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Worm-Composting
WORM COMPOSTING
What? Worm composting is the easiest way to recycle food
wastes: Allow the worms to do all the work with no pile
turning, no smell, and fast compost production.
Why? Compost with worms to avoid the needless disposal of
vegetative food wastes and to enjoy the benefits of a
high quality compost product for your houseplants and
gardens.
Where? You can compost in many different containers, so long as
they are about the right size for your household (more
below). So long as the bin doesn't freeze, it can be
kept anywhere that is convenient. (At our office, we
even keep worm bins in file cabinets where they are easy
to access yet out of the way!) Other people keep their
bins in the kitchen, the workroom, or the basement.
How? All you need to do is find the proper bin, fill it with
worms and bedding, and then regularly bury your food
wastes. Cover the bin and the worms will do the rest.
When? Unlike other forms of composting, you can compost with
worms all year round. Why not plan your worm bin now?
The Proper Bin: A worm composting bin should be shallow and wide
instead of narrow and deep to allow you to bury your food in many
different places. Ideally, a bin should be about 8 to 12 inches
deep. How large your bin should be depends on how much vegetative
food waste your household produces.
A one- or two-person household will need about four square
feet of area to bury food in, and a three- to six-person household
might need six square feet or more. If you want to be more exact
in choosing the size of your worm box, the general rule is to allow
one square foot of surface area for each pound of vegetative food
wastes produced per week. (Of course, you can also use more than
one small bin.)
Now that you have figured out how large your box should be,
you will undoubtedly find many containers to be suitable for your
bin. Metal washtubs, plastic utility boxes, and wooden boxes are
all good containers for worm composting.
Many people construct their own boxes using exterior grade
plywood (exterior grade protects against rotting). If you prefer,
you may also buy bins exclusively designed for worm composting.
(See the reference section.)
The Proper Bedding: Now that you have chosen your bin, you need to
fill it with a bedding in which the worms will live and in which
you will bury your food wastes. This bedding is generally paper
based and will eventually be converted into compost along with the
buried food waste.
Shredded corrugated cardboard or shredded computer paper is an
ideal medium and hand shredded newspaper also works well. Inks on
these papers are generally carbon-based and the worms will happily
eat them along with the paper bedding.
Getting Your Worms: In order for your worm composting to be a
successful venture, you have to be sure that you are using redworms
(Eisenia foetida). Redworms reproduce quickly, don't mind being
bothered too much, and process large amounts of organic material.
These worms will move through the compost bin, eating the compost
and keeping it full of oxygen. This movement prevents the smelly
conditions that can arise when compost is not aerated.
Other worms, such as nightcrawlers, need more room in which to
thrive, or cannot live in conditions where they are constantly
being bothered. The easiest way to be sure that you are receiving
the correct worms is to buy them from a worm farm or bait shop. In
the reference section of this fact sheet are several listings for
worm farms that will mail worms to you directly at good prices.
Again, how many worms you need depends entirely on how much
waste you produce. One good thing, though, is that worms will
multiply or die off according to how much waste you bury.
Therefore, even if you don't have the perfect amount of worms at
the beginning, after several months the worm population will adjust
to the proper size. However, it is good to try to get fairly close
to the correct number of worms to start with: too few worms might
cause an odor problem and too many worms would be a waste of money.
The general rule of buying worms is buy one pounds of worms
for every three to four pounds of garbage to be buried each week.
(If the worms are sold by the number, there are about 1000 worms in
a pound.) For a one- or two-person household, this will probably
be 1-1« pounds of worms; for a three- to six-person household, 2-2«
pounds.
Setting up Your Box: Now you have your bin, your bedding, and your
worms, and are ready to get started. First, fill your bin with dry
bedding. Now add enough water so that all the bedding is wet, but
not so that puddles form at the bottom of the bin. The bin should
always be at this level of intermediate moisture. (Again, if you
want to be scientific, add three pints of water for every pound of
bedding. To make a hospitable environment for the worms, the
bedding should always have roughly a 75% moisture content.
Later, if you notice your bedding getting too dry, try
spraying it lightly to re-moisten. If you are using a plastic bin,
you may find your bedding getting too moist; please call a RISWMC
staff person at 831-4440 to discuss special management techniques
for plastic bins.)
Add one or two handfuls of soil along with the bedding.
(Often, the soil the worms are packaged in is enough.) Continue to
add bedding and water until you have about eight inches of wet but
fluffed up bedding in your bin. Now you are ready to add the
worms. Spread the worms out on top of your bin as best you can and
leave the room lights on for a few minutes. The worms, not liking
the light, will move down into the bedding. Cover the bedding with
a loose fitting cover or a layer of plastic and your worm bin is
ready to process your food wastes.
Burying Your Food Wastes: It is a good idea to bury your food
wastes daily, so no smell can build up in your compost collection
container. Cycle your wastes around the box so you are always
burying next to where you buried the day previously, but so that
every part of the box gets waste buried in it. The worms will
follow the waste around the compost bin and keep it aerated and
odor free.
Worms will eat any vegetable waste you produce within your
household. It is generally not a good idea to bury meat products
because they cause odor and may attract mice and rats. Excessively
oily foods, such as large quantities of oil or mayonnaise are also
not good foods to bury. With these small exclusions, basically
anything goes. You can bury potato peels, tea bags, coffee grounds
and filters, pasta, potato salad, spoiled foods, banana peels, etc.
So long as you are burying vegetable waste, the only thing
that you can do wrong is to bury too much waste in the worm bin.
If you do this, the food will sit around uneaten and build up a
smell. As stated earlier, eventually the worms will multiply and
eat this extra food, but the interim might be unpleasant!
Removing the Finished Compost Product: Within four to six months,
most of the paper bedding and the food wastes will have been
converted into a finished compost product, which is uniformly dark
and soil-like. You are now ready to remove the compost and use it
in your yard, garden, or houseplants.
There are several ways to remove the compost product. The
first way is to move the material to one side of the bin, and then
add fresh bedding to the empty side. Begin feeding the worms on
the empty side only, and within a month or so they will migrate
over. At this point, you may remove the compost. Then fill the
empty side with fresh compost. This is a very clean and easy way
to harvest compost, the drawback being that you lose a few worms.
Another way to harvest your compost requires sorting. If you
dump your compost into a pile, you can sort out worms into one pile
and your finished compost into another. This process can be made
easier by using a very bright light. The worms, averse to the
light, will move down into the compost giving you a worm-free layer
of compost to harvest on top. You can continue this process until
you have nothing but worms and a little bit of compost left in your
original pile. You might also want to divide the larger pile up
into several small piles; shine the light on one pile at a time,
brushing the compost off as the worms travel down to the bottom of
each pile.
Some people just like to use what is in their bin as compost,
worms and all, and start fresh with new worms. The drawback to
this approach is of course the cost of buying new redworms every
six months or so.
Which ever method you choose to harvest and use your compost
product, you will find it to be a rich and valuable soil additive.
Compatibility with Outside Composting: Some people like to put
their food scraps into an outside composting bin during the warmer
months, and use worm composting only during the winter. You can
maintain your worm bin minimally over the summer by feeding the
worms just a little (although the population will decline), and
then slowly start up again in the fall (gradually building the
population again).
Auxiliary Bin: After trying vermicomposting for awhile, you may
decide to set up another bin that is maintained minimally (by
feeding less often) and then used in times of increased food waste
generation, such as for holidays, parties, house guests, or
canning. You can keep your main bin in a convenient place, such as
the kitchen, and store the auxiliary bin out of the way until it is
needed.
Best Temperature: Don't put your worm bin outside! Although they
can survive in temperatures ranging from 50 to 80 degrees F, worms
process food most rapidly at household temperatures. Also, if
placed outside, other critters could disturb them. There are some
techniques for keeping your worm bin outside, but they require
special care; if you are interested in trying this consult Worms
Eat My Garbage for instructions.
Vacations: You can leave your worms for up to two weeks, but if
you go away longer, you may want to "board" your worms. Who knows,
you could convert your friends or neighbors to vermicomposting!
Also, when leaving home during cold months, make sure that the
house doesn't get colder than about 50 degrees F.
Fruit Flies: The only problem you are likely to encounter with
your worm bin is a fruit-fly infestation--especially in the warmer
months. To prevent this from occurring, add food gradually and
bury within the pile. Take immediate action if you spot fruit
flies; they are voracious reproducers, and if there are one or two
at first, there will soon be many more! Cut a piece of foam so
that it fits the dimensions of your box. Place it over your
bedding. The friut flies will not be able to fly up (and out) and
will fall back into the bedding and die.
Another weapon against fruit flies is a package of parasitic
nematodes. These are microscopic insects that enter fruit-fly
larvae and release bacteria which will kill the larvae within a few
days.
Nematodes are harmless to worms, and will only attack insects that
spend at least part of their lives in or on the surface of soil.
We have found the Hb strain of parasitic nematodes to be very
effective. They are shipped immersed in a small sponge which is
soaked in warm water and then applied to your worm bedding. (Fresh
bedding may be required to absorb the extra moisture.) A package
of 5 million is generally effective for a standard-sized worm bin.
Please see Reference section for where to buy nematodes.
REFERENCE
Ordering Worms:
Beaver River Associates, Josh Nelson, P.O. Box 94, West Kingston,
RI 02892, 401-782-8747; Worms are $28/2 lbs., $10 each additional
lb. Also sells pre-made wooden bins (see below).
Cape Cod Worm Farm, 30 Center Ave., Buzzards Bay, MA 02532, 508-
759-5664; Maggie and Lamar Pipkins; $14/lb. of worms (2,000);
company does not fill orders when ground is frozen (approximately
from Christmas to mid-March), but does develop a priority list for
fulfillment based on first-come, first-served, so order early to
receive shipment soon after thaw.
Commonwealth Wormery, P.O. Box N122, Westport, MA 02790, 508-636-
8981 (evenings); make checks payable to Wendy Henderson; $10/1b. of
worms, includes shipping; expect shipment within 1-4 weeks.
Many gardening-supply catalogues offer redworms for sale by mail.
Pre-made Bins:
Beaver River Associates, Josh Nelson, 401-782-8747 (address above).
Sells a well-designed wooden bin with convenient cover for $35;
sized for family of 3-4 (24x18x12"); $55 for bin with two pounds of
worms and instructions if picked up in W. Kingston, or $65 if
shipped.
Set Point, Chick Renfrew, 31 Oxford Road, Mansfield, MA 02048, 508-
339-9300. Offers plastic bins designed by Mary Appelhof in a
variety of sizes. Worms Eat My Garbage offered with bin.
Check gardening and environmental specialty catalogues for pre-made
bins.
Parasitic Nematodes (to control fruit flies):
Gardens Alive! 5100 Schenley Place, Lawrenceburg, IN 47025, 812-
537-8650. A mail-order catalog which specializes in organic
gardening products. We've used the Hb strain of nematodes, but the
names sometimes change, so consult with a customer-service person.
Prices (1993-94): Pkg. of 5 million: $12.50; pkg. of 10 million:
$18.95.
More Information:
Worms Eat My Garbage by Mary Appelhof: The definitive text on worm
composting. A must-read if you are serious about composting with
worms. Find a copy at a library or bookstore or order by sending
$8.95 + $1.50 shipping to Flowerfield Enterprises, 10332 Shaver
Road, Kalamazoo MI 49002; (616) 327-0108. ALSO, RISWMC offers
short-term loans to Rhode Islanders; call 401-831-4440 for details.
Worms Eat Our Garbage: Classroom Activities for a Better
Environment: For grades 4-8+ $19.95 + $2 shipping, available
directly from Flowerfield Enterprises.
Rhode Island Solid Waste Management Corporation: (401) 831-4440.
Will provide various plans (Mary Appelhof's designs) for
constructing wooden worm boxes; offers Worms Eat My Garbage;
experienced vermi-composters can answer specific questions about
worm composting; will provide limited quantities of shredded office
paper for bedding.
U.R.I. Gardening Hotline: 1-800-448-1011. Will answer specific
questions about worm composting.
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