Raised garden beds allow a garden to be planted almost anywhere! The concept dates back to ancient cultures in 300 b.c. Pre-Hispanic cultures in South America from Columbia to Bolivia employed the raised bed concept waru waru to prevent erosion and improve irrigation. Other methods like hügelkultur have been used for thousands of years and also apply the concepts of raised bed gardening. In medieval times beds were edged with wattle fences. Fast forward 500 years, the Parisian market gardeners of the 18th Century built up their plots using horse manure that was abundant during a pre-motor vehicle city. Raised beds have always been a popular method of gardening because of their manageability.

RELATED POST: How to Fill a Raised Garden Bed Using the Hügelkulture Technique

UNTREATED WOOD

Pressure treated lumber is not any stronger than untreated lumber. While pressure treated lumber will resist the elements and rot better due to added chemical preservatives it comes with many concerns. Wood treated with CCA or chromated copper arsenate can leach arsenic, a very toxic compound. Plants growing in the garden bed could potentially take up the chemicals making it unsafe. Untreated wood is the safer, more environmentally friendly choice.

SOFTWOODS

Pine (southern yellow pine/common board), Douglas fir, spruce, and juniper. These softwoods are cost-effective options, but not resistant to rot. They will need to be repaired or replaced within 3-7 years depending on climate.

HARDWOODS

Cedar and redwood are the best choices of wood for garden beds. These are durable, naturally resistant to moisture, rot, and termites. They are known to last 10-20 years. Oak, cypress, teak, beech, hemlock, and walnut are other long-lasting hardwood options. Hardwoods are a long-term investment.

HEARTWOOD

For the best of the best choose the heartwood of the hardwoods mentioned. It’s the most durable and long-lasting lumbar. Although even more expensive, they could last over 20 years! Heartwood is the densest because it comes from the center of the tree. It’s the dead wood that doesn’t feature channels for xylem and phloem, making it more resistant to water and infestation compared to sapwood. 

NOT RECOMMENDED

•  Railroad ties. The wood is preserved by soaking it in creosote, which is composed of over 300 chemicals, many of them toxic and persistent in soil. Exposure to creosote has been shown to have adverse health effects.
•  Reclaimed wood. Only use reclaimed wood if you know the type and if it has been treated or not.

Dimensions

Supports

⋆ Stainless steel metal brackets are a good choice too. You can get straight brackets for the mid/quarter points and corner brackets for the intersections.

ANCHORS

To further the support of the garden bed you can create anchors and dig them into the ground. Alternatively, you could dig the entire bed a few inches into the ground. Personally, I don’t find anchors necessary.

Placement

Weeds & Critters

HARDWARE CLOTH

If you have underground critters like gophers, moles, and voles I would recommend stainless steel 1/4″ hardware fabric to keep them from burrowing into your bed. 1/4″ will keep critters out but still allow root systems to travel deeper.

Tools

SCREWS

Screws are what is going to hold the bed together, so it’s an important topic! When deciding what size screws to get the general rule of thumb is that the screw should enter at least half the thickness of the bottom material.

You’ll want to use exterior deck screws because they are made to endure the elements. Some exterior deck screws are not suitable for cedar or redwoods. Coated galvanized screws are susceptible to the tannic acids in these hardwoods.

Stainless steel screws are my #1 recommendation for garden beds because they are not only an excellent environmental choice but also an excellent economical choice. They can be used on any wood including cedar and redwood. The screws are not coated with toxic materials and do not produce toxic off-gas or leach when they are in the wood. Plus, stainless steel is naturally rust, tarnish, and corrosion-resistant.

⋆ Screws with star (torx) and square (robertson) drive recesses resist stripping better than Phillips-drive recesses.

When I built my three cedar compost structures I missed the fine print that the exterior screws I bought were not meant for cedar or redwood. I ended up having to replace 250 screws… learn from my mistake!

OTHER TOOLS

•  Power drill – you could also use a hammer and nails, but screws outperform nails because they have more tensile strength. Tensile strength refers to a material’s ability to resist breaking under pressure.
•  Miter saw (preferred) or circular saw – an alternative is having the lumber supplier cut the wood for you!
•  Clamps – to hold the wood together while screwing.
•  Saw Horses (or any flat surface)
•  Measuring & Marking Tools – t-square, measuring tape, and a pencil.
•  Staple Gun and SS Staples if you choose to add hardware and/or weed cloth.
•  Safety Goggles for protection.

Build a Low-Cost
Raised Cedar Wood Bed

Using cedar fencing and rough cedar to make a garden bed is actually less expensive than using pine! Cedar fencing is only 5/8″ thick but as long as the bed is supported this rot-resistant wood will last a long time. Rough cedar (used for the supports) is also a less expensive option because it is wood that hasn’t been planed.

Cedar fencing is 5.5″ wide and 6′ long with dog ears on one end. If you are not fond of the dog ears they can be removed by cutting an inch off, but I don’t mind them. Below, I am creating a 3’x6′ long bed that is 27.5″ tall using seventeen cedar fence boards and two 2″ 4×8′ rough cedar boards. I wanted something easy on the back so this bed is a little over 2′ tall. The shorter the bed, the fewer boards you will need to purchase.

Step by Step

1

Cut the Wood

To keep it simple I am working with the dimensions already available at the lumbar yard so I don’t need to make any cuts for the long sides. For the short sides, I am cutting five boards in half making them 3′ each. For the supports, I cut the rough cedar boards into pieces that are the height of the bed. In this case, each one is 27.5″ long – the exact height of five cedar fencing boards stacked on top of each other. Now I have six support beams. One for each corner and both midpoints.

2

Create the Sides

3

Create the Front & BACK

Now that the short sides are made stand them sideways across from each other and lay the long boards across. Because these fencing boards can be a bit wonky I flip and swap pieces until they align adequately before I secure them. Once they are aligned they can be secured with screws. Repeat this for the backside.

4

Affix the Midpoint Supports

To prevent bowing (especially because cedar fencing is only 5/8″ thick) add a support beam at the midpoint of the front and back (long sides).

5

Secure the Hardware Cloth

RELATED POST: How to Fill a Raised Garden Bed Using the Hügelkulture Technique

⊙