How to Clean and Use Your Finished Compost Everywhere
Book: Backyard Farming: Composting | Author: Kim Pezza | ISBN: 978-1-57826-587-9 | Hatherleigh Press, 2015
You did the work. You built the pile, turned it, waited, maybe even raised some worms. Now you’ve got this dark, crumbly, earthy-smelling stuff sitting in your bin. Congratulations, you made black gold. Chapter 8 of Pezza’s book covers how to clean it up and actually put it to use. This is the payoff chapter and honestly? It’s pretty satisfying to get here.
Cleaning Your Compost (aka Sifting)
“Cleaning” compost just means removing the stuff that didn’t fully break down. Seeds, sticks, lumps, random bits that need more time. You do this by sifting.
Not everyone sifts though. Some gardeners sift every batch. Some never bother. A lot of people land in the middle and only sift when the compost is going somewhere visible, like the top layer of a garden bed where you’ll actually see the chunks. If you’re tilling it into soil, those stragglers will just break down on their own eventually.
If you want to sift, you can make your own sifter pretty easily. Hardware cloth with half-inch wire mesh works well for a fine result. Chicken wire is coarser but still gets the job done. Even an old window screen set in a frame works for really fine sifting. Whatever you use, just shovel compost onto it and shake. The good stuff falls through. The rest goes back into the pile for another round.
Cleaning Vermicompost
Worm compost needs a different approach because you obviously don’t want to run your worms through a sifter. The goal is separating worms from finished compost without hurting them.
If you have stacking bins, this is almost automatic. Worms naturally migrate upward toward fresh food and bedding. Once they’ve moved up, just pull out the bottom tray. Done.
For non-stacking bins, push all the finished compost to one side. Add fresh bedding and food scraps to the empty side. Give the worms a week or two and they’ll migrate over to the new food on their own.
Then there’s the light method, which is genuinely clever. Dump your vermicompost onto a plastic sheet and shape it into about 9 small cone-shaped piles. Shine a bright light on them. Worms hate light and will burrow deeper into each pile to escape it. Scrape off the top layer of compost (now worm-free), wait a few minutes, and repeat. Keep going until you’re left with little heaps of worms at the bottom of each cone. Scoop them up and put them in fresh bedding. It takes some patience but it works really well.
If your worm population has exploded, start a second bin or give some away. Worm people are always looking for more worms. You could even sell them.
Using Your Finished Compost
One important rule before anything else: only use compost that is 100% finished. No recognizable food scraps, no half-broken-down materials. If you can still tell what something used to be, it’s not ready.
As Mulch
Spread a thin layer of compost over the surface of your soil. You don’t need to dig it in. Rain, settling, earthworms, and time will blend it into the soil naturally. This is the easiest application there is.
Lawn Dressing
Spread compost over your grass. Don’t rake it in. Don’t walk on it until it’s settled into the turf. That’s it. Your lawn will thank you.
Moisture Retention
Here’s a number that always surprises people: compost can hold up to 20 times its weight in moisture. For every 1% of compost you add to your soil, you get an extra 1.5 quarts of water held per cubic foot. If you’re in a dry area or dealing with sandy soil that drains too fast, compost is one of the best fixes you can use.
For Trees
When planting new trees, mix compost into the backfill soil. For trees that are already established, spread compost over the root area on the surface. But don’t pile it against the trunk. Compost sitting against the bark creates moisture buildup that leads to rot and invites insects. Keep a gap around the base.
Tilling Into Garden Beds
If you’re prepping a garden bed, spread compost across the surface before you till. It gets mixed in as you work the soil. Simple.
Container Gardening
Compost makes excellent potting soil. It holds moisture well while still draining properly, which is exactly what containers need. Mix it with perlite, vermiculite, or coarse sand for the best results. Pezza mentions she’s used straight compost in small pots with good results too. And don’t forget you can use compost tea for your container plants as well.
Herb and Vegetable Gardens
Herbs grown in compost-amended soil tend to be leafier and healthier overall. But here’s a useful detail for root vegetables and potatoes: mix compost into the soil a few months before planting, not right at planting time. Fresh compost has a lot of nitrogen, and too much nitrogen tells the plant to focus on growing leaves instead of roots. You’ll end up with huge bushy potato plants and tiny potatoes. Give the compost time to mellow in the soil first.
What’s Next
Your compost is clean and in the ground. But what happens when things go wrong? The next post covers troubleshooting common composting problems.