to 3 inches of the top of the bed. Rake the soil smooth and plant.

How to construct a raised planting bed

Home food production is a growing trend in Florida gardening once again. There’s a new wave of gardeners who are hoping to grow their own food and live a more sustainable lifestyle.

Gardening in raised beds can help improve yields and reduce maintenance in your home vegetable garden. Here we will walk you through the steps to build raised beds. For more on caring for your beds and plants, see our article Raised Beds: Benefits and Maintenance.

Materials and Construction

While raised beds do not technically need a framework, we do recommend one for long-term gardening. Frames can be constructed using a variety of materials, including brick, rot-resistant lumber, landscape timbers, and concrete blocks. Beds can also be elevated for gardeners who want to avoid working at ground level.

Generally, wood-based products are less expensive than stone or masonry materials. Sometimes it is possible to get building materials secondhand at little or no cost. While recycled lumber is not a good choice for edible gardening, used bricks, concrete blocks, and other recycled materials are an option. To tie your landscape elements together, match your raised-bed materials to other materials used in your landscape.

Here are some popular materials used to construct raised beds:

Wood / Lumber

  • Untreated lumber – begins rotting within a year, but it is safe for edibles
  • Naturally rot-resistant lumber – examples include redwood or cedar
  • “ACQ Ground Contact” treated lumber – approved by the Food and Drug Administration for food production
  • Synthetic lumber – made of recycled plastic

Other Materials

  • Brick or stone – long-lasting but often expensive
  • Large, grouped containers – examples include half-barrels and large terracotta pots
  • Concrete blocks – may result in an alkaline soil pH but the effect will decline over time
  • Poured concrete – check that curing compounds, stains, sealers, and release agents are safe for use in edible gardening; as with concrete block, an alkaline soil pH may result

Cautions for Vegetable Gardeners

How to construct a raised planting bed

Whether you are a new or an experienced vegetable gardener, a cautious approach to edibles is wise. Products and building materials you might use for ornamental plants are not always suitable for edibles.

Many of the pesticides you would normally use in your ornamental beds are not safe for edible crops. Always read the label; it’s the law. When in doubt, contact your county extension office for assistance.

Avoid the use of secondhand lumber, such as that from pallets. Some lumber is treated with creosote or pentachlorophenol. These chemicals can leach out and injure plants.

Avoid recycled landscape timbers and railroad ties. Prior to 2004, these may have been treated with compounds that contain arsenic. New lumber is no longer treated with those compounds.

If you’re uncertain about the safety of treated lumber, place a heavy plastic liner between it and the soil used for growing plants. This will prevent direct contact of plant roots with the treated lumber. Be careful not to tear the plastic when tilling.

Construction Tips for Raised Beds

Raised beds can be as simple or as elaborate as you’d like them to be. Here are some general steps for constructing the frameworks.

Step 1: Choose a spot in your landscape that receives 6-8 hours of direct sunlight a day. The most convenient sites are flat and located near a source of water. If the area is part of an existing lawn, remove the top layer of grass or cover the turf with recycled cardboard, or black and white newspaper.

Step 2: Measure your site and determine the size and placement of your raised beds. Here are some guidelines:

  • Width – Beds should be no wider than 4 feet. In larger beds the center can be difficult to reach.
  • Length – Eight feet is a common length, but there is no one-size-fits-all for raised beds. The length should match your site and budget.
  • Depth – The depth of the bed should be between 6 and 24 inches deep. Deeper beds are more expensive because they require more materials. Shallower beds cost less, but may be more difficult to access. If you want the surface of the bed to be higher than 24 inches, consider elevating the entire bed above ground level. Add a sturdy bottom, with drainage holes.
  • Spacing – Leave a walkway of 18 inches or more between the beds for weeding and harvesting. Wider walkways will make the beds more accessible. For wheelbarrow access, we recommend leaving 3 feet between beds.
  • Orientation – A north-south orientation is best for low-growing crops. This allows direct sunlight to reach both sides of the bed. Beds that will contain taller crops do best with an east-west orientation. This is appropriate for plants such as pole beans and caged tomatoes.

Step 3: Once you know how big the beds will be, list the materials you’ll need and purchase accordingly. A materials list and detailed instructions for building a 4′ x 8′ x 21¾” wooden framework can be found in the publication Gardening in Raised Beds.

Step 4: Construct your beds and place them in the landscape. Measure the space between them and check that they are accessible before you continue. If weeds have been a problem on the site, line the bottom of the beds with 4-5 layers of newspaper or cardboard to create a weed barrier.

Step 5: Fill the beds with high-quality garden soil or with soilless media. Using new media rather than soil from your landscape will help the plants thrive. You’ll also get a fresh start in the battle against weeds. This is also a good time to till in organic soil amendments, such as compost or manure.

Step 6: Add your edibles! Most garden vegetables will grow well in raised beds. Still, seasons matter. Cool-season crops require cool weather, even in raised beds. Plant the vegetables appropriate for the current growing season. You will find the Florida Vegetable Gardening Guide helpful in choosing vegetable varieties for our state. This guide also includes planting dates for your region and other valuable information on vegetable gardening. For more on caring for your beds and plants, read Raised Beds: Benefits and Maintenance.

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Updated: March 31, 2020

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Use one of these free raised planter box plans to get all the advantages of a traditional garden with a lot less work. You’ll spend less time pulling weeds and more time using rich soil to grow your raised bed garden. Whether you fill them with vegetables, flowers, or herbs, you’ll enjoy the convenience of having a designated area to grow them.

Raised planter beds are a step up from a container garden, giving you more room for everything you want to grow. Consider these tips for growing a successful raised garden before you get started planning your own.

How to Build a Planter Box

This raised planter box takes it to the next level with a box that is counter-height which makes it easier to take care of your little garden. It has a nice rustic look plus a lower shelf that you can use for storage or decorations. It would look great on a deck, porch, or patio.

Raised Planter Boxes With Sub-Irrigation

How to construct a raised planting bed

This raised planter box plan gives you not only the advantage of a raised garden but also the luxury of a self-watering system. There are instructions for how to build a raised bed built out of cedar and how to add a sub-irrigation system so you only have to remember to water a few times a month.

Raised Vegetable Garden with Compost Bins

How to construct a raised planting bed

This raised planter box plan will give you everything you need to have a successful raised vegetable garden. There are three areas for plants along with separate areas for composting. The compost feeds the surrounding plants, giving them the nutrients they need to grow. There is also room for hanging plants at the top of the structure.

Raised Garden Bed

How to construct a raised planting bed

This raised garden bed plan uses inexpensive furring strips to create a 50.5" x 50.5" square bed that you can use to plant seeds or seedlings. It's an inexpensive DIY project that will only take you an hour or so to complete.

Rolling Planter Box

How to construct a raised planting bed

This raised planter box adds yet another advantage to having a raised bed garden, it's on wheels. This makes it easy to move for watering and gives you a way to protect the plants in it when the weather gets cold.

Raised Garden Planter Box

How to construct a raised planting bed

Here’s another DIY raised planter box plan that adds some added height, putting it at about desk level. A stain is applied at the end, which really elevates this project, making it look good enough to sit right by your front door if you’d like. When you don’t have anything planted in it, you could even use it as a potting bench since it’s raised so high.

Metal Raised Garden Bed

How to construct a raised planting bed

Instead of using all wood, this free raised planter box uses corrugated metal for the sides. It’s also raised slightly higher than your average raised bed, making it easy to bend over and plant seeds as well as harvest. There are also a lot of tips included on how to set up an irrigation system.

Stand Up Planter Box

How to construct a raised planting bed

This plan builds a fairly large planter box, coming in at 60" x 36". It's also raised 32", to make bending over your garden easier. Along with the free plan is a video that shows you all the details on how to build one for yourself.

Raised Bed Flower Garden

How to construct a raised planting bed

Show off your raised planter boxes with this free plan that shows you how to build them right in the front of your home. It would be the perfect place for a flower garden or even some vegetables or herbs. It's an affordable project that will add a ton of curb appeal. Your neighbors just might copy the look!

How to construct a raised planting bed

Raised garden beds are freestanding beds constructed above the natural terrain. Texas gardeners are discovering that raised bed gardens can help solve many problems. In many areas of the state the soil contains too much sand or clay, or is too alkaline for some plants to grow well. Soil that is poorly aerated because of compaction or poor drainage also may be a problem. Soil quality problems are often aggravated in urban and suburban settings, where topsoil and vegetation have been removed or the grade changed during construction.

Raised bed gardens improve growing conditions for plants by lifting their roots above poor soil. Soil in the beds can be amended to provide a better growing medium for plants, even plants that would not naturally thrive there. The soil in raised beds warms up earlier in the spring and is less apt to be invaded by certain grasses and by tree roots. Also, the height of raised beds may make them easier to maintain.

This publication details each step involved in planning, constructing, planting and maintaining a raised bed. Illustrations depict irrigation systems and construction techniques.

How to construct a raised planting bed

Raised beds can be purely practical or they be architectural features in a garden. In this article I cover how to construct raised beds for maximum vegetable growing productivity

Size of Raised Deep Bed and Paths

Width of Raised Beds

The main point of raised beds is that you never tread on them and compact the soil so it is important that you can easily reach into the centre from the side of the bed. The best width will be around 1.2M (4 feet) to allow that.

Much wider and you will not be able to easily reach the centre of the bed. Much narrower and the proportion of land given over to paths instead of growing increases, reducing overall productivity of the plot.

Length of Raised Beds

If the bed is too long, then getting to the other side will involve a long walk and you will be tempted to step over the bed so about 3M (10 feet) long is considered maximum length.

Depth of Raised Beds

A raised bed can be quite shallow but I would suggest 15cm (6″) as a minimum and 20cm (8″) as better. My own are 30cm (12″) deep and built so as to be able to add another 15cm (6″) board in the future as more and more compost is added.

I have seen raised beds that were 90cm (3′) high – ideal for those who find bending difficult or those in wheelchairs.

Paths Between Raised Beds

The main paths will need to be between 60cm (2 feet) and 75cm (2’6″) to allow easy access with a wheel barrow with the secondary paths at least 45cm (18″) wide to allow walking and kneeling as you lean over the bed.

Constructing the Raised Bed

First plan out where the beds are going and use some line to mark out. Don’t be tempted to squeeze the paths, you will regret it. Better to have a narrow bed because you will not be able to get to the bed with too narrow a path.

Deep raised beds with primary and secondary paths

Having marked out and checked you are happy with the layout you can produce a cutting list for the wood for the sides. One good source can be second hand scaffolding planks if they are in reasonable condition. Do not use wood that is too thin, like floorboards, because it will rot and be too flimsy.

225mm x 38mm (8.8″ x 1.5″ approx) boards are near perfect. Fix to stout internal corner posts, fence posts can be ideal, with non-rusting screws. Because the wood is in touch with the ground it will be prone to rot so paint with a preservative like Cuprinol, soak the corner posts, for a long life. The corner posts can be sunk a few inches into the ground to improve stability.

I used 3″ square fencing posts for the corners and 2×1 battens to stop the sides bowing under the weight of the growing medium. The posts are internal to the corner so the boards are screwed into the post as nails may pull through in years to come.

One good idea is to have a finial decorative ball fixed on the top of the corners, like they use for the main posts on stairs. Not only do they look really well but they help when you pull a hosepipe through to a bed, stopping it from dragging across the plants.

How to construct a raised planting bed

My first two raised beds on the new plot

Now, and this is important, before you put the wooden frame into position you need to double dig the bed removing and perennial weed roots and incorporating lots of organic matter like compost or manure into the base of the trench. Break the soil up well as you do this.

Now position and level the base using a spirit level. Allow the soil to settle for a few days and then incorporate compost into the top bringing the soil level up to about an inch or 25mm below the top of the boards. Your raised deep bed is now ready to plant.

Paths Between the Raised Beds.

Once the beds are in place it is time to complete the paths between them. Level them out and compact them if loose. A shuffle walk up and down can do this. The easiest thing to do is to buy some porous weed suppressant fabric material. Cut to size and lay over the paths and then cover with bark or wood chippings.

I have seen paths made from concrete slabs, if you use these check the sizing accurately when you position the beds and save yourself a lot of work later. Other materials you can use are decking boards, gravel and even block paving bricks.

My Own Feelings on Raised Beds on an Allotment.

Growing as I did on heavy clay, I think raised beds can offer a great way to grow but the expense in both time and money is considerable.If you have a good, well-cultivated soil then raised beds offer little or no advantage overall compared to convention cultivation.

Also I don’t think they are ideal for crops like potatoes, Jerusalem or globe artichokes and sweetcorn. Neither do I think they offer any significant advantage for growing broad or runner beans. They are brilliant for root crops like carrots, salsify and parsnips because they offer deep fine soil. They also work well for a salad bed, turnips and beetroot.

I wouldn’t turn an entire allotment over to raised beds but I certainly would have some on the plot

For a list of benefits and drawbacks of raised beds see part one of this article: Vegetable Growing in Raised Beds

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