Wednesday, March 26, 2008

raised bed design and construction

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While I wait for more sprouts and planting, I'm posting some information on my raised beds.

My husband made the beds about 10 years ago from boards of 2x6 pressure treated lumber (oops! Don't use pressure treated lumber for your gardens, although the newer types may be safe. I'll add a link soon about the hazards of this in gardens). They measure 3.8 ft by 9 ft. I have five adjacent beds. Between each is a pathway that ranges from 15 to 17 inches wide, but you might want to make them wide enough for your rake (I use an adjustable rake).

To make the beds, my husband just laid the wood on the surface of ground. He made stakes (about 2x2x12) that were pounded into 3 of the 4 corners of each bed. The frame is screwed into these stakes. The stakes hold the beds in place.

After making the frames, we filled them with about 3 or 4 inches of a mixture of peat, composted manure and topsoil. All were purchased in bags. I turned this mixture to mix it with the soil below. As I remember, it took me a few years to get the beds full to the top - they hold a lot of soil.

I have a nice composting system where I compost most of my garden waste. Every year a good amount of this goes into the beds and is turned under along with the cover crop that I've planted for the winter.

The raised beds work great and look nice. Well, most of the year they look nice - right now they are quite a mess....
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garden structures


Anonymous said...


This is useful information! Thanks

alec said...

kathy- interesting. i sent you another email.

Anonymous said...

There are a lot of health and safety concerns over the use of treated wood, especially near a vegetable garden.

You will find a lot of conflicting information on this, especially because the wood companies like to promote their products as safe, but mostly the advice is to avoid buying new treated wood and when the treated wood you are currently using needs to be replaced look for a non-treated alternative.

The fence going around my garden is made with treated wood, and I think that's pretty common. When you actually use treated wood in your garden, the chemicals can easily come out and be absorbed by the plants. I understand the chemicals come out faster in the first couple of years, so because your wood is 10 years old now there may not be many chemicals left. I personally would look for something else to make raised beds from.

Good alternatives are plastic lumber (which is often made from recycled materials) and naturally rot resistant woods like cedar. You can also make raised beds out of materials like bricks or rocks.

One of the problems we have around here is that treated wood is not clearly labelled, so sometimes you end up buying it by mistake. Modern treated wood usually has a greenish color.

kathy said...

Thanks Patrick. I wondered about that. The greenish color is noticeable. I'll consider replacing them sooner rather than later.

kathy said...

I'll also test for arsenic that is leached from pressure treated wood.

In reading about pressure treated wood problems just now, I also see that arsenic is also a big problem in vegetable gardens located on old orchard sites because of the pesticides used. Yes. That's me. Our house part of a development build in 1922 in an old apple orchard.

Anonymous said...

Being new to gardening and using raised beds, I had built my beds using pressure treated wood. Unfortunately, I didn't realize my mistake till after the fact. As a result, I decided to paint the inside of the boxes and line them with heavy duty plastic. I figure it is better than leaving things alone.


Anonymous said...

I worked in the timber industry for many years. The treated timber is treated with 98% arsenic. It is in the process of being banned in many places, especially children's palyground areas. Very deadly stuff.


heydave said...

The old style of pressure treated had arsenic, the new stuff does not.

Anonymous said...


I think some science comments on this issue would alleviate some fears of the wood and its real danger.

See the link below and the link within that posting as well.


Anonymous said...

My apologies.

Here is the link.


Unknown said...

Fences are good for garden. I prefer garden fences than concrete fences. You must always study about fences and their maintenance. The blog was good to give some insight about timber garden fence panels.
treated timber depth of rail