Making new raised bed edges

Hello everyone,

I am not exactly a beginning gardener, but I had a hard time figuring out where this post should go.  I have a garden bed for which I wish to make raised edges.  Part of me just want to go out and get some 2x12's, cut them to length and drop them in place.  Obviously, these will rot over a fairly short amount of time.  I am left then with two options.  1)  Let them rot and add the rot back into the garden bed and build more garden edges, or 2)  protect the wood somehow from the rot.

I know I could go get some PT lumber, but it is both expensive and I am skeptical of having these chemicals in my garden (even though I know that new PT lumber is a far cry from the old arsenic based PT lumber).  Any suggestions on how to preserve regular pine without breaking the bank or poisoning my garden bed?

Thanks in advance,

Eric

I wonder what the feasibility of growing mushrooms on a border log is.

Hi Eric !

I would agree , stay away from the PT . You can protect natural wood without using a poison or paint by using the black plastic material used to protect foundations. Home Depot has it . I believe it is called Platon ( at least that is the name in Europe where I last got it). It is good because the surface is full of indentations that allow breathing and it is designed to be buried and allow breathing without being a toxin that might leach into your soil. You will find it close to where they have roofing and insulation.
They sell it in rolls of varying width, which you could just cut in strips. I have used it alot to line stone bed curbing . It will also be easy to nail to the inside of your 2x12 before you put the soil in. YOu could afterwards treat the outside of the boards with something paintable, even an oil based stain would protect that. They will last a long time .
Another tip would be to use short ( say 2" ) pieces of rebar as spikes driven into the ground tight to the outside of the planks to help keep them upright. Just make sure they are pounded down enough that they don't stick up and become a hazard.

Hope this helps.

A borax solution can be used to treat wood without poisoning the soil.
To do this you have some options on how to apply the borax solution, dunk and soak or multiple brush or roller application.
If you build a trough you can fill that with the solution (1 gal. water to 1 cup borax soap powder) and soak for 1-2 hours then let air dry prior to use of the wood.
If you use the roller or brush method you want to use the same strength solution and apply to keep the wood wetted until no more soaks into the wood, treat all sides and ends the same.

This treats wood for termites, carpenter ants and fungi resistance

Redhawk

Depending on how pretty it needs to be, you could use sections of logs as your borders.  They will take a lot longer to rot through.

Another thought would be to get some "slab wood" from a sawmill.  It's flat on one side and bark on the other.  Use the store bought pine for the raised bed and use pieces of slab wood on the inside of it (bark towards the dirt) to be the sacrificial material.

Good idea Mike Jay, I'm going to use some cedar tree logs for at least one raised bed surround this year.

I have an alternative to a raised bed. The reason for the raised bed is to improve drainage, or to cut down on the bending.

With this method you double dig the edges. Either remove the soil down double deep, or fork it and add a nice layer of mulch, or manure. Water what you've chosen to wash it into the fork holes if you chose to fork. When I've done it I took out all the clay from the double deep trench that I dug one spade width wide. I added enough sand, peat and manure to the whole garden so that I just threw what was the top spade depth soil back into the trench. When I was done the garden is on the same level as my surrounding lawn. So instead of getting the drainage out of a raised bed you're getting from a french drain. You could also dig a hole on the low side of the garden, but I elected not to do that.

If you need the height because of physical difficulties, like I have, then you should consider the work required to build that structure and then haul all that soil to fill it. In either case you're going to disturb the soil, less with this suggestion. If you do go with the raised bed solution then consider altering the height to allow you to dump your wheelbarrow over the top.

Thanks, I got the idea from my uncle who runs a community garden.  He got a free load of pine logs donated and just put the beds where he wanted them.  He's in a drier climate so they'll last him decades.

I once used oak slab wood that I'd cut off a log with a chain saw to build a hot frame. I put the smooth side in as I didn't want to have to dig it out every spring and deal with the irregular sides as I dug. It didn't last very long. Can't remember but it was either red or white oak, cause that's what grew there.

Of course using Naturally rot resistant wood, whether logs or planks or slabs is likely the best long term. Cedar , hemlock or cypress  depending on what is available locally.

The biggest advantage of the raised bed is apart from the drainage and back saving aspects , they also are less prone to pests and warm up faster than the rest of the ground in the spring. They are also easy to cover or convert to a mini hoop greenhouse on demand.

Thank you everyone for so many great ideas,

Regarding the logs as borders:  All of my beds had log borders, but they are approaching a decade old and are starting to show their wear and tear.  In two of my beds I actually broke up the remainder of the logs that were still left and dug them into the bed as a sort of hugel-light technique.  My remaining beds likely have a few more years in them, but they too will decay away at some point.  I don't want to go and chop down perfectly good hardwood trees to use them for garden beds so I was wondering what other options were available for 2x lumber.  Everyone here has given me some great ideas.

Redhawk,  I have heard of the borax-as-preservative before, but always in the context that it was water soluble and therefore transferred out of the wood (where you do want it) and into the soil (where you don't want it).  Is there any truth to this?  As a solution to this I have heard of people using the borax and then covering with either paint or tar like driveway sealant.  I am interested on yours or anyone's thoughts on this.

Again, thanks in advance,

Eric

If you use dimensional lumber try treating them with fire....Shou Sugi Ban style!

Another suggestion would to use repurposed metal roofing. Use it in place of the wood and use rebar to hold it upright.

Of course , if you find wood rots to easily in your area , maybe you can  get some cheap reclaimed concrete block, clay brick or natural stone. Lego for adults !

Make sure you tamp the base well and even without mortar the masonry material will stand up well , store heat and will never rot !!

I work as a stonemason and often make bed edges out of concrete and steel reinforced stone but this over the top for your purposes. We are useually trying to hold a bank back.

Just to add to the above post/photos.

Masonry solutions are good because its easy to make curving shapes  as you see here. THis is like one side of a raised bed.

You can lay out block ,brick or stone in any shape you want and can either use it "dry "  or cement it all together.  1 part portland cement to 3 parts sand and water to right consistency and you got it.  If you want extra durability lay steel mesh/rebar out in the bed in the bottom.

I find in most areas there is always stone or other materials available for free or low cost and you will know best yourself what you can get.

Even if you buy cinderblock they are only about $2 each. And can be finished on the outside with mortar or stucco with pigment.

The best thing about masonry for bededging is Rot resistance  and Heat storage.  

I used 2x4 stacked cedar boards with heavy duty deck screws to build 8" tall raised beds.  I stapled weed barrier fabric on the inside face.  They look good, were cheap, and easy to build 4'x8' beds.   7 years old now and no noticible exterior decay.  I even took several of them apart and reused the lumber 3 years ago to reconfigure into different sized longer beds.  I wouldn't buy pine boards and take the time to build boxes.  Not even sure I would re-purpose old pine boards for this purpose.

Logs are going to last many times longer than cut boards. Even pine will last quite a long time if you don't cut across and expose the grain.  Each layer of growth on a log is another layer that water and organisms have to penetrate before they can attack the underneath.
See if someone in your area sells cedar fence posts. They'll last many years even in contact with the ground.

Eric Hanson wrote:Thank you everyone for so many great ideas,

Regarding the logs as borders:  All of my beds had log borders, but they are approaching a decade old and are starting to show their wear and tear.  In two of my beds I actually broke up the remainder of the logs that were still left and dug them into the bed as a sort of hugel-light technique.  My remaining beds likely have a few more years in them, but they too will decay away at some point.  I don't want to go and chop down perfectly good hardwood trees to use them for garden beds so I was wondering what other options were available for 2x lumber.  Everyone here has given me some great ideas.

Redhawk,  I have heard of the borax-as-preservative before, but always in the context that it was water soluble and therefore transferred out of the wood (where you do want it) and into the soil (where you don't want it).  Is there any truth to this?  As a solution to this I have heard of people using the borax and then covering with either paint or tar like driveway sealant.  I am interested on yours or anyone's thoughts on this.

Again, thanks in advance,

Eric

The active ingredient of borax is boron, when you soak a board so that the boron gets into the wood at least a quarter inch, it becomes deep enough that it will not leach out easily.
Even if the boron does leach from the wood it will remain in the soil and do the job of deterring fungi and termites and boron is one of the important trace minerals, so unless you were stacking many borax treated boards in one spot you really don't have to worry so much.
I even use borax, dissolved in water to pour around our wood fence posts, the grass that grows in those areas is very healthy, tough and has very deep roots, all good things.
You could paint treated wood, but if your going to go to that much trouble you might as well use the ground contact treated lumber since you are encapsulating the boards anyway.

The thing about wood that decays, it becomes nutrients for the soil as well as humus in the soil. We have many beds that we bordered with lumber made from blow down trees from my cousins land that are rotting into the garden beds.
This year we are going to use concrete blocks that we have laying around to make the new border by just placing them on the outside of the current disappearing boards.

Redhawk

We just finished building our kitchen garden and decided to build raised beds using cheap local pine timber (pallet boards) treated with shou sugi ban. It was our first attempt at this so there was a good bit of trial and error. It also took a lot of time to treat the boards with the blow torch and then assemble them, but I think it's worked out nicely and once I got into it, the shou sugi ban process becomes very meditative and creates beautiful patterns as you burn the wood. In the past we have built raised beds with no sides and they worked perfectly but the owner of the property shares the view of the kitchen garden with us and we didn't want to give the wrong impression of permaculture

My personal experience with raised beds has seriously put me off using solid edges (wood or stone). In our vegetable area, which we inherited from the previous owners, they had installed raised beds with wooden bed edges.

1) The edges rotted pretty quickly, despite presumably being treated.
2) While they were still structurally sound, the acted as habitat for a huge slug population
3) Weed roots - including our very worst local weeds, creeping buttercup and bindweed - made a home in the cracks and soft patches of the rotting boards. No matter how much weeding we did they quickly spread back in.
4) As they broke down we started trying to remove them, and are still finding lost pices of metal work from where they had secured it together.
5) They had originally intended that the paths between the beds be grass, but had spaced the rows slightly too close together so that the mower couldn't get through. This made maintenance a real chore.


Over time I have gradually been ripping them out and turning the path area back over into planting spaces. This works much better for our purposes than having fixed raised beds. In our climate any permanent path area rapidly turns to a dense sod of grass and weeds, increasing the maintenance.

I know that many people swear by them, but for us they have been a hinderance rather than a help.

In my previous gardens, I preferred raised beds with no edges mainly because they are a lot less work. I'm hoping my shou sugi ban board edges will work against rot and termites; it's an experiment so we'll see how successful it is. I'll be putting eucalyptus woodchips down in the paths (from neighbouring plantations) - hopefully the allelopathic properties will keep the weeds down so no need for a mower in there and luckily we're not in a very slug-prone area so I hope they won't be a problem.

Walt Chase wrote:Another suggestion would to use repurposed metal roofing. Use it in place of the wood and use rebar to hold it upright.

This is really effective and durable. Metal tee-posts or lengths of scrap pipe work as well as rebar if that's what you have.  One potential problem: the upraised metal edges are a safety hazard.  Any time you stumble or fall in your garden, and you put out a hand to catch yourself, or fall across your raised bed edge, that edge is a blade that can cut you quite badly.  

A quick solution is old garden or irrigation hose sliced open and slipped over the sharp edge, then secured with a few short screws.  It's not pretty but it works.

A much better solution is to make a wooden top rail out of a wide flat board (2x6 or 2x8 is ideal for this) with two downward-pointing parallel boards screwed or nailed to the underside (2x4 or 2x6) that you simply slip down over the sharp metal edge to sandwich the metal.  (This also adds a lot of stiffness and strength to your bed edge.)  I find that having a railing around my beds (which I make pretty high) is very convenient as a place to set pots, tools, seedlings, my beverage, produce, or my hand when I'm levering myself back to my feet after kneeling.  Because it's high and dry and lacks soil contact, unfinished lumber is fine; but a coat of linseed oil or your favorite vegetable oil finish will add beauty and durability.

Mark Deichmann wrote:Masonry solutions are good...

I find in most areas there is always stone or other materials available for free or low cost and you will know best yourself what you can get.

This would be my dream.  But it must depend, I think, on where you are.  Locally there's nothing inexpensive.  Every masonry product has an expensive per-unit price at the building supply, and folks doing demolition seem to have a keen awareness, because their salvage prices approach the new prices.  We have a local brick plant and even the salvage brick prices are not as much cheaper than new brick as you would expect, given the amount of labor involved.  I'm always watching for the right deal!

Joe Black wrote:We just finished building our kitchen garden and decided to build raised beds using cheap local pine timber (pallet boards) treated with shou sugi ban. It was our first attempt at this so there was a good bit of trial and error. It also took a lot of time to treat the boards with the blow torch and then assemble them, but I think it's worked out nicely and once I got into it, the shou sugi ban process becomes very meditative and creates beautiful patterns as you burn the wood. In the past we have built raised beds with no sides and they worked perfectly but the owner of the property shares the view of the kitchen garden with us and we didn't want to give the wrong impression of permaculture

Hi Joe,

May I ask for an update on your shou sugi ban garden beds a few years after please? Thank you.