Most people who keep red wiggler compost worms do so for the nutrient-rich worm castings or vermicompost (worm poop) that is the end result of worm composting. We recently harvested one of our smaller worm bins, and took photos of the worm castings before using them in our garden.
Red Wiggler Worm Castings / Vermicompost in My Hand
Vermicompost is extremely fine-grained and almost silky feeling in your hands. This is because worm compost is made up of individual worm castings (pieces of worm poop), each of which is a bit bigger than a grain of sand. It’s amazing to look at a bucket full of red wiggler worm castings and realize that nearly every single piece has passed through a worm at least once! You certainly don’t recognize the original food scraps — with the occasional exception of pieces of eggshell, hard seeds, etc. that the red wiggler worms can’t digest.
Red Wiggler Worm Castings / Vermicompost
Many gardeners consider worm castings to be the “black gold” of compost because of this fine texture, and also the fact that vermicompost may have more nutrients than traditional or “hot” compost. A definite advantage is that each casting is surrounded by a thin mucous layer, which essentially makes them like tiny time-release nutrient capsules!
Red Wiggler Worm Castings / Vermicompost (with pumpkin seed)
The worm castings pictured have been “cured” using the process described in the excellent book
Recycle With Earthworms: The Red Wiggler Connection (by Shelley Grossman and Toby Weitzel). “Curing” vermicompost means letting it sit in a bucket for a couple of weeks after harvest, allowing any worms you missed while harvesting or newly-emerged babies to finish off any food which remains. The result is lighter, fluffier, and more completely broken down than “raw” worm castings. You definitely don’t need to cure your compost, but it’s a nice extra step if you have the time. People who saw our vermicompost at a Farmers Market last summer were amazed by the texture (we were, too!)
Red Wiggler Worm Castings / Vermicompost Closeup (with undigested pumpkin seed and piece of eggshell)
How to use your newly-created vermicompost? Worm castings are excellent as an extra nutrient boost added to gardens, for indoor plants, or anywhere else you’re growing. We used several gallons of worm castings as part of our seed starting mix this spring. We often see melon, cucumber, and even peach pits sprouting in our worm bins. I’ve heard (and believe) that worm castings may contain beneficial microbes which help prevent fungus from killing off newly-emerged seedlings.
Another use of worm castings to make “compost tea” or “worm tea”, a liquid mixture of worm castings and water that can be poured on your plants as fertilizer. Whether you choose to use it dry or as worm tea, your plants will thank you!
Happy worm farming (and vermicompost making)!
vermicomposting said,
July 7, 2009 @ 12:02 pm
Great pictures!
A couple of things:
1. I sent my castings in to get tested at a soil lab, and they came back relatively high in salts. So I would always use castings to amend soil, and not plant in it directly.
2. The seeds you see in the pictures are not killed by vermicomposting–the temperature simply doesn’t get that high. I’ve had seeds sprout in houseplants I added vermicompost to.
Thanks for the book recommendation, I’ll have to check it out!
Dan Moore
jaseroberts said,
July 7, 2009 @ 12:18 pm
Hi Dan, thanks for the comment.
1) As for salts in the worm castings, I would guess that it would tend to depend to a large extent on what you’re feeding to the compost worms. When I’ve added dinner scraps to my red wiggler worm bins, I’ve often thought that I’m probably adding way more salt than would be present in raw vegetables or other food prep scraps. At some point soon I plan to do some semi-scientific tests on plant germination and growth using various concentrations of worm castings / vermicompost vs. traditional “hot” compost and other soil blends.
2) I agree, composting with worms does not kill seeds like hot composting can (if done correctly). On the contrary, I think a worm bin provides pretty ideal conditions for seeds to sprout in. Fortunately, it’s generally only vegetable seeds that are mixed with the compost, no noxious weed seeds. When I sell worm castings, I screen them with a 1/8″ screen to exclude seeds and other bits. I thought they provided good size comparison in the photos, though.