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plumiebear

Heated worm bin

plumiebear
14 years ago

Let me start with the credits:

http://forums.gardenweb.com/forums/load/verm/msg0413312414926.html

http://www.redwormcomposting.com/winter-composting/winter-worm-bin-heating-a-novel-and-festive-approach/

These articles/instructions started me thinking about this bin. I don't really *need* a heated bin in my climate. I wanted to see if warmer bin temps really make much difference to the worms. Will they process food more quickly and will they reproduce more quickly? The main practical goal for this bin is to raise additional worms to help populate a larger flow through in 2-3 mos. I will not harvest the vermicompost. The entire contents will be dumped into my next flow through.

I started with a typical storage container: 18"x13"x16" (~15 gal.) I drilled a series of 3/4" holes about 1" from the bottom.

I sprinkled a thin layer of coir, added a sheet of cardboard & backfilled with more coir. The purpose of these is to soak up leachate.

Next is a layer of rock with most of an 18 ft. rope light coiled on top. I also routed the rope light through 2 holes near the top of the bin. Although I've not had problems with wandering worms, I figured I'd use the extra rope length as a light deterrent for any worms that might consider exploring. I then add more rock to partly cover the rope light and cover the vent holes. I think the density of these rocks will block most of the air flow. Kelly's instructions specified packing foam, which would have provided more air flow. I don't want to risk melting those, so I used rocks. Larger rocks would have been better, but this is what I had on hand.

I tested the rope light for an hour. The air temp inside the empty bin went from 60 to 69F. The rope light was warm, but I could comfortably hold it in my hand.

I lined the bin above the false floor with weed block cloth and put a layer of manure compost (a gallons worth) at the bottom. This is dense enough to block the light and has decayed to the point where the worms probably won't be interested in it. On top of this I put a gallons worth of pre-rot mush, then I dug up my in-garden worm trench and put in a final gallon of material (worms & compost). There may be too much food in there for the small squirm, so I'll probably need to add worms later. Lastly, I put a thick layer of damp leaves.

Here are the temperature readings (F) for the first few hours the light was on.

6 pm: compost 55, air 58

8 pm: compost 62, air 59

11 pm: compost 75, air 60

I didn't want to risk keeping the light on through the night. Slightly surprisingly, the readings at 8 am this morning were: compost 77, air 56. I guess heat from decomposition kept things going. I checked a few random spots and the range was 65-75. Later today I will set a timer to turn the rope light on 7pm-1am and then again 3am-8am. I'll see how that works.

Andrew

Comments (23)

  • marauder01
    14 years ago
    last modified: 9 years ago

    Very nice article Andrew.

    It will be interesting to see how it progresses. I suspect that the material closest to the rope light may get way to hot for worms to be near (ie local hotspots), but I guees you're only going to run it for a few months.

    Is the rock you put down going to work it's way through the flow through bin later as well? You must have some mean old "Clint Eastwood" kind of worms there "I eat barbed wire and p**s napalm" lol!

    Cheers and nice work

  • mendopete
    14 years ago
    last modified: 9 years ago

    Nice job and good post Andrew. I am north of you near the coast and my inground bin is always warmer (+10-20F or more) than the air temp except on those RARE hot days. The squirm love it right now! I would cover the bed with thick damp cardboard to block the top light and keep things moist. Tell us more about your wormtrench. Good luck and keep us updated. Pete

  • plumiebear
    Original Author
    14 years ago
    last modified: 9 years ago

    Thanks, gentlemen.

    marauder: I decided to see what would happen if I left the light on overnight. The temps this morning ranged from 75-95F. I dug around and found the worms active. They easily avoided the hot spots.

    I'm sure these worms are tough, but I'll leave the rocks out of the next bin. The worms can't really get to the rocks right now since the compost zone is lined with the weed block cloth. When it's time to transfer the contents of this bin to the flow through, I should be able to remove the bottom few gallons of material by grabbing the edges of the cloth and lifting the entire "bag" up. That would leave just the rock false floor with the rope light at the bottom.

    mendopete: You're so fortunate to have the space and manure for your large outdoor wormery. Those of us with smaller systems and non-manure food scraps have to work hard to keep bin temps 10F above air temps.

    Good idea about the wet cardboard. I was thinking of using a damp t-shirt, but the worms love cardboard.

    My worm trench is only 6 ft. long x 10" wide x 8" deep. I threw in food scraps on the bottom before adding a layer of compost with worms on top. I covered it all with a layer of leaves. I used "wild" red worms harvested from my regular compost bin. I was going to grow veggies around this trench. The idea was the veggie roots would benefit from the activity in the trench. Unfortunately my seedlings were gobbled up by various garden critters, so I decided to harvest the worms from the trench to start this new bin.

    Andrew

  • Katxena
    14 years ago
    last modified: 9 years ago

    I wonder if the rocks are acting like a heat sink, increasing the effectiveness of the rope light?

  • plumiebear
    Original Author
    14 years ago
    last modified: 9 years ago

    katxena, I think you may be right. It makes sense the rock would absorb heat while the light is on and then release the heat later. I wish I could say I thought of that when I used rock instead of foam peanuts.

    Andrew

  • singleton165
    14 years ago
    last modified: 9 years ago

    I would think that the rocks might make the light rope more economical, if you had it on a timer.

  • plumiebear
    Original Author
    14 years ago
    last modified: 9 years ago

    singleton165, I do have it on a timer. I have it set to turn on 8pm-midnight and 3am-7am. The bin gets a couple of hours morning sun and 3 hrs. afternoon sun.

    Andrew

  • singleton165
    14 years ago
    last modified: 9 years ago

    Andrew, sorry if I missed that. I was just noting that I think the rocks serve a valid purpose. I envy your climate...my bin is in the kitchen, and even then the temp inside usually hovers below 70 (just in the kitchen, the wood stove keeps the rest of the house cozy).

    Hmmm...since I'm done using the Christmas lights, I'm considering putting one of those strings in my bin to *hopefully* make things happen a little faster...I just might have finished compost for the garden in the spring after all.
    Great post and thanks for the idea!
    Tara

  • plumiebear
    Original Author
    14 years ago
    last modified: 9 years ago

    No worries, Tara. I had to check to see if I *did* remember to mention the timer in my original post. :-)

    Just as an update, today was overcast & "cool" and the bin stayed in the 70-75F range with the mild sunlight it received. I haven't fed the bin again, but I think these kind of temps will encourage microbial action when I do feed. That in turn should add even more heat to hopefully get temps close to the "ideal" 80F.

    Andrew

  • grower54
    14 years ago
    last modified: 9 years ago

    Singleton. I took a 30 bulb set of christmas lights with the medium size bulbs and cut in half lengthwise leaving 15 bulbs.I taped each end of the power cord (the end I cut) seperatley then taped them together. I put a hole in the side of my bin big enough to slide the bulbs through then pulled the whole string through. I started out using 4 bulbs(unscrewing the other 11 bulbs just till they went out) but it got too hot (90)so I unscrewed one until the bulb went out and am now maintaing a very constant 75 degrees. I have a 2x4 at each end of the bottom bin to lift the working bin up a ways and put some scrap hardi plank siding (cement product) on the floor of the bottom bin with the lights laying directly on it. When I started my second bin I repeated the hole in the side and the 2x4 and hardi plank, pulled about 4 bulbs through to that bin and it is now staying around 75 also with 3 bulbs screwed in.For the wire between the two bins I took the bulb out and taped it up well so it wouldn't get wet.I do have the string pluged into a gfci strip so as to not fry the little ones and as I don't have any lechate I'm not concerned with moisture in the bottom bin. The whole cost was about $6 for the string of lights. Steve

  • Shaul
    14 years ago
    last modified: 9 years ago

    I too,use rope light and also found the problem of the lights getting too hot. I solved it by installing a dimmer switch between the lights and the power source. Now I have full control of the wattage output (and heating), from low to high.

    Shaul

  • plumiebear
    Original Author
    14 years ago
    last modified: 9 years ago

    Steve: that sounds like a great use for old Christmas lights. I see lots of people freecycling these after "upgrading" to LED lights.

    Shaul: my rope light is only rated at 37 watts and can be held in my hand indefinitely even after being on for a few hours.

    Andrew

  • Shaul
    14 years ago
    last modified: 9 years ago

    Hi Andrew;
    The problem is that my rope light is rated at 16w/meter. I have 5-meters, that's 80w. Try holding a (lit) 80w light bulb in your hand..., and in a small space it just puts out too much heat. That's why I installed the dimmer switch.

    Shaul

  • sparkett788
    14 years ago
    last modified: 9 years ago

    I have an indoor worm bin,but put it in an unheated laundry room--so I used an aquarium heater set in a gallon jug of water. Worms all gather around it--it's preset at 78 degrees, and submersible. But it does dry out around the water jug and then the worms move elsewhere. I like the rope light idea better. I think the aquarium heater in water would work great in an outdoor enviroment. Either seal the unit or check the water level regularly.

  • Shaul
    14 years ago
    last modified: 9 years ago
  • plumiebear
    Original Author
    14 years ago
    last modified: 9 years ago

    More options (link below):

    Andrew

  • leearnold
    14 years ago
    last modified: 9 years ago

    If I may, I have another suggestion - They sell (and I use) grow mats for starting seedlings. The have a preset temp of around 70*. If you set your bin on top of one of these, it should stay within that range.

  • plumiebear
    Original Author
    14 years ago
    last modified: 9 years ago

    Lee, good suggestion. I read one account where someone rolled the mat up and inserted it at an angle in his bin. In that configuration he placed the heat directly in the compost while also providing additional aeration through the middle of the compost. I think the mat he used had a probe and thermostat so it could be set at a certain temperature.

    The heat mats are one of the more costly options, but are great for those who have an unused one around.

    Andrew

  • sparkett788
    14 years ago
    last modified: 9 years ago

    Thanks for the links--been looking for good forums and found several that weren't good for advice. I've bookmarked several.
    I was annoyed at my plastic jug because I couldn't get it sealed and I wanted a sealed unit to bury. Added a few drops of hydrogen peroxide to avoid any algae, bacteria, etc. and wouldn't hurt the worms if it did leak. Finally got it sealed--yea! The worms do love it; I find them all gathered around it each time I look to see how things are going. I'm using an old laundry basket, lined with cardboard, and put inside a kitchen cabinet now. They were in a plastic tote until now. I had no holes drilled in the plastic tote, but monitered the moisture carefully. I drilled a few small holes in the bottom of the basket and put it on an old tote lid. Now things get buried directly into the bin. I started out with bedding of cardboard, newspaper, and mostly oak leaves--add a few handfulls of sand, and soil. Worms seemed to be happy from day one--never tried to escape. Been almost 3 months now--and no where near ready to harvest yet. Maybe I haven't kept them warm enough yet? Then again I did notice lots of babies in pockets after reading through some other posts. Started out with 1 lb. of redworms, and hoping for an increase. Only me, but I eat a lot of veggies, and make most stuff from scratch. Don't add dairy, meat, or oil. Sometimes if I get too much I put it in the blender--really gotta watch the blender; can burn up a motor quick. I need more worms! LOL! Hence why I was looking for heat in winter.

  • plumiebear
    Original Author
    14 years ago
    last modified: 9 years ago

    sparkett, it sounds like you're doing fine and the worms could really start to take off now that you've added the heater. Under ideal conditions the worm population can double in 3-4 months, but usually it takes time for a new bin to reach "ideal conditions" (some never reach it). From what I've read, it sounds like once a bin reaches a certain zone, the worm population can really explode. If you can maintain "the zone", 1 lb. quickly becomes 2, then 4 lbs. That's why maurader is starting out with only 100 worms in his bins. He's planning for this worm baby boom.

    Andrew

  • sparkett788
    14 years ago
    last modified: 9 years ago

    Andrew, thanks for the help. I hadn't buried the water jug yet when I posted--it's a slim-line 1 gal jug. So I had to dig them up to bury the jug about 3/4 down--there were worms EVERYWHERE. I know there's a lot more than the original 1000. I had no idea! I have never seen a cocoon and have looked carefully. I think they are just harder to see in my bed of oak leaves. They have easily tripled. I used to have to hunt for them; they were in every inch of that bedding. I'm very excited. They don't seem to eat that much--probably spending their time multiplying. LOL!
    After reading more I thought I didn't have enough water, and misted throughly. Yep, got the little white 'pot worms'. But that should clear up soon with that buried heated jug drying things out a bit, and a bit of shredded paper on top. The jug added too much space and I had to take some out and put back into the tote in the laundry room--but in a cardboard box inside the bin--much nicer. Will be interesting to see any differences. Much smaller population in that box, and no heat. Lets'see how they do compared.
    Again, thanks for the links, help and information! I'm loving this.

  • Shaul
    14 years ago
    last modified: 9 years ago

    We've seen some great ideas for keeping the worms warm: rope lights, aquarium heater in a plastic jug, heated mats and a hot water circulating system using an aquarium heater and a fountain pump. But they all have one weak link: They run on electricity.
    Winter is not just about keeping the worms warm, but also about power outages and not everyone is equipped with emergency backup power. Today the air temp. was 50F with night temps expected to drop to 40F. Bin temp was 55F (my bin is outside).
    As an experiment, I tried a hot-water bottle; it worked surprisingly well. I found a shallow rectangular plastic container, large enough to contain the water bottle, but not so large that I couldn't close the bin cover (a glass casserole dish might work as well). The idea was that, in case of a leak, the boiling water would be contained in the container. The last thing I wanted was boiled worms.
    I set it up at 7am and checked it again at 6pm (11 hrs. later), the water bottle was barely warm. But when I removed the plastic container, there were masses of worms underneath. Yes, this requires work (refilling the bottles at least twice a day), but in a pinch it could mean the difference between saving or losing your herd. I plan to keep 2 water bottles plus a small camping stove and a scrap blanket or two for emergencies.

    Any other ideas?

    Shaul

  • plumiebear
    Original Author
    14 years ago
    last modified: 9 years ago

    Great point, Shaul. I'm in a fairly mild climate so my heating experiment was mostly for fun and to confirm that worms are more active in a warmer environment. It's hard to gauge that since the worms in my unheated flow through bin are pretty active at ~60F. Even harder to gauge is whether the heated bin will increase reproduction. Will the cocoons hatch sooner? There's no way to track that.

    It's raining here this week, but next week I'll try something I've been planning for a while. I'm going to use a solar camp shower as a heater. It's similar to your water bottle except it's black and the water will be heated by the sun. As you say, these methods will require more effort than plugging in a light/heater on a timer. Should we start a separate discussion for heating strategies that do not involve electricity or natural gas/propane? "Solar & other environmentally friendly worm heating methods"? :-) Maybe something more catchy?

    Andrew

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