The Simplest Raised Garden Bed
For backyard gardeners who live in gopher and snail-infested country, it seems like raised garden beds are the way to go.
But what is the simplest solution? What is most effective? Cheapest? Sustainable?
My first attempt at answering to these questions was to build two garden beds out of urbanite (broken up concrete) from other parts of my property. It was certainly sustainable, after 6 months it seems to be effective, and my only purchase was the hardware cloth (wire mesh) that I used to line the beds. But though breaking up the concrete, moving it, and assembling it into garden beds didn't require much technical expertise, it sure was a lot of work.
Those who are handy with the hammer and saw can, of course, construct raised beds out of lumber (scrap wood that is bound for the dump is the most sustainable option, in my opinion). However damp soil is not the most forgiving of substances when it is in contact for wood for a long period of time (some call it decomposition), and even the most well-constructed wooden garden box won't last much longer than five or ten years, regardless of the type of wood you use or how it is treated.
Recently I discovered door number three: Used tires. Barring aesthetic distaste, they make the perfect raised bed for a small, backyard garden. With a hardware cloth liner and a band of copper strip, they become gopher-proof and snail-resistant. The black rubber helps to heat the soil, so you can start plants earlier in the spring. They come in an array of sizes, are easy to handle and place, work in small spaces, are durable, and even take a coat of paint, if so desired. And did I mention that they are free?--Tire stores must pay $4 each to get rid of them.
A gentleman named Charles Sanders seems to have written the definitive internet article on the subject, where he describes how to build composters from tires, grow potatoes, and create a multi-tiered terraced tire planter. Other sites have mentioned success with onions, tomatoes, berries, pumpkins, cucumbers, and cauliflower. Carrots and corn are cited as not being able to do as well in the heated soil being generated inside the black tires.
For those concerned about the chemicals in tires, I did a bit of research. The State of California Department of Education recommends against it, while both the Clark County Master Gardeners (Washington State University Extension) and the Purdue University Cooperative Extension do not have any reservations, with the WSU folks stating definitively that used tires do not release unwanted chemicals into the ground.
I found two more websites with additional information. See comments before installing tires in your backyard!
Comments
A very impressive garden!
I'm not so sure that I would use tires myself. Tires do break down and the chemicals have to go somewhere. If they don't go into the soil, where do they go?
Given the stench around piles of old tires, I would assume that they give off gases and question how good that is for the plants or the creatures that eat them.
Raised beds have their advantages in cold, wet areas and for jump starting early crops.
Raised beds definitely make gardening easier on the back!
I'm experimenting this year with flat areas and mounded areas. My black beans in the mounded area are sprouting quicker than those in the flat section, despite having been planted later.
It will be interesting to see the final results!
Posted by: Lyle | May 21, 2008 07:54 PM
I can take credit for finding the photo on internet, but I can't take credit for the garden.
As far are your beans are concerned, the mounds allow for more surface area to be exposed to the warm air, thus heating up the mound faster and promoting faster growth. The trick is irrigation--If you are watering with a hose a lot of water can run off the mound and be wasted. Drip irrigation is a good solution to this problem.
Like I said, I have read mixed reviews of the safety of used tires. Additional internet research revealed two more websites with information on the subject. One recommended using a plastic liner to keep the soil from contacting the tire. The Los Angeles County UC Cooperative Extension, however, tested the soils from urban gardens and did indeed find elevated levels of heavy metals in the soils, including cadmium, of which old tires are a possible source (http://celosangeles.ucdavis.edu/Environmental_Horticulture/Trace_Elements_and_Urban_Gardens.htm
). Though tests of leaves and fruit from these gardens did not indicate that the plants had taken up the contaminants in any "significant amounts," the study does caution that in highly contaminated areas, plants, especially leafy vegetables like lettuce, cabbage, and spinach, can absorb cadmium in roots, leaves, and to some extent in fruits. Soil pH, organic matter content, cation exchange capacity, and temperature can affect uptake of heavy metals by plants.
Cadmium occurs naturally in soil to 0.5 ppm, and in urban areas to 5 ppm. The feds set the "threshhold limit" at 20 ppm.
So I guess I have changed my mind. Based on the information in the article, while eating carrots growing out of a tire is likely perfectly safe, all other things being equal, it sounds like I am still better off eating veggies that are "tire free."
Bummer. And it seemed like such a good low-tech second life for used tires.
Posted by: Jeremy Miller | May 21, 2008 09:10 PM