Here up north we are still locked in winter. If you are growing onions from seed, this is the month to to start them under lights, but other than that we are still reading gardening books and dreaming of spring. So this month I'm going to talk about composting which is a useful topic any month of the year.
Compost isn't rocket science. It is just broken down organic matter. Nature does it every day. If you scrape away the top layer of leaves in the forest you will see nature's compost.
When people start gardening, they don't think of their soil as being alive, but it is. It is home to many organisms, both the good and the bad. My philosophy to gardening is to work with nature not against her. When you don't replenish the soil with organic matter (compost or turning under crops), you are effectively killing off all the good organisms that help your plants grow and some can even help protect your plants from disease.
When there is plenty of organic matter in the soil the good bacteria and fungi can thrive. Many of the good bacteria can hold onto excess nutrients in the soil and when they die they release them to the plants. Interestingly enough the good bacteria and fungi thrive in a compost pile. So when you add the organic matter, you aren't just making a good living environment for these organisms, but you are adding more of them to the garden.
You can get compost in several ways. You can buy it bagged up at the garden center, which can be expensive and isn't very sustainable. Many towns in my area now compost their leaves and grass clippings and it is often free for town residents for the taking. Some will even haul it to you in large quantities for a low price (fabulous for starting a new large garden). But you can't beat your own homemade compost. It costs exactly nothing and keeps a lot of kitchen waste out of the trash. When kitchen waste ends up at the dump it produces methane, one of the worst of the greenhouse gasses. So you are doing both your garden and the earth a favor by composting.
Where to put a compost pile
You want to put your compost pile on flat ground over dirt or grass. It needs to be within reach of your hose. It should be convenient to your kitchen and to your garden. You can put it directly in your garden and rotate it from year to year. The soil under the pile will be very fertile. Or you can put it in the shade which will help retain moisture in the pile.
How to contain the compost
There are many commercial compost makers, from the really expensive, like a tumbler, or the more inexpensive like a wire bin composter. Many people make their own. You can get wooden pallets and connect them to make a free composter.
Compost bins made from wooden pallets, photo copyright and courtesy of Our Engineered Garden
My solution is to buy wire fencing material. I measure out about 10' of it and cut it off. I connect the two ends and have a bin about three feet in diameter. Then there is the cheapest and easiest of all methods. You can just pile up the materials into a heap. Most people don't elect for this one since it takes up more space and looks messier.
To keep the compost hot you need a compost pile that is at least three feet in all directions. The mass of the pile will be able to insulate it well enough. If you want a smaller compost pile you need to go for one of the enclosed black plastic varieties (either a tumbler or the on ground ones) and keep it in the sun. There is an advantage to those types of composters. They keep animals from getting into them. I usually throw my kitchen scraps into one to keep the raccoons out of it. It has no bottom, but the top locks shut. If I lived in an area with rats, I might choose the tumbler kind that is totally encased for my kitchen scraps.
But what type of containment you use is totally up to how much you want to spend, the quantity you are making, and how you want it to look.
How to make a pile
I pile needs three things to compost well. It needs moisture, air, and orgainic matter to compost. Typically you can add any organic matter to your pile with certain exceptions. DON'T ADD:
|meat and bones||atrracts pests like rats to your yard (it can be done, but it is expert composting)|
|milk or oils||smell up the compost pile|
|dog and cat waste||contains parasites that can infect you|
|diseased plants||if the temps don't get high enough the disease can spread|
|toxic materials||dyed hair, treated wood, plants treated with herbicides or pesticides|
|black walnut tree||produces juglone which is toxic to certain plants|
The organisms that break down the organic matter in your pile like a 25:1 to a 30:1 ratio of carbon to nitrogen in the organic matter you put in. If you are really into getting the perfect ratio you can do a lot of calculations, but a good rule of thumb is to mix half green material (higher nitrogen material) and half brown material (higher carbon material). It might be called green material and brown material, but the color has nothing to do with it. And even the green material which is higher in nitrogen, still has more carbon than nitrogen.
|coffee grounds/tea bags||cardboard|
|green plants from the garden||dried plants from the garden|
It is best to cut up or shred the larger items. If you put a log into your compost it could take years to break down, but if the wood is chipped it will compost much faster since it has a larger surface area. Leaves, especially oak leaves, can mat down and take a while to compost, so shred them by running over them with your lawn mower. I've found that newspaper mats down very easily into a glue like substance. It is best to shred them and mix them with something else. Grass clippings also can mat down if left in large clumps.
Many people will tell you to make a compost pile by adding four inches of green material and then four inches of brown material. The reality is that they do better by being mixed up at the start. The pile heats better and things don't tend to clump as much when mixed. So add eight inches of mixed material together. To get the organisms you need into the pile to start it off faster add a shovelful of soil (I've done piles without any soil and it still works). Soil, especially good garden soil, will not only add organisms, but will add some minerals that might be lacking. You can buy compost activators from a store, but in reality all the organisms you need are in your soil.
If you add too much carbon to your mix, your compost will decompose more slowly. If your nitrogen is too high then you will get a smelly pile as the ammonia goes off. Your neighbors will not appreciate this. If you find you have done this, just turn the pile and add more carbon.
Without being moist the pile won't heat up properly. You want your pile to be moist but not wet. Think about the moisture content of a wrung out sponge. So as you layer your pile, water it so everything is just damp. If the pile gets too wet it will become anaerobic and the organisms that like to live in an airless environment will take over. These are not good organisms for your garden and they smell. If your compost is too wet, turn it to air it out a bit. I keep plastic over the top of my open bins to keep out the rain, since I live in a very rainy environment. This also keeps the rain from leeching out the nutrients in the pile. If I had sides to the pile this would probably be a bad idea since the pile needs to breath, but I don't. I just have wire mesh on the sides, which give it plenty of air.
My wire bins with plastic on top to keep out the rain
So you just keep adding to your pile until it reaches the top of your enclosure. In a normal household this can take a while and the bin is mostly populated with leaves and grass clippings and a few buckets of kitchen scraps. Some people collect things and make a big pile all at once which makes for better hotter compost, but doesn't fit the lifestyle of most people. If you want to collect things for you piles an easy source for carbon material is leaves in the fall, or newspaper from your friends all year long. Often tree companies will dump their chipped wood on you for a low cost or free (they have to pay to get rid of it). For nitrogen materials, coffee houses will often save buckets of them for you. I get pails of this from my husband's work. Grass clippings left by the curb are great if you know they don't use herbicides on them. You could probably even convince a nearby restaurant to save the kitchen scraps for you. I occasionally get these from my husband's work too, but there is someone with rabbits that works there that gets first dibs.
Maintaining a pile
Once you have your pile, you have two options. You can keep it turned every few days to a week to keep an active compost pile, or you can just let it sit like mother nature does.
For the active compost pile. The organisms in compost will heat up the pile if they get just what they want to survive. They need the right amounts of nutrients, water and air. Turning the pile adds air to the mix and will keep a pile hot if everything else is just right. After a few days to a week the temperature will start to come back down again. Now it is time to turn the pile. You keep doing this until the pile no longer heats up when you turn it. The better shredded your starting materials are the faster it will decompose. Also the closer to your 25:1 carbon to nitrogen ratio you have the better it will work. If things go well you can have compost in six weeks. The best compost for the garden is this kind of compost. When you add all your ingredients for your pile, you will notice that it heats up all on its own. It creates a whole lot of disease preventing fungi and in addition the nutrients haven't had time to leech out so it is more nutritious for your plants.
For the inactive compost pile you can just let it sit until it is ready. This can take up to a year. This method doesn't even require the right amount of nitrogen for the pile. If there is too much carbon it just takes longer to make. One type of compost is leaf mold, which is just made with a pile of leaves that have been moistened and allowed to sit. They have to sit for a year if very well shredded or two if not, but it is very low effort. This type of compost won't have the nitrogen content of a quicker compost. So on its ownit isn't a perfect fertilizer. It needs to be supplemented. It also won't supply the large quantities of beneficial organisms for compost tea (use actively made compost for that), but it will provide a lot of low work organic matter and your garden will love it.
If you just have compost pile that you constantly add little bits and never turn, the pile will never officially be done, but it will produce good compost at the bottom of the pile. Once a year you should dig off the top parts that aren't yet decomposed. At the bottom will be your finished compost. I do this with my black bin composter (shown above). The bin has little side slots from which they assume you will dig out your finished compost. They are way too small to do that. I just lift off the whole bin and move it over to a new spot. Then dig the unfinished bits back into the bin.
Using the compost
Compost is finished when it is dark and crumbly and smells like soil and not your original ingredients. Many people screen their compost before use. Sometime there will be parts that haven't decomposed, like a stem from a plant or a stick. Maybe some oak leaves have been resistant. These are usually screened out before adding to the garden. Screens can be bought or made from 1/2" hardware cloth. I don't usually screen mine. I go through it and pick out the larger bits and toss them into the next pile to form.
Once it is screened or sorted through you can dig it into the top six inches of the soil or use it as a mulch if you follow the no-dig philosopy. I tend to think of 1/2" as a minimum to add to the garden on a yearly basis to replace the organic matter that has disappeared over the year. I tend to add a lot more because I make a lot of compost and often use it as a mulch to keep down weeds. Most garden writers will tell you to add at least 1". With organic matter more is not a problem. It isn't like fertilizers. It won't burn your plants.
There is one other common way to use compost - in tea. Actively made compost and worm compost (which I'm not discussing here since I don't keep a worm bin and have no experience, but you can buy worm compost), are the best for compost tea. They both have a lot of beneficial organisms. The usual tea recipe requires a bubbler, molasses, rock dust and sometimes a host of other ingredients. The idea is that you give your good organisms a really good environment to grow and boost their population. I do not do this. I simply put the compost into a container and fill the container up with water. I let it sit a day; filter it; then spray it on my garden. The reason to do this is the organisms contained in the compost can out compete the disease causing ones on the plants. In addition it supplies some foliar feeding. The actively brewed tea works much better than my version, but requires equipment that I don't have. If you want to know how to do it, you can read about it in Fine Gardening.