Summer Garden Madness - the Arizona Raised Bed Method

Yeah, I went nuts today in the backyard. We aren't supposed to plant our summer crops here in Phoenix until March 1, but we are having a warming trend already, so why wait??? I planted corn, watermelons, pumpkins, cucumbers, beans, okra, peppers, onions, turnips, and leeks.

I also invented the Phoenix Raised Bed Method. It is a take off on the French Bio-Intensive Double Dig Method. In the Bio-Intensive Method, you dig down a shovels-worth, remove the dirt, then dig again, before replacing the original earth. Thus, you have up to 1 and a 1/2 feet of loose soil to plant in.

Well, in the Phoenix desert, the farther you go down, the harder it gets. Once you get past the sandy dirt layer, you might just hit caliche, which is literally rock hard. Not the mention all the actual rocks you will have to dig out. In other words, digging down sucks. So here is what I did:

I tilled the ground pretty good, producing about 8 inches of soft fluffy soil. Then, instead of continuing to dig down, a la the Biointensive way, I started shoveling UP, making big piles of soft earth. In other words, removing about 6-8 inches of top soil, and putting it right on top if the soil next to it. I then leveled off the top of the pile, leaving little berm walls around the edges for flood irrigation.

Viola! A foot and a half deep garden bed of soft fluffy soil for the plant roots to luxuriate in. I added some blood meal (for nitrogen) and garden sulfur (to lower pH) for good effect.

I created one big plot that way, about 6x8, and four smaller plots, about 2x6 each. Here's a pic of the smaller ones.

Raised Bed Gardening in Phoenix

If you have the money to set up the proper soil mixture in a raised bed, this is a nice way to go. The cool thing about the raised bed method is that you can set it up on any surface, even concrete, which is what our soil seems like anyway. The amount of labor setting up a raised bed is almost certainly less than a in-ground Arizona garden, because pouring in your own perfect, spongy and rich soil from bags is definitely easier than having to break up and dig down into the Arizona's high-alkaline hardpan and caliche, fighting indestructable bermuda grass every step of the way. It might even be more cost effective in the long run than trying to improve the junky Arizona soil, especially when you consider the fact that you are getting higher crop yields.

I set up one raised bed in my backyard, and the radishes planted there are ginormous, much bigger than the ones in the field. I used the basic soil recipe from Square Foot Gardening, but I actually didn't have vermiculite (not being totally sure where to get any), so I just substituted top soil. So my mix was 1/3 organic compost, 1/3 peat moss, 1/3 top soil, all from bags from Home Depot. So far so good, the radishes I planted there are big, and the strawberries look real healthy.

Here is the website for the Square Foot method for further inspiration: www.squarefootgardening.com