Jay Gould, Master Gardener Volunteer Trainee

What’s a trommel? Websters defines a trommel as: a usually cylindrical or conical revolving screen used especially for screening or sizing rock, ore, or coal.

So, why does a gardener need one? Does your compost look like this? Such beautiful particles that plant roots can’t wait to penetrate and suck out the stored nutrients.

The common measure of “finished” compost has a uniform appearance with no identifiable plant pieces, no leaves, orange peels, etc. Well, not everything in my compost pile decomposes at the same rate. The coffee grounds and salad leftovers disappear in weeks, but the banana peels don’t.

So when the pile no longer heats up after turning and the top layer does contain a fair portion of composted material, I “process” the pile in my trommel. The “Raw” compost looks like this:

Filling a bucket of the “raw” compost and dumping in the upper end of the cylinder, all the fine material falls through the ¼” hardware cloth screen as the drum is turned.

In the last four feet of the cylinder, the hardware cloth mesh is ½” so the larger particles fall through and only the very large, un-composted materials exits at the bottom end.

With two minutes of rotation, a five-gallon mixture of raw compost produces a fluffy, rich treasure suitable for top-dressing and even seed starting.

Where do you get such a fabulous device? Well, you could order one on Amazon, of course. They are often used by gold prospectors, but a resourceful DIY-er can build one for under $100.

Mine consists of discarded, bent bicycle rims, skateboard wheels, rollerblade wheels, weight bench frame, left-over 2X4, used bike chain and a thrift store bike. The most expensive component is the hardware cloth – no cheap alternative. Admittedly, the first several versions required a very gentle touch to operate, but now I can process two dozen five-gallon bucks in an hour.

Oh, you can also process the free mulch provided by many municipalities and the result is a great substitute for the non-sustainable peat moss that many soil-less potting/raised bed formulations call for.

P.S. If you are really motivated, you can add a stationary bicycle, remove the front wheel, extend the chain, and rotate the drum while sitting/riding in comfort!

Now that’s gardening!

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