The Worm Bin Harvest

Table of Contents for this document:

Harvesting Vermiculture:

Harvesting Vermicastings (worm castings) and Worms:

Uses of Vermicastings:

WORM TEA from vermicastings or vermicompost:

WORM TEA from vermiculture -- direct:

SEEDS

DRYING the castings

HATCHING the worm cocoons

June 5, 2014 Edition

Once every three to four months the worm bin is ready for harvest.  The paper base in the bottom of the bin will be wet enough that it can’t absorb more water and the bottom of the vermiculture will start to get muddy.  To harvest the worm castings the vermiculture needs to be moist and crumbly – not muddy.

Harvesting Vermiculture:

Harvesting vermiculture without any screening -- to use as is -- does not require much work.  You simply divided the vermiculture from the worm bin in two and populate a new bin for yourself or to give away.

Harvesting Vermicastings (worm castings) and Worms:

I use a four mesh flat screen for the initial screening and an 8 or 10 mesh flat screen for the second screening.  First though, don’t even bother to try, if your vermiculture is too wet.  This is why I have emphasized maintaining the vermiculture at the right moisture level.  This is why I dump my bins and add dry newspaper to the bottom of the bin.  This is why I add dry newspaper strips to the top dressing and dry folded newspaper to the top.  The dry paper acts as a sponge to draw the water out of the vermiculture.  The goal is to have a moist, crumbly vermiculture to separate regardless of the separation technique.  At the right moisture the tiny castings do not stick together and are easy to work with.  When you do a separation you will end up with worms, worm castings and partially digested vermicompost, and stuff that won’t break down.  Worm cocoons end up with the worm castings and can be hatched in an additional process step.

Uses of Vermicastings: I use the worm castings as side dressing on plants, in the bottom of a furrow when planting, at 20% with potting soil when planting seedlings, or house plants.

WORM TEA from vermicastings or vermicompost:  I make aerated worm tea from the castings or compost.  Add one quart of castings or compost to 4 gallons of water in a 5 gallon pail.  Aerate with a fish tank bubbler for 12 hours; add one TBS molasses, aerate for another 12 hours, and use right away for best results.  I occasionally stir the tea with a paint stirrer powered by an electric drill to further aerate the tea.  Tea is a living culture of beneficial microbes and nutrients.

Uses of worm tea: My wife uses it to water house plants once a month and in the garden as a liquid fertilizer every two weeks.  She likes the convenience of the worm tea.

WORM TEA from vermiculture -- direct:  If you use vermiculture to make tea you can dump a quart of vermiculture,  worms and all, into 4 gallons of water and then strain out the worms and undigested material to put back in the bin – very quick and easy separation.  Then bubble the tea as above.

I like the convenience of making worm tea by this method.  I don’t have to spend time on the separation process.

The worms are used to repopulate the worm bin and to start new bins.

The undigested vermicompost goes back in the worm bin.  Eventually the worms and microbes eat or decompose nearly everything but some things take a lot longer than others.  For example the skin of an avocado may last a year -- the same for corn cobs.

SEEDS in the worm castings however either remain dormant and sprout in the garden or sprout in the bin.  Also carrot tops, beet tops and potatoes will often sprout and grow.

Keep weed seeds out of the worm bin.

Seeds that sprout while the castings are being stored can be screened out before use.  Storing the castings in cold storage for a few weeks can stratify the seeds and facilitate sprouting.  I have used this method to eliminate nearly all seeds from the castings.

DRYING the castings for long term storage requires the moisture be removed from the castings to the point that the microbes form spores (sporulate).  On a good drying day (sunshine, warm, low relative and some breeze) put the moist castings on a tarp in the driveway.  Turn them occasionally and when they are dry enough to slide off the tarp without sticking they are dry enough to store (estimate 5 to 6 hours).  Dry worm castings have a shelf life of at least three years.  In the winter the castings can be dried in a warm, dry room.  I use shallow cardboard boxes with a thin layer of castings spread over the bottom.  This process takes longer – 3 to 4 days.

HATCHING the worm cocoons that are collected with the castings requires another process step before you dry the castings.  (This is more work than most people are willing to undertake but it allows you to grow the size of your worm farm faster if that is your goal.)  I put the 4 mesh accepts from the first screening step into a bin with fresh food.  The food is put inside a mesh onion bag and buried in the castings.  After 10 days the mesh bag is removed and whatever worms have hatched and crawled inside the bag with the contents – worms and all – are removed and dumped into a worm bin.  This process is repeated until the mesh bag yields very few if any worms (2 to 3 months.)  The 4 mesh castings are now free of most of the cocoons that will hatch and can be screened through the 8 or 10 mesh screen to obtain the final product. The 8 or 10 mesh screen rejects go back into a worm bin for further digestion.  You will also recover some small worms in this final screening step.