Raise Beds Or Not To Raise Beds?

June 5, 2012

The decision whether to have raised beds in your garden may seem obvious, as they're very popular right now. But it really should depend on your situation and soil type, because there are some instances where you should not use them.

So let's look at the pros and cons of the matter.

Pros:

Better drainage -- in areas with poor drainage such as wetlands and areas with heavy clay soil, raised beds are the best choice.

Solves soil problems such as dead or contaminated soil -- just set up a raised bed and fill it with clean compost and you're ready to plant

High raised beds (when filled with sufficient mass of soil) can be warmer simply because heat rises. This is the place to put your plants which are just a bit out of their planting zones. Dark-colored building materials work even better.

Raised beds (when constructed properly, of sturdy materials) offer easier access to your garden and plants, and can be very useful for gardeners who can't get up and down easily.

Cons:

Raised beds dry out quickly, and may not be the best choice in sandy soil or severe drought

Narrow raised beds can freeze in severe cold, killing your plants.

In both these situations, sunken beds may be the best choice for your garden. In severely cold areas, combine sunken beds with other frost protection methods http://www.edible-landscape-design.com/protecting-plants-from-frost.html and make certain to get the base of your bed below the frost line.

Design considerations:

Raised beds can be beautiful or they can be hideous. Like every other gardening method, it's all in the materials you choose, the care you take in constructing them, the design you use, and how you plant them.

Try to get away from the "cheap boxes in a row with weeds" look at all costs -- it's better to have one good-looking raised bed that you can handle than four shabby ones.

Raised beds do not have to be square, or even rectangular! I've seen great-looking triangular, round, and hexagonal raised beds. Experiment with different materials such as stone, brick, sealed wood, metal ... whatever you have on hand.

Need help constructing your raised beds? You can get reviews of local contractors and designers through Angie's List -- learn more about Angie's List here.

You can find local professionals who specialize in edible landscaping in my Edible Landscape Business Showcase.


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Comments for Raise Beds Or Not To Raise Beds?

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Jun 12, 2012
Re: Raised Beds Or Not To Raised Beds?
by: Susan Adams

I enjoyed your article on raised beds! Everyone wants them right now, but I agree that they are not always the best solution.

I do think you left out an important warning though. Treated lumber. I come across lots of beds constructed of pressure treated lumber, these woods leach nasty chemicals into the soil and are not suitable for growing edibles in or around.

Unfortunately the treated lumber is cheap and technically holds up longer -- but also may be leaching poisons into your food! Instead of using "whatever you have on hand" if my clients want a wood bed I always encourage them to use cedar or douglas fir for a longer lasting non-toxic bed, or untreated pine (if budget requires) with a homemade non-toxic wood sealant.

Susan Adams
Owner
Simple Roots Edible Gardens

My answer:

Hi, Susan --

I totally forgot about pressure treated wood ... I guess I shouldn't have taken it for granted that people understand about that.

Jun 12, 2012
Pressure Treated Lumber changed...
by: David Silvan

I believe if you check the EPA studies you will find that some alarming findings were discovered back in the 1990's about toxic chemicals in CCA (chromated copper arsenate) pressure treated lumber leaching poisons in the area immediately around them. For example, this was discovered to be a problem in areas with playground equipment leaching arsenic into dirt immediately around pressure treated posts.

After this, the lumber industry did a voluntary change in about 1997 to a new ACQ (alkaline copper quat) based treatment with higher copper content, which is deemed safe by the EPA since none of the chemicals used are considered hazardous or carcinogenic. One nice side affect of having lumber with such a high amount of copper in them is that slugs tend to shy away from them, which is a huge plus in my yard.

I carefully researched this and decided to build many of my raised garden beds using the ACQ pressure treated lumber.

My answer:

Hi, David --

Thanks for this thoughtful answer ... I'm sure that in many countries pressure treated lumber is safe.

However, since I have readers in countries which may not have as strict standards as the country you're in (and have readers who may be using old wood for building which might not be up to these standards), I feel that people should be aware of the possible dangers and do their own research just as you have.

Thank you so much for posting this.

Jan 25, 2013
Raised beds
by: John

This past Spring, I used a Chillington ridging hoe to make raised rows (too cheap to build beds) in my dad's garden... Long story-short, the garden produced better than it had for the last 35 years. It required less weeding & watering... The rows were mounded about 18" tall so weeding required less bending.

If you've never used a ridging hoe, I strongly suggest you spend the money and buy one! (your lower back can thank me later)

I bought my hoe online from www.easydigging.com Serious gardeners will appreciate the quality of this tool. I wish I had known about it 40 years ago! This tool will be passed down to my grandkids. It is awesome!

Thanks for the tip!

Mar 21, 2013
Not to raise
by: Sue Craske

I got my first allotment 30 yrs ago and put in raised beds, mainly so that the kids could run along the paths rather than all over the beds. I also made an L shaped pattern which was quite maze like for little ones. It also seems less back breaking to deal with a finite bed than an expanse of weedy soil.

However like you suggest, I think they dry out our poor chalky soil too much (Brighton in the South Downs). I think the patterns you can make with 1.2 metre widths is good (the optimum width to avoid the temptation to tread on the bed), but I prefer to just have slightly mounded forms without wooden sides to hold up the soil.

Also while constructing my current very slopey allotment
(http://www.flickr.com/photos/suecraske/2073606740)
I dig down to form the paths and tossed the excavated soil into the new beds. This prevented the paths becoming a foot higher than the surrounding soil which you often see on allotments. Continuous digging over the years eventually lowers the soil height, though I do suspect that grassy paths also gradually increase in height from debris.

You can see this with ancient field systems on slopes, where the ploughing makes the soil slump away from the next terrace above.

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