Wednesday, February 1, 2012

Construction Method of the Week: Tire Beds

Community gardens face various issues when starting up. One of the major issues can be building raised beds. Raised beds have many different advantages. For example, we use ours to improve access for members of the community that have knee or back issues. We also use ours because the soil in Escalante park has the density of asphalt when it is dry out (there are also some pH and nutrient issues). This forces us to only plant our vegetables in raised beds.

The ubiquitous wooden raised bed is nice. It looks good, it holds up well to the elements, and it is easy to build. Unfortunately, they are quite expensive. The most logical setup (in our humble opinion) is to build a 4 foot by 8 foot bed since lumber is sold in 8 foot segments. This minimizes cuts and wasted lumber. Even with this cost cutting measure , our basic model adds up to over $200 each:

Now these beds are nice and they should pay for themselves eventually, but the cost of these beds really add up quickly. So if you are looking at starting up a garden and don't want to wear your fingers to the bone grant writing, it would be nice if there were some other options.

Our first strategy is tires:
We got this pile just by asking nicely at a few tire shops around the Valley. These tires can be stacked into various shapes and are very easy and inexpensive to set up. The big questions that remain are the durability, aesthetics, and ability to grow plants in them.

In regards to durability, we have been growing in one set of tire beds for a year now. This means they have outlasted two generations of straw bale beds. The tires have slumped and settled a little, but in other respects are structurally sound.
As you can see from the picture, we painted the tires. We did this for a number of reasons. The first is that it is fun to give children paint (provided you can send them back to their own parents after). Second, painting the tires makes them look less like a pile of tires and therefore makes your garden look slightly less like a landfill. Finally, we worried that the black tires would absorb too much heat and burn the plants growing in them. As you can see above, this was the middle of summer and the plants growing in the tires grew quite well.

The last issue I have heard is that tires have various heavy metals in them that could leech out into your soil and get into your plants. This would be very bad. However, I have not found any sources that record this happening. Also, used tires have gone through some extreme situations while attached to their respective cars. This includes huge temperature swings, being pressurized and having multiple tons of metal resting on them. So I am willing to wager that any volatile chemicals in them would have been leeched out or burned off by now.

Overall, these tire beds seem to be the most economical way to build raised beds. The only downsides are that you are limited in height and that some people may not like the look of them.

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