Trench Composting
Garden waste is a natural bi-product of early spring garden preparation - but why send all that good organic material to the curb when you can compost it in you garden beds?
Spring is a time for planting - but it is also a time for garden bed preparation. This can mean hoeing, raking, tilling, adding soil and/or soil amendments, and it also means weeding. Some weeds are there from the previous year, and some may have started in April or May - but they all need to be pulled. This is a chore, and it is tedious, but when combined with trench composting, it is a great way to improve a garden bed and save money on soil.
What is trench composting?
Trench composting is simply the act of burying stuff that will compost. Many people make compost in compost bins, but with trench composting - every garden bed is a potential compost bin. This is where the trench comes in: everything gets buried, and eventually, it all breaks down.
How is it done?
A trench is dug, often the length of the garden bed, that will be deep enough to have at least 6 inches of soil on top of all the material that will be composted. I usually go 12” deep or more. Then, everything than can be found that will compost - including weeds - goes in the trench.
Next, you trample everything down, then add a layer of soil, then trample that down, and then finally fill it all back in and smooth out the soil to have the bed ready from planting.
What are the benefits?
Trench composting can bring the soil level of a bed up an inch or more depending on how much material is added to the trench. It is also a great way to make all that garden waste disappear. Finally, and especially in the case of pulled weeds, all the soil that is attached to the weeds tends to be fairly rich soil due to the fact that weeds, like all plants, have “root exudates” (organic compounds like sugars that are secreted into the soil), which enhance the soil quality and attract soil organisms. All of that goes in the trench and eventually, through the activity of soil organisms, improves the soil in the bed.
Will the weeds grow?
Some weeds (e.g. Japanese knotweed, coltsfoot, and goutweed) are remarkably tenacious and will find a way back up to the surface despite having been buried six inches deep or more, but most weeds cant punch their way through that much soil. If you are unsure, put all your weeds in water for a few days and let them drown before trench composting (warning - they will smell like death if you leave them too long); or, spread them out on a tarp in full sun for a few days before burying (same idea, just less smelly). If you are unsure of anything - don’t bury it!
What if animals dig it up?
Having animals find compost and dig it up is always a risk - but generally speaking, the deeper the stuff is buried, the less likely that is to happen. Honestly, I can’t recall the last time I had this problem.
How long does it take for everything to break down?
With the exception of logs and other things that break down slowly, most types of plant matter break down in a matter of months depending on temperature, moisture levels, and depth. With that having been said - it really doesn’t matter because this is something you tend to do only once a year - so by the following spring it will all be gone.
Final thoughts
Burying stuff. It’s the oldest trick in the book for getting rid of something you don’t want. In many cases - figuratively, psychologically, and even practically - this is a bad idea, but when it comes to trench composting, it’s a great idea! Don’t like weeding? Need closure? This spring, bury your garden waste and forget it was ever there.
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