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Chooks and Worms in the Greenhouse

The following is part of the original, longer version of my article “Expert Advice for Greenhouse Growing”, published in the October/November 2007 issue of Mother Earth News.


The Integrated Greenhouse

Chickens in the Greenhouse

I was intrigued by the idea of keeping chickens in the greenhouse since seeing it in practice at Polyface Farm in the Shenandoah Valley (home of Joel Salatin, sustainable agriculture guru). Part of our Fall, 2005 greenhouse renovation referred to in “Greenhouse Basics” (replacing the foundation boards with block) involved installing some block partitions for chicken pens as well, with light wood framing and poultry wire on top. (Click on the thumbnail above for design and construction details.)

I had three reasons to overwinter chickens in the north end of the greenhouse. Plants take in carbon dioxide in order to harvest energy from its breakdown into carbon and oxygen, so the CO2 in the poultry’s exhalations should be of benefit to them. Now, before you think I’ve gone off my rocker factoring chicken breath into the greenhouse equation, know that in The Netherlands growers pay good Dutch money for bottled CO2 to pump into their greenhouses. Of course, there is no way I can measure how much difference my flock’s exhalations make, but the logic seems sound.


Greenhouse Pen

My second assumption is that the body heat of the enclosed flock will moderate the overnight chill in the greenhouse. Again, I have no control for testing this proposition scientifically, but I had 43 chickens, three ducks, and two African geese in there at the height of last winter—I’m convinced that more than 250 pounds of warm living bird has to make a difference.

Finally, I hate confining my flock in the winter. It’s a necessity, since they would degrade the dormant pasture sod if on it full time. (I make do with deep litter over an earth floor as the best alternative inside.)




Winter Yard

That is, it was a necessity, until it occurred to me I could heavily mulch the garden area outside the flock’s sleeping quarters in the greenhouse pens, net it with electronet fencing, and release the birds onto it during the day. (I used several 800-lb round bales of old hay, since a dry season did not permit a heavy fall cutting off my pasture.) The results were more than satisfactory: The mulch was deep enough (six to eight inches) to prevent freezing of the soil in my climate (Zone 6b), and the busy chickens stcratched down through it to live animal food (earthworms, slugs and slug eggs, etc.), and germinating seed in the hay—both a terrific boost in nutrition. The mulch absorbed the poops laid down and scratched in by the flock, rather than accumulating as a slick glaze on a patch of bare frozen dirt, eager to run to the nearest stream, lake, or estuary (to say nothing of the groundwater) with the first thaw. The mulch thus recaptured that manure as fertility for the soil in the coming season. The chickens, quite cold hardy if not wet, enjoyed themselves in the sun, on even the coldest days. And shelter at night, or from rain during the day, was always a few steps away inside the greenhouse pens.

By spring, the mulch hay had been shredded to something between fine mulch and finished compost, and was easy to apply in the garden, even between closely planted crops like carrots. (When you use a mulch like this, which contains pulverized droppings, it is advised that you allow 60 days—some would say as much as 120 days—before harvest. Frankly, I have not paid much attention to such “withdrawal times” when using homestead manure—an entirely different beast from manures of animals in high-confinement operations—and have never had the slightest problem with such mulches.) Finally, remember that the mulch was laid down over a garden, and was protective of its soil, preventing the horror of bare soil over winter.


Worm Bin


Lid Construction

Vermicomposting in the Greenhouse

I experimented with a 3x4-ft worm bin for several years. When I did the greenhouse renovation project, it seemed the perfect opportunity to step up to more serious vermicomposting. We put in two courses of 4-inch hollow block for the bins, dug almost 16 inches into the earth, 40 feet right down the center of the greenhouse. Every 8 feet, we put a cross wall of block, to give five 4x8-ft bins 16 inches deep. We put two 4x4-ft lids made of ¾-inch plywood on 2x4 framing over each bin, giving in effect two 4x4 sections in each bin. (Great for management: I can empty out one section and refill with bedding. The worms migrate in and populate from the full side.) When the flock is out of the greenhouse over the summer, their two 8x8 pens are used for an additional 128 sq ft of vermicomposting bin.


Bin Lids

Since I needed access down the center anyway, I didn’t lose much growing space to the new worm bins. And those substantial 4x4 lids over the bins have been a godsend. I routinely roll a fully loaded wheelbarrow over them. They are a great place to lay out work projects (the Lady of the Manor having forbidden doing so on the front porch since we re-decked it). We’ve even set up a table on them and had a picnic there; and I addressed a seated class of sixteen on them one raw March day.

Beginning the Cycle

Of course all the kitchen throw-offs that don’t go to the flock get fed to the worms. But the scale of my operation since the expansion is way beyond the “worms eat my garbage” scale. I haul in pony poop by the pickup load from a neighbor who breeds and boards horses. I find that pure horse manure usually doesn’t heat up enough to be a problem for the worms. Manure mixed with hay, straw, or sawdust will do so (as in a compost heap); but in the two-halves management I practice in the bins, the worms in the one side can back off and wait out a heating/outgassing spike in the new material before starting to nibble at the edges.

Harvesting Earthworms

The worms serve well the admirable goal of responsible manure management. In the process, they convert the manure bedding into castings (earthworm poop), one of the best of all natural fertilizers—rich not only in plant nutrients in forms easy for roots to take up, but carrying a huge load of microbes to boost the micro-life in the top inches of the soil. Last winter, the populations were finally high enough to make regular harvests of earthworms to feed the flock. To harvest, I simply shoveled out one or two five-gallon buckets of almost finished bedding at a time, and dumped it out on the mulched garden. The chickens and ducks made short work of the earthworms and worm eggs (the vegetarian geese were appalled), in the process scratching the castings into the mulch and “banking” their fertility against the coming withdrawals of spring. (Note that one should offer the bedding in a different part of the garden every day—otherwise excess, and harmful, fertility can build up in one spot.)

Feeding Worms