Yesterday I harvested worm castings and fed my worms.  So, I thought I would share a little information on my vermicomposting experience and my system now.

When we first started vermicomposting in the suburbs, we set-up some nice, tidy plastic tubs with specially formulated layers of stuff that included purchased materials like vermiculite. We included a drain so we could catch the liquid runoff from the bin and use it as compost tea when we watered our plants. We used  a tarp to separate worms from castings and harvested quart jars of castings to sprinkle on our small garden. And it was wonderful.

But when we moved to our homestead and made our vegetable garden eight times larger than our back yard garden had been, we realized a quart of worm castings every few months wasn’t going to get us very far. We needed buckets and buckets of the stuff.  Also, we didn’t have much kitchen waste any more since most of it went to our chickens or pigs.  Initially, I thought of just using worm castings in the greenhouse. But, then one day I made an amazing discovery.

The area outside our goat shelter collects a lot of rain run off from the hill above. I started throwing down straw before rain to make it easy for me to get to the goats without slipping.  I also put a few pallets in that area so that goats wouldn’t need to walk in wet muck after rains. The goats loved the pallets and treated them as lounge chairs. And they started pooping like crazy on top of that straw. Then I’d add more straw, it would rain, they would poop.  I’d add more straw, it would rain, they would poop…

After a couple of months of this straw-rain-poop cycle, the few wheat seeds left in the straw started sprouting and growing at record rates. And the goats started grazing on the wheat. This concerned me because all goats have intestinal parasites. As long as they aren’t overloaded with them, then it’s not an issue.

But when goats poop, parasites come out. Then the parasites lay lots of eggs in goat grazing areas. Then the goats graze and swallow the parasites. The more parasites they swallow and the more likely they are to end up with parasite overload and become sick. So when I saw the goats grazing on this fast growing wheat in their heavy poop zone, I realized I had a parasite problem in the making.  I also realized that if wheat grew that fast even with goats grazing there, then that was awesome soil I should be using somewhere else.

I grabbed a wheelbarrow and started digging.  And that’s when I found that fabulous rich black gold, full of the highest densities of red wrigglers I had never seen. I ended up digging out about 18 inches of worm castings that had been made from nothing more than goat poop, straw, and rain water in just a few months.

And that’s when I threw out the suburban vermicomposting rule book and took our worm operation big time. I made a 4 x 8 foot bed using cinder blocks for the sides, landscape fabric for the bottom, and heavy re-purposed wood slat and wire mesh lid to keep out pests.

Worm Bed Inside

I gave those worms loads of goat poop and straw (no more than a 4″ layer to avoid risks of hot composting) plus all the no-nos from our kitchen, like onion scraps, meat, forgotten leftovers, uncrushed egg shells, as well as weeds, grass clippings, and leaves.  Through experimentation, I discovered that as long as whatever I put in there was intermixed with straw or leaves for loft and aeration, then the worms would break it down.  As for the eggshells, the worms crawl inside and eat all the goo and lining. When I harvest my castings, the shells are brittle and crumble with just a little squeeze.

I’ve made myself a few new rules for my system now.

  • I keep about 3-4 inches of straw or leaf cover on top of the bin to hold in moisture and discourage the worms from crawling out.
  • I harvest the castings and replenish the worm food about once a month so worms don’t have to live in too much of their own poop for too long.
  • I give them fresh food and a good watering when I harvest.
  • I throw in weeds with soil clumps still attached when feeding for grit and other biological goodies.
  • If we have a run of hot weather and no rain, I water the bed weekly too.
  • I keep my kitchen stuff in a buckets and age them for at least a week, so they are already partially decomposed (slimey), before I feed them to the worms.
  • I don’t layer the materials anymore, but I do break up clumps of heavy stuff with straw and leaves so worms can easily move through it.
  • If I include chicken poop, I age it for a couple of weeks and mix it in with other stuff.
  • I don’t give cat or dog poop to the worms because these are supposed to be taboo (though I suspect the worms would eat them).
  • I don’t open the bins unless it 55 degrees and sunny or 65 degrees if not sunny.

As for harvesting… I use two methods.  If I have good stuff to feed them like myceliated mushroom blocks, then I push all the old stuff to one side, load up the new stuff on the other side, and wait for a few days until the worms move over to the new pile.  Then I dig out the old stuff and spread everything remaining across the bed and cover with straw or leaves.

If I just have normal stuff that worms eat, but maybe don’t love, then I wait for a somewhat warm, sunny day.  I push back the straw and leaf cover and let the bed heat up.  The worms move down to the cooler, darker parts as the sun beats down, drying the upper layers. So, then I just dig out the stuff on top and leave the bottom few inches in place.  I add the new food and push the cover materials back in place.  I add more straw and leaves as necessary to keep at least a three to four inch pile on top.

Harvesting and feeding once a month takes about 15-20 minutes total.  The hardest part is that I made my lid really heavy to keep out critters, so it’s a bit strenuous to open and close.

Worm Bed

From about April to October, I get about a 5-gallon bucket of worm castings a month from this bed.  I add about 4-5 buckets of worm food stuff per month. I could probably get more but I’d have to work harder at it.  And 5 gallons a month is enough for our purposes.

In cooler months, I only get about half a bucket per month.  I don’t plant in cold weather, so this is enough.  And if we have a run of really cold weather, I’ll just wait two months to harvest.

After harvest, I don’t bother with sifting, unless I am using this for seed starting.  So what you see in the bucket below is what I put in the garden.  The undecomposed leaves and straw are remnants of the mulch covering and there are some of those eggshells to crumble.  Sometimes I add cardboard stuff, so occasionally I have to pick out bits of tape or the laminated coatings from some packaging. It’s always shiny and easy to locate. But otherwise, this stuff is pretty much pure poop.

Half bucket of worm castings

Our worm bed is dug into a hillside, so we get some thermal mass benefits from that to keep the worms warm in winter. I also heavy load the top layer of mulch materials in cold weather for added warmth. We have had single digit temperature nights, but they are rare. So far the worms have survived outside year round.  But I do hedge my bets and keep some in the greenhouse overwinter in case I need to replenish my outdoor population. (I’ll explain my worm bed system in the greenhouse in a future post.)

As for using the castings, mostly, I use them as soil cover for direct planted seeds.  I just lay out my seeds and cover with castings instead of pushing the seeds into the garden soil. Also, most plants like a boost after about a month of growing, so I’ll scatter a big handful around, but not on, the plant stems. For plants that have insect issues or are showings of stress, I’ll also give them a dose of worm castings.  I do sometimes use worm castings as a seed starting medium for transplants, but I generally prefer to trade seedlings up to worm castings than to start in them, or they get too spoiled from the outset.

Take it from a vermicomsting rule-breaker, you too can have great vermicompost with minimal labor on a useful scale if you have poop, weeds, straw or leaves, and kitchen inedibles. Wishing you and your garden loads of worm poop in the future!