DIY Pressure Treated Wood For Raised Garden Beds

Here’s how to make your own cheap rot-resistant wood for basic gardening raised bed projects.

A friend, who happens to be a technical paint expert and I were chatting over coffee one day about some diy garden construction I was about to take on (building a lot of raised beds) Rather than using chemical laden pressure treated wood, he suggested I use vegetable oil

This made a great deal of sense on the surface as the old farmers used to use linseed oil on wood to preserve it when buried (fence posts etc) but this is so expensive now, you won’t use it in bulk.

To be frank – this is NOT pressure treated. There’s no “pressure” applied to drive the vegetable oil into the wood.

But the title captures the intent of the post – to create a long-lasting wood that doesn’t rot and will last for long enough to be practical.

Any Special Instructions?

  • Nope. Use the cheapest vegetable oil you can find and slather it all over the wood. Fill up the cracks and knotholes with it. The oil will penetrate quite well (two coats is about all it will take) and dry in 24-48 hours if you leave it out in the sun.
  • Really soak it into the end grains where water can and will enter first and quickest.
  • Two coats are better than one but more than that won’t sink into the wood.
  • Hard wood such as bamboo (stakes) won’t absorb this oil so don’t bother with those.

How Long Will It Last?

Good question. The honest answer is we don’t know.

Summer 2013 I’m building raised beds now and using this system of diy pressure treated wood for our vegetable garden beds.

Update: Nov 2018  The few beds we use are fine.

Update: Spring 2021 I found the bottom board that had two sides exposed to the soil (side and bottom) tended to rot a bit on the bottom board where the water was the heaviest but was still serviceable. That’s 8-years. (I moved a bed and dismantled it so it was easy to tell.) The other boards with only one side exposed to the soil were in good condition.

Don’t use it in serious construction.
It won’t meet building codes where pressure treated wood is allowed.
So don’t.

The larger 12×50 foot raised garden bed made out of this vegetable oil treated wood

So What’s Our Thinking On This?

Our thinking (my friend and I) was that if it lasted only twice as long as untreated wood, we’d get 8-10 years out of each raised garden bed. And the price of rough construction grade wood – and a bit of vegetable oil – is far less than the price of pressure treated wood, cedar or even plastic.

So if we get 8-10 years – the odds are we’ll want to change or move the darn garden. And if we like the layout, it’s no big deal to pull apart a raised bed like this (use good deck screws that don’t rust) and replace it. The soil will mostly stay in one place after that time so it will be like reskinning the bed rather than doing a lot of digging etc.

It’s a simple way to get raised beds.

See updates above for how long will it last

Why Not Just Use Pressure Treated or Cedar?

Pressure treated wood is “supposed” to be safe with the new formulations. But the “old” formula was supposed to be safe too until they took it off the market. Call me skeptical about using pressure treated wood in my raised vegetable garden beds.

I know vegetable oil isn’t going to hurt me nor be a problem if it leaches a bit into the ground.

Using Cedar? Have you checked the price of that stuff? Lovely indeed and I built a deck out of it but it’s out of my budget for the number and size of raised beds I need to build.

Update 2021 re price: Covid has driven the price of all lumber sky-high and this is just another workaround to use the least expensive products for the longest gain.

Some Concerns Answered

It’s not really pressure treated That’s correct. There’s no pressure treatment at all – the oil is not forced into the wood. I used the title to help folks understand what I was trying to do.

“It doesn’t work” Here’s my response. First – oil in one form or other has been used as a wood preservative for some time. Creosote is one example, linseed oil is another – and yes, vegetable oil is a third. Vegetable oil simply happens to be easily obtained and relatively benign (unlike creosote) in the vegetable garden. It’s also the cheapest.

It won’t last for long. Probably not as long as chemically treated wood but I know that going in. I don’t expect it to last forever but I do expect to get a few extra years out of really cheap wood.

It attracts insects. Not so far. Haven’t seen anything out of the unusual or more than expected.

It stinks after a while.
Again, not so far.

Borax is better. Borax is a component of boron. A quick search showed two products advertising the use of this material. One was only registered for termite control while the second advertised termites plus wood preservative.

But here’s the thing – boron leaches out into the soil and this is clear on the labels. We can expect homemade borax mixes to do the same thing. The thing about plants is some are quite sensitive to excessive levels of boron and die or grow poorly.

So given this data – borax might indeed act as a wood preservative but it also has the potential to do damage in the garden when it leaches. Given this choice, I prefer the possibly shorter life of the vegetable oil soaked wood rather than the long term problem of possibly killing my plants. But to each their own.

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How To Understand a Landscaping Contract To Save Money

There are 3 important things in a landscaping contract (and as a consumer you really want one of these if there is major work being done).

  • First – those signing must have the ability to enter into a contract. In other words, you have to own the house or have the right to make modifications, you have to be of legal age etc.
  • Second: There will be a “consideration” – this is where the landscaper agrees to do certain kinds of work for a consideration – you paying them.
  • Third : Lawyers call it a “meeting of the minds” – a written contract about what will be done and not done and the associated costs involved.
Photo by Scott Graham on Unsplash

Note: This article should not in any way be considered legal advice. For any questions on this, please see your personal lawyer as state and provincial laws differ in many ways. This article is a general guideline only.

Why a Landscaping Contract?

The hard reality is that if a landscaper has been burned by customers in the past (an it only takes one or two and serious contractors quickly smarten up and expect contracts) then you can expect a contract. This should protect you both in the case of work that’s not done to satisfaction.

What You’re Likely To See?

Non-refundable deposits.

In some cases, a client will take on a landscaper, the landscaper will do a great deal of preliminary work and invest time and resources in the work before the actual landscaping will start.

But then, the client decides not to go forward and the landscaper is left holding the bag (and plants ordered and paid for etc).

So expect to make a commitment on this.

Payment Terms

Your landscaper will likely want a series of cheques as the project progresses and agreed on timelines are met and accomplished.

It is up to both parties to agree on those steps and how they are to be measured.

The larger the landscaping contract, the more important this provision will turn out to be.

Novice gardeners may find themselves surprised at how this works but landscapers will make sizeable investments in plants, time and resources to get a project underway and they usually want to make sure payments are coming in on time to fund the work.

Always get a hold-back amount (often 5-10%) of the landscaping contract until all work is done to your satisfaction no matter how much is being paid out during the work period.


  • A deposit of 20% is common on landscaping contracts.
  • Second payments: Some landscapers ask for another 50% on starting the project. This is negotiable.
  • Final payment: this is usually within 15 days of completion but sometimes 30 days.

Changes to the Design

This is a major problem for landscapers and a source of frustration for many clients. Often in the middle of a project, the client will say, “Don’t do that – do this instead”. And not realize the extra cost involved in “this” compared to “that”.

Some landscapers work this out on the fly but don’t be surprised to see a “change order” section of the landscaping contract that deals with the how and what of changes to the original order.

Many landscapers will also charge an administration fee for every change you make during the work as these changes cost them money to do. (You change your mind about how much brickwork you need and the landscaper now has too much brick or too many trees or not enough trees and has to absorb more shipping charges)

These change orders are important and can add up to significant numbers in a surprisingly short amount of time.

Warranties and Guarantees In Your Landscaping Contract

You want them! On both plants – and hardscape.

Sometimes the landscaper will balk at a full plant guarantee because they have no control over how (or if) you water or feed your plants. Negotiate. Most landscapers will guarantee woody plants for a year- but not perennials.

There will often be a clause that if the plant died from neglect or mismanagement (you whipper snip the base of a tree) the landscaper will not be responsible for replacement (and rightly so in my mind – you kill the tree in some way, it should be your problem not somebody else’)

One thing to have clear is who pays for installing the replacement plants?

Have this spelled out in the contract to avoid misunderstanding.

Hardscape warranties are a little harder to negotiate on your behalf. Problems with hardscape (brickwork) etc take a few years to develop as ground settles and drainage issues surface (or not).

Phone around to other landscapers in your area to discover the average length of time they offer. Try to get your landscaper to go beyond this number if possible but you may simply settle for the area average (your landscaper will be working to the competitors numbers)


There will be legal language relating to liens the landscaper will apply if you don’t pay or if there are problems. This will vary from legal area to other areas and the only way to know if they are correct is to get a legal opinion.


The contract should spell out clearly who is to get the necessary permits.

Without this, you could find yourself in a pile of trouble right away. Small projects aren’t usually a problem (fill out a single form – pay a charge – move forward) but larger projects that involve construction or water/electricity etc might involve drawings and code work and a ton of paperwork.

Get it spelled out who’s responsible.


Here’s a really important but little understood issue. Somebody has to mark the utility lines if they’re buried.

Somebody has to mark sewer and electrical lines if there’s to be any digging,

Mess with those and you’re into big bucks as you’ll be responsible for any damages caused by lost power or sewage flooding!

Spell it out in the contract who is going to do this and who is responsible for any damages.

Get other practical landscaping tips here.


There is often legalese at the bottom of a landscaping contract that gives the landscaper rights to collect or not lose rights. Your lawyer will advise what this means.

Again, this article is not legal advice and any concerns you have should be dealt with by a lawyer in your area.

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