OUTLINE OF HARVESTING PROCEDURE

TO OBTAIN WORM CASTINGS

FROM A WORM BIN

June 9, 2014 Edition

1 -- Open the worm bin and dig down to the base paper to assess if the moisture is too wet to screen.

If the bin is moist and the vermiculture crumbly then it can be screened -- proceed to step 2. If it is muddy and too wet to screen, add dry material and postpone the harvest for at least two weeks. Refer to post

How to Harvest a Soggy Wet Worm Bin?

2 -- Dump the worm bin into the large tote.

Use the rubber spatula and paint brush to clean most of the castings out of the worm bin into the large tote.

Use paint brush to clean the castings off the wooden base and put the base back into the worm bin.

3 -- measure out 2 pounds of dry folded newspaper and put it into the worm bin on top of the wooden base.  Overlap the sheets of newspaper to completely cover the wooden base.

The newspaper acts as a sponge that will soak up the excess moisture that works its way to the bottom of the bin.  In another 3 to 4 months the newspaper will be saturated with water and need to be replaced again.

4 -- now tear up the wet newspaper that is in the old base paper and set it aside in an empty tote.  This will be used as bedding if needed to bring the level in the worm bin up to the molded line on the side of the bin (about 4 inches down from the top lip of the bin.)

As we screen the vermiculture the rejects (rejects are what doesn’t pass through the screen) go back into the worm bin.  If there is sufficient volume of rejects to fill the worm bin to the molded line additional bedding isn’t needed.

5 -- now start the screening process using the 4 mesh sieve.  I screen the vermiculture right back into the large tote and put the rejects into the worm bin.

I screen the vermiculture several times (at least two times) through the 4 mesh sieve before trying to switch to the finer sieve (either an 8 mesh or 10 mesh).  The reason being that screening through the the 4 mesh sieve is quicker and after several passes nearly all the adult worms will be rejected and returned to the worm bin. Small worms and cocoons are not removed from the castings by the 4 mesh sieve.  The 10 mesh sieve removes many cocoons and nearly all of the small worms.  The 8 mesh is similar but not quite as efficient as the 10 mesh.

Note about sieves: The coarsest sieve is 4 mesh which means there are 4 openings per inch.  The two finer sieves are 8 mesh (8 openings per inch) and 10 mesh.  The 10 mesh is the finest sieve I use.  It screens out nearly everything but very small undigested material and some very small seeds (tomato for example).  The accepts of the 10 mesh sieve is nearly all worm castings.  The castings need to be pretty dry in order to screen them through the 10 mesh sieve.  I often will stockpile 4 mesh accepts and dry them some before I try to screen them through the 10 mesh sieve.

6 -- Storage and shelf life:

4 mesh accepts, not dried: This is best used right away.  Since it still has some worms, worm cocoons and compostable material, it is not “stable” enough for long term storage.  In the winter it can be stored as is in an outside shed and allowed to freeze.  Once the weather warms it needs to be used or processed further to stabilize it.  Don’t seal undried castings in an airtight container -- they will continue to “work” and go anaerobic after they use up the oxygen -- let them breath.

8 and 10 mesh castings, not dried: Best to use right away or store in a cold place -- same as the 4 mesh accepts.  These castings are more stable than the 4 mesh castings because more of the compostable material has been removed.  While the castings are damp they will mold and mildew.  I don’t believe this hurts the efficacy of the product but it doesn’t smell or look good when it molds.  Don’t seal in an airtight container -- it will continue to work and go anaerobic.

8 or 10 mesh castings, dried: Have a long shelf life -- 3 plus years.  If you don’t have immediate need for the castings then dry them and they will be ready to use when you need them.  You can store dried castings in an airtight container.  The microbes form spores and stay dormant until the moisture and temperature are right for them to start growing again.

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.

How to Harvest a Soggy Wet Worm Bin?

One of the most common concerns of willing worm workers using one of my worm bins  is that the vermicompost gets soggy wet.  When it comes time to harvest the bin by screening through a 4 mesh sieve the vermicompost is too wet to screen.

I am posting the follow email string between myself and one of my willing worm workers who had this concern and after following the posted instructions had a successful harvest.  I am posting this to share the instructions more broadly.

From Jim to me:

Hope all is well.

A quick worm question. My worm mixture is always quite wet, almost soggy, and seems excessively wet to me. Nevertheless, the worms are prospering. I try adding more newspaper on top, but that only helps some.

Otherwise, it's all proceeding fine.

My reply to Jim:

Hi Jim,

Good to hear from you -- thanks for the update.  And here is my not so quick answer to your quick question.

Wet, soggy worm bins are common but not recommended.  The bottom of the bin is probably full of water because the dry paper we put in to start has become saturated long ago.  Probably at about 3 to 4 months (June -- July) -- and needs to be replaced.  Don't dump your bin because the bottom will stink because it has gone anaerobic. Also, the leachate will saturate your worm castings leaving you a muddy mess.

Worms don't seem to mind when the worm bins get soggy wet unless they can't breathe.  They can't live in an anaerobic environment so eventually your worm bin will be too wet even for the worms and they will try to leave.  When that happens they will crawl out of the bin onto your floor.  Since you didn't mention this that means the bins haven't got to that point yet.

Here are a few suggestions on how to dry out and harvest your bins: 

Get yourself a bag of peat moss or something similar.  It needs to be dry and of plant origin -- many possibilities.  It needs to have the capacity to absorb lots of water.  I use compost from my compost pile that has been thoroughly dried out and screened through a 4 mesh sieve.

Set up outside a large bin capable of holding twice the capacity of one of your worm bins with room to spare.  I use a 23 gallon tote.  When you are done adding dry material to your vermiculture, you will have twice the volume you started with.

Put two gallons of dry material into the large bin and then add two gallons of your wet vermicompost to it.  (Dig the wet vermicompost out of your worm bin from the top.)  Mix the 4 gallons of material by hand -- I pick up large handfuls of the mixture and rub my hands together to do this mixing.  Once thoroughly mixed, do the squeeze test on the mixture to determine if the mixture is still too wet or too dry.  Correct the ratio of wet vermicompost to dry material based on the squeeze test and then repeat step one with new mix ratio and repeat until your worm bin is empty (down to the newspaper base.)

Now it is safe to dump your worm bin into another container -- it probably has standing water (leachate) in the bottom which will smell awful.  Get rid of it by dumping on your lawn or compost pile. Put the soaked newspaper base on your compost pile.  It can also be stored and used as new bedding.

In the large container you will now have more volume of vermicompost than will fit in your worm bin so you will need a second one temporarily.  

Now you need to put all the vermicompost back into your worms bins and wait 2 to 3 weeks for the worms to "turn" the mixture into worm castings.

If you have done this correctly this mixture will be ready to screen through a 4 mesh screen in about 3 weeks.  What is rejected from the 4 mesh screen will all fit back in one worm bin.

This is Jim’s reply after following the posted instructions above:

Just wanted to say I followed your instructions and had a splendid harvest this past weekend! All issues were solved, I've learned some things, and I'm starting anew. Thank you very much!!!

Wishing you and yours a bountiful and happy Thanksgiving!

Best Regards,

Jim 

Worm Bin Checklist to Hand Out to New Worm Bin Owners, Edited 2/22/13

Worm Bin Checklist to Hand Out to New Worm Bin Owners

Edited 2/22/13

Feeding:

Feed the worms scraps from the kitchen including fruit and vegetables, old bread, cereal and anything of plant origin.  This includes paper.  Tearing it up or chopping it up speeds the process but is not necessary.  Start with one pint buried in the front of the bin and then a second pint buried in back a few days later.  Check the front after a week and only add once most of the food is consumed (looks like dirt instead of garbage.) How soon you can feed again will depend on the temperature, the nature of the feed, the moisture, and number of worms.  One pound of worms should consume about ½ pound per week of garbage.  If you feed too much then the worms can’t keep up and the garbage may heat up and or decompose anaerobically (without oxygen -- which smells bad.)  Potato peels, orange peels, carrots, avocado skins, corn cobs take a long time to decompose but they will eventually disappear.  Softer foods disappear quickly.  Make your judgment when to feed next based on the softer foods.

Moisture control:

Not too dry, not too wet.  70% moisture is the target but the worms are tolerant of both wetter and drier conditions.  When there is too much moisture they may try to escape the bin.  You also run the risk of the bin going anaerobic (without oxygen) and getting smelly.  A wet bin at the bottom is to be avoided.  Add dry newspaper to help take up excess moisture.  If the vermiculture is too dry, spray water on top of the vermiculture to add water. Use “Squeeze Test” to measure.  Worms breathe through their skin which must be moist in order for them to breathe.

Squeeze Test to judge moisture:

Take a handful of the vermiculture or the wet newspaper and squeeze it as hard as you can.  If you can just see a little moisture coming out from between your fingers the moisture is perfect.  If you can wring water out of the vermiculture then it is too wet.  If no liquid moisture can be seen then it is too dry.

Temperature:

Not too hot, not too cold.  Ideal temperature is 68F for feeding and reproduction.  Worms will die if they freeze.  They will die if they get too hot – 90 to 95F is the upper limit.  If you keep them in an environment between 50 and 75F they will do OK.  In the summer they can be kept outside in the shade but need to be checked for overheating on very hot days.  Too much food all at once may decompose thermophilically and heat up the bin locally to 80F or 90F or more.  If this happens, the worms will move away to a cooler spot in the bin until things cool off and then they move back to eat the decomposed garbage.

Insect Control:

Use TAT Fly paper stuck to a folded sheet of newspaper in the top of bin to measure and trap the insects.  If an infestation occurs, cover the side vents with masking tape and put row cover over the top of bin held in place with nylon strap with elastic gusset to trap adults inside.  Fruit flies can’t pass through the screened vents but Fungus Gnats can.  The adult insects will eventually be trapped on the fly paper and the infestation will be controlled.

Edit: As of 5/04/12 I am no longer putting vents in the bins.  The top is covered with row cover to provide ventilation and improve insect control.  Row cover excludes and/or traps fungus gnats.  The screened vents do not.  The solid lid is used for convenience when transporting the bin but is removed and replaced with the row cover for use.

If the infestation is fruit flies, then adding the fruit fly trap too would be advantageous since it will actively attract the adult flies while the fly paper is just a passive trap.  Fungus gnats and shore flies are not attracted to the vinegar in the fruit fly trap.

Edit: As of 2/22/13: I am experimenting with an alternative method to hold the row cover on the bin.  I cut 8 two inch diameter holes in the lid of the tote bin for ventilation and then hold the row cover in place with the lid.  This reduces the ventilation and does not provide as tight a seal as the strap, however, it is more convenient to use than the nylon strap.  Time and experience will tell if this method is adequate for ventilation and insect control or needs further modification.  I am now providing the worm bin kits with this modification and am looking for feedback from users.  I am still providing the nylon strap too.

Harvest:

Harvest worm castings from the bin to use on house plants or in the garden.  They contain nutrients as well as natural plant growth hormones and disease fighting chemicals.  The use of worm casting up to 40% in plant soil has shown improved growth and harvest as well as more plant vigor and disease and pest resistance.  Make worm tea from castings as a convenient way to feed house plants.  Worm tea is just as good as the castings.

Edit: 2/22/13: I use a 4 mesh sieve for the initial screening of the vermiculture followed by a 10 mesh sieve.  The castings have to be dried some in order to go through the finer sieve.  If they are too wet they will ball up. The 10 mesh sieve removes nearly all the worms from the castings.  

Worm Tea:

This is made from worm castings.  Harvest the worm castings from the bin.  In a five gallon bucket put one pound of worm castings into 4 gallons of water.  Put a fish tank bubblier into the bucket to add air and stir the mixture occasionally.  (I use a paint stirrer on an electric drill but that isn't necessary.)  After 12 hours add 1 TBS of molasses and stir and bubble for another 12 hours. When done strain the mixture through a sieve into a watering can and apply the tea to house plants or to plants in the garden.  It can also be sprayed on the foliage.  It can be used as is or diluted 50:50 with water.  It will not burn plants.  This is a living culture and needs to be made fresh each time.

If you have insect pests in your bin ( i.e. fungus gnats) then using worm tea on house plants is preferable since the insects won’t be transferred to the house plants as they would be if you used the castings. (The castings contain the insect larva.  The tea does not provided you use a fine sieve.)

Q&A

How much food can I expect one bin to handle? 

One mature ten gallon tote has about 2 pounds of worms when it reaches maturity in about 4 to 5 months.  The worms will process about 1 ½ pounds per bin per week.  Starter bins that have one pound of worms to start consume about ½ pound per week.  These results vary with temperature, moisture, and the feed stock.

How long can I leave them without feeding?

Leaving them for a couple weeks is of no concern.  If you leave them for months without fresh food the worm population will gradually decrease and the worms will get smaller.  They will stop reproducing.  The worms will process everything in the bin over and over until there is nothing left but castings.  In a bin that I left for several months this way there were still a few small worms. 

Where is a good place to keep worms?

I keep mine in the cellar where it is about 65F year round.  A cellar that is at least 55F will work but the worms will not eat as quickly or reproduce as quickly if they were warmer.  Keeping them in your living space requires that you do a good job controlling insects.  Fruit flies, fungus gnats and shore flies are all nuisance insects that would like very much to have access to your worm bin for feeding, breeding and egg laying.

If you already compost what advantage is there to having a worm bin?

For one thing the convenience of having the worm bin in the house in the winter justifies it.  The worm bin can be used in the winter as a source of castings to make worm tea for house plants or seedlings.  My wife and I grow greens in the basement under a grow light in the winter for salads.  The worm castings and worm tea are used to feed these plants.  The worm castings produced by the worms during the winter are ready to be used to plant in the spring.  Also worm castings are superior to compost for seed germination, plant growth, vigor, disease and pest resistance and harvest.  Use up to 40% with potting soil or garden soil for best results.  Even as little as 5% produces measurable results.

Design and Construction of My Worm Bin, Original post 4/13/11, Edited 7/28/12

Design and Construction of My Worm Bin

Original Post 4/13/11

Last Edited 7/29/12

Materials and tools to construct:

Ten Gallon Sterilite plastic tote

Cheapest  1 inch X 3 inch strapping you can buy. One 8 ft piece is enough for one bin.  I use four pieces the short way on top cut 10 1/2 inches and two pieces cut 13 ¼ inches the long way underneath.  I use hot melt glue and screws to hold the base together.

Plastic Window screen material to cover the base

Hot melt glue to hold window screen to wooden base

One inch metal putty knife to spread hot melt glue

Heat gun to heat metal putty knife to facilitate spreading of hot melt glue

I cut a piece of window screen to cover the base and hold it in place with hot melt glue.  I heat the metal putty knife with the heat gun in order to spread the hot melt glue.

Row Cover to cover bin, I use All Purpose Fabric, from Gardener’s Supply Co. Item 32-646.  It comes in 6 ft by 20 ft  piece – enough for 24 bins.

One inch wide nylon strap material, 50 inches long, cut in half

One inch wide elastic strap material, 9 inches long, cut in half

Lots of old news paper, don’t use the glossy inserts

Construction:

Construct base to fit in the bottom of tote and cover with the fiberglass screen.  I use four pieces of strapping the short way on top and two pieces the long way underneath.  I use hot melt glue and screws to hold the base together.  I use Hot Melt Glue to hold the screen in place -- no tacks.

I cut a piece of cardboard by trial and error to fit the bottom of the bin and then use this as a template to mark the base to trim it to fit.  I use the same template to mark and cut the screen for the base.

Plug the holes near the handles with masking tape or
Gorilla Tape.  

Cut piece of row cover the size of the lid – use lid to draw outline on the row cover and then cut leaving four inches to spare all the way around.

Make belt from nylon strap and elastic: My wife makes these “belts” by cutting two pieces of the nylon strap 25 inches long and two pieces of elastic material 4 ½ inches long.  She sews the four pieces of material together with a slight overlap at the seams resulting in a belt that is 56 ¼ inches around when relaxed and stretches to 61 ½ inches when fitted around the top lip of the bin.  This tension provides the seal which keeps insects inside or those outside from getting in.  If the strap is too loose the seal is inadequate to keep insects in and if it is too tight it is very difficult to put the belt on the bin.

Why?

Ventilation and air circulation help reduce condensation inside the bin.  Getting rid of the moisture that is a byproduct of the vermiculture process is very important.  The vermiculture should stay moist and the castings should be crumbly – NOT muddy.  The air space under the base helps too. 

Worms need air to breath; they absorb oxygen through their skin.  And air promotes aerobic decomposition which is the “good” kind.  Anaerobic decomposition (without air) produces nasty smells.  The row cover provides more than enough ventilation.

Drain – I have eliminated the drain which came with the original bin.  It was there to drain off excess “tea” that accumulated in the space under the base.  The drain leaked.  Also I have changed my method of getting rid of the excess moisture which has eliminated the need for a drain.  

Base – The base is to support the bedding and allow excess moisture to accumulate below the bedding.  Otherwise the bottom of the bin would get soggy wet and so would the vermiculture in that area.  Wet muddy vermiculture is to be avoided.  There is less air in a wet environment and can result in anaerobic (lacking oxygen) decomposition which smells awful.  We want aerobic (in the presence of oxygen) decomposition.

Row Cover over top of bin and all holes plugged – to keep resident flies inside the bin until captured in the fly trap or on the Fly Paper and to exclude visiting  flies that are attracted by the smell of good food. These visitors would lay their eggs if given a chance.  With the fly trap and or Fly Paper installed inside the bin there will be few if any flies inside the bin under normal conditions.

I have 25 worm bins in my cellar covered as described and we don’t have a problem with flies in the cellar.  

My Worm Bin, Original post 4/13/11, Last Edited 2/22/15

My Worm Bin

Original Post 4/13/11

Last edited 7/29/12
Last edited 2/22/15

Ten gallon plastic tote from Wal-Mart, Sterilite Brand, cost about $5.

A wooden base in the bottom covered with window screening material provides air space under the bedding and a space to collect excess moisture.

I eliminated the drain – more on that later.

Several dry folded newspapers to act as a sponge to soak up excess moisture.

Shredded news paper strips that have been dampened make up the next layer.  This is the layer that the worms live in and in which you bury your food scraps.  It is also where the worm castings accumulate as the worms do their thing.

Dry shredded news paper strips on top of bedding to absorb excess moisture.

A layer of folded dry newspaper on top.

Screened vents in the top of the sides.

Edit: 7/29/12: I have eliminated the screened vents and instead use a piece of garden row cover to cover the top of the bin and hold it in place with a one inch wide nylon strap with an elastic piece sewn in.  The tension in the strap holds the row cover on tight. The row cover provides plenty of ventilation and does a better job of keeping flying insects out of the bin (or ones in the bin from flying out).  Particularly, this has solved a problem I had with fungus gnats infesting the bin.  The fungus gnats could access the bin through the screened vents.

I purchase the row cover from Gardener’s Supply Co. Item 32-646, All Purpose Fabric, 6ft X 20ft – enough for 24 worm bin covers.

Screened vents in the lid.

Edit: 7/29/12: The lid has been replaced with row cover.  I also lay a couple sheets of folded newspaper on top of the row cover to retard drying if the bin seems to be drying out.  

A baited Fly trap to capture fruit flies.

Edit: 7/29/12: If fruit flies are a problem then continue to use the baited fly trap.  I have had more trouble with fungus gnats and another small fly identified as a Minute Black Scavenger Fly which looks a lot like a fungus gnat.  They are not attracted to the vinegar bait in the fly trap.

New 7/29/12: A strip of TAT Fly Paper to trap flying insects inside the bin.

To trap flying insects inside the bin I use a strip of TAT Fly Paper unrolled from its container and stuck to a sheet of dry newspaper that is put in the top of the bin under the row cover.

Stick the bins if you stack them to allow ventilation.

Edits 2/22/15: 
I have eliminated the screened material on the top of the wooden base.  The newspaper on the top of the wooden base provides it own support.  I use 2 pounds of folded newspaper on top of the wooden base to absorb the excess moisture from the vermicompost.  I change the newspaper every 3 to 4 months when I harvest the worm bin.  I tear up the old wet base paper and use it as bedding when needed.

I keep the bin filled to within 3 to 4 inches of the top with moistened newspaper torn into strips (the bedding.)  The worms and microbes digest the bedding during the 3 to 4 months between harvests.  Adding bedding material helps keep the vermicompost from compacting and turning anaerobic.

I use a plastic storage bag or plastic shopping bag over the top of the vermicompost to help keep the top from drying out.  In the winter the air is very dry and the top of the bin will dry out unless evaporation is retarded.  The plastic works well.  In the summer when the humidity is higher the plastic cover has to be removed or reduced in area to prevent the vermicompost from getting too wet. 

Worm Bin Checklist to Hand Out to New Worm Bin Owners

Worm Bin Checklist to Hand Out to New Worm Bin Owners

Updated 12-20-2011

Feeding:

Feed the worms scraps from the kitchen including fruit and vegetables, old bread, cereal and anything of plant origin.  This includes paper.  Tearing it up or chopping it up speeds the process but is not necessary.  Start with one pint buried in the front of the bin and then a second pint buried in back a few days later.  Check the front after a week and only add once most of the food is consumed (looks like dirt instead of garbage.) How soon you can feed again will depend on the temperature, the nature of the feed, the moisture, and number of worms.  One pound of worms should consume about ½ pound per week of garbage.  If you feed too much then the worms can’t keep up and the garbage may heat up and or decompose anaerobically (without oxygen -- which smells bad.)  Potato peels, orange peels, carrots, avocado skins, corn cobs take a long time to decompose but they will eventually disappear.  Softer foods disappear quickly.  Make your judgment when to feed next based on the softer foods.

Moisture control:

Not too dry, not too wet.  70% moisture is the target but the worms are tolerant of both wetter and drier conditions.  When there is too much moisture they may try to escape the bin.  You also run the risk of the bin going anaerobic (without oxygen) and getting smelly.  A wet bin at the bottom is to be avoided.  Add dry newspaper to help take up excess moisture.  If the vermiculture is too dry, spray water on top of the vermiculture to add water. Use “Squeeze Test” to measure.  Worms breathe through their skin which must be moist in order for them to breathe.

Squeeze Test to judge moisture:

Take a handful of the vermiculture or the wet newspaper and squeeze it as hard as you can.  If you can just see a little moisture coming out from between your fingers the moisture is perfect.  If you can wring water out of the vermiculture then it is too wet.  If no liquid moisture can be seen then it is too dry.

Temperature:

Not too hot, not too cold.  Ideal temperature is 68F for feeding and reproduction.  Worms will die if they freeze.  They will die if they get too hot – 90 to 95F is the upper limit.  If you keep them in an environment between 50 and 75F they will do OK.  In the summer they can be kept outside in the shade but need to be checked for overheating on very hot days.  Too much food all at once may decompose thermophilically and heat up the bin locally to 80F or 90F or more.  If this happens, the worms will move away to a cooler spot in the bin until things cool off and then they move back to eat the decomposed garbage.

Insect Control:

Use TAT Fly paper stuck to a folded sheet of newspaper in the top of bin to measure and trap the insects.  If an infestation occurs, cover the side vents with masking tape and put row cover over the top of bin held in place with nylon strap with elastic gusset to trap adults inside.  Fruit flies can’t pass through the screened vents but Fungus Gnats can.  The adult insects will eventually be trapped on the fly paper and the infestation will be controlled.

If the infestation is fruit flies, then adding the fruit fly trap too would be advantageous since it will actively attract the adult flies while the fly paper is just a passive trap.  Fungus gnats and short flies are not attracted to the vinegar in the fruit fly trap.

Harvest:

Harvest worm castings from the bin to use on house plants or garden.  They contain nutrients as well as natural plant growth hormones and disease fighting chemicals.  The use of worm casting up to 40% in plant soil has shown improved growth and harvest as well as more plant vigor and disease and pest resistance.  Make worm tea from castings as a convenient way to feed house plants.  Worm tea is just as good as the castings.

Worm Tea:

This is made from worm castings.  Harvest the worm castings from the bin.  In a five gallon bucket put one pound of worm castings into 4 gallons of water.  Put a fish tank bubbler into the bucket to add air and stir the mixture occasionally.  (I use a paint stirrer on an electric drill but that isn’t necessary.)  After 12 hours add 1 TBS of molasses and stir and bubble for another 12 hours. When done strain the mixture through a sieve into a watering can and apply the tea to house plants or to plants in the garden.  It can also be sprayed on the foliage.  It can be used as is or diluted 50:50 with water.  It will not burn plants.  This is a living culture and needs to be made fresh each time.

If you have insect pests in your bin ( i.e. fungus gnats) then using worm tea on house plants is preferable since the insects won’t be transferred to the house plants as they would be if you used the castings. (The castings contain the insect larva.  The tea does not.)

Q&A

How much food can I expect one bin to handle? 

One mature ten gallon tote has about 2 pounds of worms when it reaches maturity in about 4 to 5 months.  The worms will process about 1 ½ pounds per bin per week.  Starter bins that have one pound of worms to start consume about ½ pound per week.  These results vary with temperature, moisture,  and the feedstock.

How long can I leave them without feeding?

Leaving them for a couple weeks is of no concern.  If you leave them for months without fresh food the worm population will gradually decrease and the worms will get smaller.  They will stop reproducing.  The worms will process everything in the bin over and over until there is nothing left but castings.  In a bin that I left for several months this way there were still a few small worms. 

Where is a good place to keep worms?

I keep mine in the cellar where it is about 65F year round.  A cellar that is at least 55F will work but the worms will not eat as quickly or reproduce as quickly if they were warmer.  Keeping them in your living space requires that you do a good job controlling insects.  Fruit flies, fungus gnats and short flies are all nuisance insects that would like very much to have access to your worm bin for feeding, breeding and egg laying.

If you already compost what advantage is there to having a worm bin?

For one thing the convenience of having the worm bin in the house in the winter justifies it.  The worm bin can be used in the winter as a source of castings to make worm tea for house plants or seedlings.  My wife and I grow greens in the basement under a grow light in the winter for salads.  The worm castings and worm tea are used to feed these plants.  The worm castings produced by the worms during the winter are ready to be used to plant in the spring.  Also worm castings are superior to compost for seed germination, plant growth, vigor, disease and pest resistance and harvest.  Use up to 40% with potting soil or garden soil for best results.  Even as little as 5% produces measureable results.