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.