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.