Making Green Living Logical

Building a worm bin is actually very easy to do.  A few basic supplies are needed: a pair of plastic bins (nesting) and one lid, some fiberglass window screen (steel will rust quickly), some composted (or fresh, if available) manure or compost mix (bagged is fine, organic if available), plenty of newspaper, a drill, a ¼ - ½ inch drill bit, a scissors, and a paper shredder (optional).

1. First, drill several holes in the bottom of ONE of the bins (this will be the upper bin, the one that contains the worms and materials).  Be sure to make holes in the lowest parts of the bin (many have raised areas inside), as the holes are there to allow excess water to escape into the lower bin.

2. Drill some holes in the lid.  This will allow airflow in the bin (oxygen is essential!).

3. Cut a piece of the window screen

to line the bottom of the upper bin

(this will prevent worms and materials

from falling into the lower bin).

4. Select paper.  DO NOT use newspaper with colored inks.  Colored inks can contain heavy metals, so only use pages with black-and-white printing on them.  Shred the paper in a paper shredder, or tear into small pieces.

5. Nest the upper bin (the one with the holes in it) into the lower bin.  The lower bin will catch excess water, and this “worm tea” is actually a very potent fertilizer on its own.

6. Put a layer of the shredded paper in the bottom of the upper bin, on top of the screen.

7. Add the manure.  Use your judgment; the microbes and mold (and the worms) will do better feeding on fresh materials, so completely composted material (or potting soil) is not ideal bedding on its own.

8. Add as much shredded paper as you can.  Don’t pack the bin full, or there won’t be any room for food scraps or worms!  It is remarkable, though, just how much paper will fit into the bin once it’s moistened and mixed in.

9. Mix the bedding materials well.  Add water if necessary.  When

moisture levels are correct, you should be able to squeeze a handful

of the bedding and have droplets of water appear between your fingers.

If the bedding becomes too wet, add more paper to help soak it up.

10. Add food scraps and mix them into the bedding.  Best items are vegetable scraps (uncooked, not cold from the refrigerator, perhaps left in a plastic bag for a day or two to allow for decay to begin; nothing really acidic), fruit scraps (citrus should not be added), eggshells (but NO eggs!), and breads (sparingly, as they don’t contain much nutrition…they will, however, make a wonderful home for molds and get a bin going more quickly).  Basically, if you would ordinarily save it for your outdoor bin, you can put it in the worm bin.  Potatoes are great when starting up a new bin; leave small pieces, moistened, in a plastic bag on the counter for a few days and they will mold up nicely.  Keep out pet wastes (except rabbit pellets), meats, and dairy products, as well as oils, fats and salt.

11. Place the lid on the bin.

It is a good idea to allow the bin to mature for a few days to a

week before adding the worms.  This allows for a buildup of

mold and a microbial community, which in turn will allow the

worms to fare better right away.  The bin should be kept in a

warm location (the kitchen is perfect, the garage is way too

cold during the winter!).  The ideal temperature range for the

bin location is 59-77°F, with faster worm growth occurring at

warmer temperatures.  Do not allow the bin to get too warm,

as this can damage the worms.  They will tolerate a

temperature range of about 40-85°F, but these temperature

extremes will stress the worms.  Too cold and they will go

dormant or die.  Too warm and the bin will dry out quickly or

develop a smell, and the worms will begin to die off.

Building a Worm Bin

New material can be added every few days.  Keep scraps in a bag on the kitchen counter, not in the refrigerator (unless it will be a very long time before they are added).  Be careful not to overload the bin with scraps, as this can sometimes overwhelm the system and create a small odor, as well as attract fruit flies.  Do be sure to cover any added materials with bedding before closing the bin.

Keep the lid on the bin.  Worms live in the darkness, and too much light is not good for them.  Make sure, too, to keep the bedding properly moist.  A too-dry bin will result in too-dry worms, and they will not survive if allowed to dry out.  Too much water is not good either though, as the worms breath through their skin and require oxygen from the air to stay alive.  If the bedding seems too wet, add more shredded paper and mix it in well.

The worms used in vermicomposting are not the same as the night crawlers or “earthworms” found in bait shops or cruising through the garden soil.  While these worms consume soil microbes, they do not fare well in a compost pile.  The most common type of worm used in vermicomposting is the Red Wiggler.  Red wigglers are commonly found in outdoor compost piles (those that are on the ground anyway) and in manure (horse, rabbit, cow, and other herbivores).  They feed on the microbes, molds, and partially composted organic matter in the material.  These worms can be found quite easily in the aforementioned locations, or else purchased at stores that supply reptile food (crickets, mealworms, etc.).  They can also be ordered online in larger quantities (most reptile shops sell them in containers of around 50-100 worms).  The worms reproduce quickly under the right conditions, and their population will stabilize to match the food supply available.  To increase the ability of the worms to reproduce, calcium-rich materials can be added to the bin.  Well-rinsed eggshells are a great way to add this calcium.

A word about the fertilizer produced: once the bin is “complete”, meaning the material is knobbly in texture (these are the castings, or worm droppings), it is time to harvest the fertilizer and add fresh bedding.  Removing the castings is very straightforward; simply remove the upper layers of material (it should be mostly castings, as the worms will come to the surface to release their droppings).  Bedding that is added should be mixed into remaining bedding well, and care should be taken to pull as many worms as possible from the castings.  Remoisten to the proper level and recover.  The castings can be used like any fertilizer; spread around flowers, vegetables and trees and water.  Due to the high nitrogen content in the castings, care must be taken not to pile them up on the stems or trunks, as this could cause burning.  The “worm tea”, the water taken from the lower bin, is even more potent than the castings, and should be diluted 20:1 water (20 parts water to one part tea) before being used on plants.

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