Growing the Desert Garden

Welcome to the Desert Garden, with garden coach Tyler Storey, where we talk about everything having to do with gardening and landscaping in the Desert Southwest. From composting to Cercidium and agaves to arugula — we'll cover everything you want to know to grow your own beautiful Desert Garden.

Monday, November 3, 2008

From the Inbox: Composting Bins

From a Correspondent:

Is there a particular type of composter that works better in our environment? I have an irrigated yard.
Thank you.
MJ, Phoenix, Arizona

Good morning MJ,
As you may have noticed there are a lot of different composting bins for sale, and any number of plans available for building one yourself. Rather than making recommendations from among them, it's probably more practical if I give you some standards and characteristics that you can use when deciding.

  • Your ideal compost pile is about 3' x 3' x 3', a cubic yard. Any smaller and you may not achieve the mass needed for the process; any larger and you run the risk of anaerobic activity in the middle, and you may not be able to turn it. Five feet to a side is about the largest you'll want to go.
  • Be certain your bin has holes or vents for air circulation through the pile. Simple holes rather than adjustable vents are all that's needed.
  • The bin should have a lid to hold in moisture, though you can use a tarp if a lid is lacking, and the bottom should be open to allow drainage and prevent anaerobic decay.
  • The sun is intense in the Desert Garden, so look for a sun-resistant material; if you build it yourself, wood and wire works great.
  • Your compost bin should have easy access for turning the pile frequently; if it's hard to get to or too tall to reach down into, you're less likely to turn it as much as is needed. Many cities drill holes in used municipal waste containers and offer them as free or inexpensive composting bins. They have lids and are great but can be hard to reach into with your turning fork. With these, try removing the lid, turning them narrow end up, and setting the lid back on the new top; then, when it's time to turn the pile simply lift the can up and off the pile, set it to one side, and then turn the pile contents back into the bin.
  • I recommend you avoid rotating composters, but if you just can't resist, get one that spins on the long axis rather than end over end, and has inside baffles to turn the compost. The pickle-barrel composters that flip end over end are almost impossible to turn once the material is inside, and tend to produce large clumps of gooey smelly stuff.
  • Don’t get a composting bin that is intended to make "compost tea." This is the desert and our soils need organic humus material, not weak brown fertilizer. Also, with our warm climate the potential for pathogen growth in the tea far outweighs any supposed benefits.
  • Avoid bells and whistles – compost is a very simple process that in nature occurs under a tree in the forest; there's no benefit to paying for the fancy stuff.

In short: a simple bin of about a cubic yard that admits air, holds moisture, and is easy to get into.

Because you have an irrigated yard, you’ll want to place the composter in an area where it won't be in standing water, for even the shortest time. If your compost sits in the flood plain, you will generally end up with an anaerobic mess at the bottom of the pile.

I hope this helps,

Tyler

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