Composting in the Fall

Many people more or less give up on their gardens by the end of summer. They are tired of weeding and watering and have picked all the fresh produce that they wanted. Now it's time to get ready for fall and winter holidays, maybe go on one last family trip, put the lawn furniture away, and settle down into a less active schedule.

But, now is the perfect time to get ready for next year and build up your stock of compost. Early fall is my favorite time for composting. For one thing, it is less hot, less humid, and there are fewer flying insects. But mostly because nature gives us the PERFECT blend of composting materials; dry grass, fresh grass, and fallen leaves. 

I have an older DR Lawn Vacuum/mulcher, it is about 15 years old now and is still going strong. There are many other companies that make pull-behind equipment as well as smaller units you push by hand. But, you can also use a regular lawn mower and just discharge the cut leaves and grass in the same direction and then rake up the rows of material. A mower won't chop it up as finely, but it works just fine and that is how I did it for many years.

I have two adjoining properties with a total of just over four acres, minus the footprint of the two houses. I also have many deciduous and conifer trees on the property that produce plenty of leaves and pine needles. That produces WAY more material than I could ever compost and use so I only run my mower and vacuum over the areas with the heaviest accumulations of leaves. You can see different layers in my DR Vacuum that show I mowed over areas with more and less leaves on the ground. 

It's the leaves that I really want, but they have to be mixed with other "brown" (carbon) material and "green" (nitrogen) material in order for the composting process to be efficient. Why are leaves important? Your tree's roots grow to wherever the nutrients and moisture are found. Down through the top soil and into the underlying base earth. What this layer lacks in soluble nutrients it makes up for in vital minerals and trace elements that the tree needs. These elements are usually leached out of the top soil, filtering down into the lower layers. The tree's massive root system extends down into these lower layers and absorbs the minerals and trace elements it needs to grow. They are transported up into the tree and are used in the annual growth spurt the tree does every spring and summer. Much of those minerals and trace elements end up in the leaves. When the leaves drop in the fall, all that mineral goodness is now laying on top of the ground, and you can "harvest" that.

Two years ago I went from a four-bin composting setup to a three-bin system. I miss that fourth bin. But a three-bin layout still works pretty good. One bin strictly holds finished compost where it "seasons" or ages and nutrients stabilize. It still breaks down a little bit through earthworm and insect activity, but bacterial decomposition has more or less stopped. That is the compost you can safely add to your garden and flower beds. A second bin is where I start the composting process by throwing in rough material without much regard for layering or establishing a green and brown ratio. It is sort of just a holding bin, but decomposition still occurs during the warm days of summer. I compost everything; weeds, sawdust, kitchen scraps, animal carcasses from the fall and winter hunting seasons, everything goes in the bin. This year, the bin to the right of the one showing below was the raw materials bin. To the left is the finished compost bin (it is fully covered to prevent nutrient leaching from rains).

In the fall, I mow and vacuum up a full trailer of leaves, grass, and pine needles (about 48-54 cubic feet). Then I start transferring rough material from the right bin to the center bin. I shake it and break it up so the material gets spread out in the new bin, which also aerates it. Oxygen is vital to good composting. I put down a layer 6-8 inches, and then add a layer from my lawn vacuum of 6-8 inches. I alternate layers of old, partially decomposed material with freshly gathered material. This transfers active microbes, worms, and other carbon digesting insects to the new material. It jump starts the composting process.

 

Old and new, old and new layers

 

 

 

This year, I lucked out and was able to get a large, free bag of coffee grounds from a local Starbucks. Most Starbucks will have a bin somewhere in their store (or you might have to ask) where you can get free bags of grounds. Coffee grounds are a rich source of nitrogen and will greatly accelerate the composting process. The micro-organisms also react to caffeine the same way that we do...a huge boost in energy! I spread a heavy sprinkling of coffee grounds on each layer of new material.

Using the old and new material I filled my bin to the top, over 70 cubic feet of space.

Four days later, after 24 hours of steady rain, the compost had settled down about 12-14 inches into the bin, just from its own weight and some initial decomposition. In the center of the bin I inserted a long-probe thermometer to check on how well the composting process was coming along.

Success! Outside air temperature is 51 degrees (F), inside temp is 143 degrees (F)! That heat, if you don't already know, is generated by the metabolic activity of the bacteria feeding on the composting material. This is considered "Hot Composting", which will kill most weed seeds and undesirable bacteria, making the resulting compost safe to use in food producing gardens. This pile will stay at that temperature for a couple days, it might even get a bit hotter, and then it will slowly cool down  due to a lack of oxygen in the pile. I will use a pitch fork to move all this material from the center bin to the right hand bin in mid-November to reintroduce fresh oxygen into the material and it will heat up a second time as the bacteria flourish again. Then the pile will cool down and go dormant during the cold winter days. But in the Spring, I will reap about 20 cubic feet of finished compost for my gardens.

22 October 2023 UPDATE: I had planned to turn my compost to remix and aerate it but before I did that effort I stuck the thermometer deep into the pile again and it was still 140 degrees F. So, I decided that is was doing just fine as it was and I would check it the following week and see how it is progressing.

5 November 2023 UPDATE: The core temperature was 70 degrees while the air temperature was 52. I decided to move the compost from one bin to another to aerate and mix the material. There was some half composted material in the bottom of the second bin so I forked that onto a trailer and my intent was to mix this old, cold material into the mix. As I dug out the new material just starting to compost, I made sure to completely break up any clumps by bouncing it on the pitchfork or by twisting the fork rapidly. This created very loose, airy material, which I spread out in the new bin. I layered in some of the old compost as I went. This looser mix, all fluffed up, filled the bin to the top. I checked the temp three hours after I was done moving everything into the new bin and it was just over 60 degrees.

10 November 2023 UPDATE: The compost core temperature was 152 degrees this morning with overnight air temps of 30 degrees. That is a hot pile. Fresh oxygen, and perhaps the introduction of some partially composted material, really kicked the biological activity into high gear.