Sunday, December 23, 2012

winter composting in a cold climate

the new compost pile- still going
If you garden, and especially if you garden organically, you know the value of compost.

Making rich black garden soil from garbage is a feat that could be compared to alchemy.  You're taking what is virtually worthless and making it incredibly valuable.  At least that's how I see it.  That's how our backyard garden manages to be more productive each year, though we pull an awful lot of vegetables out of it.

Of course- we live in Minnesota, and one of the main climatic limiting factors when composting is the cold winter.  There are five months when the average low temperature is below freezing.  From November 4th to April 5th we, at least according to the averages established within the 1970-2010 time period, bottom out at or below 32F.

That makes this sort of garden alchemy much more difficult.  Essentially the process of composting is a process of controlled rot and putrification.  And when the conditions outdoors are similar to the inside of your freezer, rot and putrification take place very, very slowly.

But there are things that can be done to help the rotting continue to happen even during the cold upper midwestern winters.  I'll outline a few below.

One that the compost coordinator at our community garden does, is to mix fresh loads of greens (nitrogen-rich items that are typically fresh and moist) in with some browns (dried-out

the three-stage composter at our community garden
and carbon-rich items such as leaves or newspapers or dry grass) frequently. 

She's almost obsessive- in a good way- about making finished compost for the garden. She hauls in beer mash from a brewery- beer mash being the leftover barley from the malting process- and mixes it with dry leaves in the three stage composter in our community garden (see left).  It works too.  I was there to check out the garden today, and poked the compost a few times with a stick, and steam began rising from where I had poked it.  And it was about 15F at the time.  Not bad at all.

The process of mixing the browns and greens creates a favorable environment for the microscopic creatures that break down organic material.  (See a fantastic explanation of how, here, at Small Batch Garden).  I concern myself less with the how of the process than with the why- which is the fact that it works.   Given enough mass- typicially more than a cubic yard of it, and a balance of nitrogen-rich and carbon-rich materials, and a bit of moisture, the microorganisms get busy and heat the whole mess up, and make black gold much more quickly than would be possible under normal conditions.

I am less disciplined than the compost coordinator.  I simply pile whatever I have on hand into our backyard compost pile, and turn it once in a while when I think of it.  Yes, I do make an effort to balance browns and greens once in a while.  If I've dumped a lot of sticks and leaves in the pile, I go looking for some of my neighbor's grass clippings that he generously leaves near the back of his garage.  They're just the thing I need to get the pile heated up.  That, or some kitchen scraps.   A pile of apple peels works as well, or better than grass clippings.  Enough of those will get the compost really cookin'.

the current state of my community garden plot
Of course, in winter, cold is not the only limiting factor.  Moisture is also an issue.  I could put all the apple peels on top of the pile that I could find today, and they wouldn't do any good, because they'd freeze solid within a few minutes.  While we often think of winter as a cold season, it's also typically a very dry season in the upper midwest.  It snows, but an inch of snow is equal to a tenth of an inch or less of rain.  That, and snow tends to stay frozen for a while, doing a compost pile absolutely no good at all during that time.

So on a day like today, I look around for a supplemental moisture as well as a heat source.

My kids like taking baths, which I should be thankful for.  We've trained them not to drain the tub right away in the winter, instead letting the warmth and steam from the tub heat and humidify the house for a while.  Today, I let the water sit for an hour or two, warming the house, and also allowing some of the chlorine (which -yes- the city adds to the water even in winer) to evaporate , then brought two five-gallon buckets from the garage, and scooped up as much water from the tub as I could, and dumped them on the compost pile.  Then I went back and did it again.

It percolated right in, really quickly, which tells me that I still have a warm and porous compost mass going.  Feeling around the edges, I was able to get my fingers into it, and once I had gotten past the first inch or two, the pile was slightly warm.  Very nice!  It should be warmer tonight after two trips from the bathtub to the compost. 15 gallons of water at about 80F should do a lot to reinvigorate the little creatures doing their work in there.

Another source of moisture and warmth and nutrients that is a bit less socially acceptable (but it probably comes with the kids' bath water anyway) is pee.  Urea is one of the most nitrogen-rich things found in nature, with a carbon: nitrogen ratio that is more nitrogen than carbon.  Do a little research on C:N ratios and you'll realize how rare that is.

Of course, humans tend to eat a lot of salt, and that also ends up in our pee, so it is possible to have too much of a good thing, but in smaller, diluted doses, it's a fantastic fertilizer and microorganism stimulator for compost piles.  There have been times when I've been working outside, and have added a bit of organic liquid microoganism stimulant to the compost when nobody was looking.  And the compost thanked me for it.

It's funny to think that our modern synthetic nitrogen fertilizers- synthesized from fossil fuel (natural gas- also known as methane) in complex reactors, and sold as a controlled substance (because people have made bombs from the stuff) are really a synthetic form of pee.  It's slightly more complicated than that, but really, we go to all that expense and trouble to create a synthetic version of something we flush down the toilet every day.

And- think about this- before we flush it away- we mix it with two gallons of chlorinated, fluoridated drinking water, that we then pipe to a sewage plant several miles away, to separate out all of the component parts and dispose of them separately as toxic waste.

That's really a microcosm of what is wrong with Western society.  And we wonder why we're having problems?

rose hips and shadows on the winter solstice
I thought I'd leave you with a photo I took a couple of days ago on the winter solstice.  The world didn't end as predicted, so I am still here, and so are you, to enjoy all the winter holidays, Christmas being one of those.  I was walking into the house after taking a picture of the compost pile and was struck by the beauty of the rose bushes, almost bare except for the bright red rose hips, contrasting with the green canes and the severe shadows cast by the winter sun.   It was a subtle and unexpected study in green and red.

Those colors are all around on every possible thing this time of year.  By now they're kind of sickening on a sweater or in a store window, but truly beautiful when they take you by surprise in nature. 

I'll review my seed selections of 2012 next week.  Until then, a merry Christmas and happy Hannukah and fabulous Festivus to you.  

A happy winter solstice to all, and to all a good night. 


  1. I finally had a chance to read your latest and have to applaud you for not just talking about compost, but also pee!! Even among some organic gardeners I have known, pee seems to be off limits for some reason, I don't get it. It helps close a circle of fertility that so many gardens (even healthy thriving ones) need, and humans manufacture it everyday!! Bravo!

  2. Thanks Andy! It needs to said more times that pee is a fantastic fertilizer. Here in the US we are all to squeamish about talking about natural body functions, and I think pee as fertilizer is a casualty of that. I should add that I don't typically use it in the vegetable garden- I don't want to scare people off from eating at our place. But I use it a lot on ornamentals and in the compost. And it needs to be diluted. You can burn plants with it.

  3. This naturally leads to the topic of composting toilets! The idea of utilizing our bodily waste ( both liquid and solid) could literally change our landscape! Americans need to get over the phobia of hating the human body, and it starts with poop and pee. These bodily functions that all people share in common, could be the start of healing our depleted soil. Culturally and historically, people have composted and used human body waste successfully for thousands of years, we need to start using these wasted resources now!!

  4. I couldn't agree more. The difficulty comes from integrating them into our lives culturally. Pee disappears in the landscape pretty much instantly. Poop not so much. It's fragrant, flies like it, and so on. I lived for a summer on an organic farm that used a composting toilet and had a humanure pile. It was surprisingly fragrance and fly-free. I think the amount of sawdust had a lot to do with it. On one of my first few weeks at the farm, I was working on a project in the farmyard, and went to grab a handful of sawdust from what I thought was a compost pile, and ended up instead with a handful of sawdust plus a mysterious brown substance! I survived- and that was my introduction to the practical side of humanure production.
    Fitting a composting toilet and humanure pile into a small city lot may be more of a challenge than I am up to, though I have some ideas. We'll see if I am able to implement them.