Hi! You know me. Or, you should. I’m your compost heap. I’m the source of all that ‘black gold’ gardeners are always talking about. I sit out here behind the garden, day in, day out just hoping you will bring me more digestible goodies that I can make over into a rich delectable additive to put on your garden or lawn.

You may think I’ve got it easy – just sitting out here, basking in the sun. You may even think you’re the one doing all the work. After all, you do haul all those nice treats out to me. Don’t think I don’t appreciate those vegetable scraps, rotten left over salad bits and juicy green grass clippings. I really thank you and do a good job on those garden cuttings and plant prunings. And I love the way you mulch them up for me and mix them with straw or shredded newspaper and a bit of composted manure. And, of course, I really love it when you give me those periodic massages by turning me over every so often. You sprinkle on a little water to keep me from drying out, and I’m your friend for life. So, I can see how you think I’m just one pampered pile of mulch, relaxing out here, soaking up the rays while I enjoy the fruits of your labor.

But hey, while you’re over there weeding that plump little turnip on a hot summer day, or sitting indoors by that warm fireplace on a cold snowy evening, I’m hard at work out here. Compost doesn’t just happen, you know! You may add all the ingredients, but I’m the one who works the magic. And, believe me, it’s a full time job, 24/7 as they say. Oh, I may look calm and composed (get it?) on the outside, but inside I’m a seething cauldron of activity. Let me explain.

The real action begins when you’ve finished putting me together. It’s then that all the bacteria and fungi come together for a feast. First, while I’m still cool come a group of bacteria called psychrophiles. These critters love it when my temperature is low – between 55° and 70° F. Some can live and munch on carbon products (the brown material) down to freezing before becoming dormant. These guys are opportunists. As they eat whatever carbon they find, they produce heat. But the critters also need oxygen and nitrogen to live. That’s why you need to aerate me with a little stack in the middle or use an open sided bin so the air can get in to me. The green goodies and the manure give the nitrogen some fungi and bacteria love to eat. Now I start to warm up.

At about 70°F a new class of critters takes over the process. They really like temperatures between 70° and 90°F. Now the real banquet begins. They eat so much so fast that I really start cooking. This group is called mesophiles. They’ll eat anything. As they eat, they reproduce; the bacteria replicate, and the fungi produce little microscopic bulbs that hold spores. These bulbs erupt and spread the fungus throughout the heap. It travels in the moisture you sprinkle on me. It may not be a pleasant thought, but this digestion, is what keeps me alive and going.

The mesophiles turn me on. All that tough cellulose and woody lignin in the plant waste is now being burned. At 100° the mesophiles go dormant; some species die. But now the true heat lovers take over. These are called thermophiles (thermo=heat, phil=love). Temperatures from 90° to 200°F are nothing for this crew. Stick your hand down under my surface when they’re active, and you’ll get burned. Hey, some of these fungi are the same guys that thrive in those hot springs and geysers. They’ve got intimidating names like Chaetomium thermophile and Humicola insolens. But they’re nice guys. They finish off those tough cell walls and woody materials and break down the proteins and complex by-products left by their predecessors. As my temperature gets to about 150°, those pesky weed seeds and nasty fungal spores you threw on me die. They won’t be alive to pop up in your garden next year. Hey! Treat me right, and I’ll look out for you!

When all the food is gone, the thermophiles start to die off. I start to cool down. The mesophiles wake up and feast on the leftovers. As they finish up the goodies, I really cool down. Now the big guys come out. You’ve seen them, the earthworms and millipedes. Maybe you’ve even seen a large class of fungus working near my surface. Pull back my top covering and there’s a lot of threadlike, fibrous growth. These are actinomicetes (sounds like: act-in-o-MY-seats). They’re what give me that rich earthy smell that you like. They also help by producing enzymes that break down any woody cellular material that remains.

As you can see, I’m like a busy construction foreman. Think you’ve got troubles? There are several billion critters in every gram of me!! I have to organize and coordinate this entire workforce to make you a happy gardener. And I’ve got to keep them happy so they don’t go on strike and quit working.

But, I won’t let you down. When you see steam coming off me, you know I’m burning for you, baby!

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