September begins the busiest composting season. Through the autumn months, one of our compost bins fills to overflowing with discarded plant material from every part of the garden, while the contents of another bin are harvested.
It begins when the first chilly nights finish off already worn out potted annuals. These plants are dumped into an empty compost bin, their tightly woven root balls chopped to pieces with a sharp spade and then covered with a layer of finished compost from an adjacent bin.
It is an inaugural event. Over the next several weekends the pile grows with uprooted potato vines, the baked skins of winter squash and apple peels from a marathon soup weekend, mildew-covered summer squash plants, shriveled sweet pea vines, thick-stemmed sunflower stalks, the rest of the potted plants, overlooked cucumbers the size of footballs, worn out pole bean plants, retired tomato vines, and a legion of weeds.
Everything gets chopped with the spade as much as possible. Vegetable scraps from the kitchen get tossed in and, every so often, a few shovelfuls of finished compost or green grass clippings are added to fuel the fire with their high nitrogen content. The growing pile is soaked with water at the end of each day’s work.
By late September or early October, we’ve made one or two trips to the goat farm for composted goat manure. While most of these nannyberries are stockpiled under tarps for the winter (they are almost impossible to acquire in spring when they are actually needed), some are set aside to feed the host of composting bacteria. We bury materials thrown in the compost pile with nannyberries until they are completely covered, repeating the process layer after layer.
So the pile grows through October. A layer of garden debris, a layer of composted manure, another layer of garden debris, and so on. The contents of the kitchen compost bucket are tossed into the mix, as well. On cold October mornings, steam rises from the heart of the pile where bacteria are still hard at work.
We don’t bother to turn this autumn compost pile. At some point the fire goes out and the pile acquires a cap of ice and snow. If I wanted to keep those thermophilic bacteria working through winter in the center of the pile, a minimum size for the bin would be 5’ x 5’ x 5’ (ours are the more standard size, 4’x 4’x 4’) and, here in northern New England, I would still need to insulate the perimeter of the bin with straw bales or other suitable material. This sounds like a project for my retirement years!
We are careful not to toss dandelions, quackgrass, and other perennial weeds into the compost pile, nor any weedy plant that has gone to seed. The roots and stolons of perennial weeds, as well as many weed seeds, can survive the hottest compost pile temperatures to show up in the garden wherever the compost is spread.
On the other hand, we do not hesitate to compost the spent nasturtiums, calendulas, and other self-sowing annuals that we like to see pop up in the garden as volunteers year after year. By the time they are tossed on the pile, they’ve sown so many seeds through the garden that a few more surviving the composting process will not be noticed.
As one compost bins fills, the bin that contains finished compost empties as its contents are screened, then spread around the strawberry plants, highbush blueberry shrubs, and raspberry primocanes. If there is a surplus of finished compost, the grape vine and peach tree are next in line, followed by the garden’s trees and shrubs. We give priority to these permanent plantings because digging composted manure into the soil around them would destroy roots. The finished compost that we spread over the roots of these plants is quickly incorporated into the soil come spring.
Screening finished compost is always necessary. Corn cobs, orange rinds, and sunflower stems take forever to decompose, so anything too large to pass through the screen is recycled through the growing compost pile. A coconut half-shell spent three years in our compost piles before finally ending up as a bird feeder on the back porch.