I don't use multi-tier wormbins, I use regular RM bins, and I usually harvest once a year, or sometimes only once every other year. I harvest side to side - feeding one end, harvesting out of the other. I'm not in any hurry, because I've been keeping worms for 20+ years, and so I just get into a rhythm of feeding, overlooking the situation, and harvesting compost when the bin(s) fill up.

I had a 4 tier RM (9 gal.size) bin and I harvested one bin each month on rotation (4 months old and full to 1" from the rim). Worm population between 1.25 to 1.75 lbs.

What brand multi-tier worm bin do you have, Kendra?

I have a 3 tier Can-of-Worms and harvest the first day of every month. This means the bin to be harvested is 3 months old. Sometimes it is processed very well and other times, like April 1st, not so much. So it goes back on top and goes through the 3 months again. I did get to harvest almost 1/2 of the bin so it wasn't a total loss.

Have a regular bin same as priswell and just as long going. I harvest every 6 mos from one end or the other.

I know this post is old, but I thought I would add my experience to it. I've got two Worm Factory 360's and love them. I harvest one tier from each system every month (at least) and during the warm months when we have even more fresh produce, can harvest even more frequently. I think the tiered systems pay for themselves in ease of harvesting. I simply put the tier to be harvested on top without a lid, shine a bright light on it, and the worms go down deeper into the lower tray. Very easy.

Dumb Aussie here but what is a rm bin....? Is that round metal or something else?

RM is short for "Rubbermaid", a manufacturer of plastic products such as large totes used to make worm bins.

Ok thanks for the clarification

I have a 6 tier 360 going and could do it every week but its usually between 2-4 weeks. and sometimes I do 2 trays at once.

Hummersteve, just curious as too what volume of castings you get out of each tier when you harvest that often? Sounds like your worms are putting in lots of overtime!

Harry

Harry757, I have the same system that Hummersteve has and the trays are 14 x 14" and about 5 or 6" deep/tall. So once it's all turned into castings that is about the volume you're getting with each tray. If I had to guess, it would fill about 1.5 to 2 gallon sized zip Locks?

Nicole, does your 360 produce castings at a rate similar to Hummersteve's? One or two gallons every 2-4 weeks sounds like a lot. Do you keep your harvested castings in sealed zip-lock bags? If I put my castings in anything plastic I always drill/melt holes to allow some air circulation. Do they get a bit "wiffy" when sealed up for extended periods?

Harry

Harry757, no I wouldn't say I produce quite that much. But I'm also not managing them intensively so I would think it is possible. I allow the worms to work the trays until I get 4 trays stacked up. By that time, the lower two trays are well finished and I harvest two at a time. I guess I do this every 2-3 months. I keep the finished castings in a tub trug there in the basement. I do not close them up or they get smelly. My castings tend to be fairly wet when I harvest them too (again, not intensively managed...) so the tub trug allows them to dry out by the time I use them in spring.

Only been worm farming for just over a year and half now and currently have six 30 gallon totes in operation... So far, I've noticed that production rate really drops off during the winter (I keep them in the garage during a Michigan winter)... after the first winter (Oct to May) I harvested maybe 25-30 gallons... just 5 months later (in Oct) I harvested 90 gallons. From the looks of things I will likely harvest another 90 gallons if I wait until July (that would be about 9 months total). Thus far, I've mostly judged when to harvest by the percentage of the bin I think has been converted into castings... I'll run everything in the top 12" of the bin through a 1/4" mesh screen and whatever falls through into the wheel barrow below (worms included) ends up in the garden... its a very simple system. Other than about 4 gallons stored in an open bucket for potting-up containers, etc... all the rest goes straight from wheel barrow into the garden.

So how do you keep your worm population high enough if you're not separating the worms from your castings before dumping into your garden beds?

Harry

Okay, so here's the whole procedure...

I carry the totes out into the sunshine and let it sit for an hour or so (allowing the surface to heat up and dry out enough that the majority of the worms are inclined to go deeper) then I begin by scraping about a 1-2" layer off the top of each bin and putting that into the screened frame I have sitting on top of the wheel barrow. I then shift the castings around back and forth until most of what's going to pass through the 1/4" screen has done so... by then maybe 20-30 minutes has elapsed and I'm back to the first bin and I simply repeat the process perhaps another 7, 8, or 9 times to the point where I begin to run into much larger populations of escaping worms. Whenever the wheel barrow gets near filled I go dump it in the garden... this happens like three times for 90 gallons. Then I stop... put the bins back in the shade and add 4-6" of coco coir and top it with shredded paper and put the lids back on. Then I go inside and collapse for a few. That's the whole process... it takes up a goodly part of my day.

I'll estimate I "lose" maybe 5-10% or so of the worm bin population to the garden in the process... a win-win for those worms and the garden plants wouldn't you think? Its only a broad guesstimate mind you but I likely have 4-5 lbs of worms in each bin to start with so whatever is lost is going to be good for the remaining population in their reduced post-harvest bedding volume and I assume they are to be quickly replaced... Think about this... I'll grab out a gob on occasion just to feed to my koi (if you dig around in a bin you can usually find a ball of pure worms without getting all the castings in-between, those are the ones I scoop up to feed to the fish... I limit it to usually no more than a hundred or so per feeding). I don't sweat the losses since each bin is so large and densely populated that their numbers are easily buffered by littler ones to absorb those losses. Remember because population growth is exponential its only the percentage of loss that one should focus on and not the actual count of individual worms lost in the process.

Of Course I have a lot of worms as the herd has been building over about 4 yrs time. It does depend on how much I load up the trays and its not always the same, but I would guess an avg. of 2gal or less from each tray.

I save the castings for gardening which I share it with my brother and sister. Over the winter after I have depleted the castings I usually have 4 5gal buckets full of castings by spring to use for gardening.

hummersteve, with four 5gal containers of castings produced through the winter months, does that mean you have your bins are inside or do you have a climate mild enough to have them outside all winter? That sounds like great production for the winter months!

Also curious as to how much of a visible difference your addition of castings makes to the vitality of your plants. I add my castings to plants as well but can't say as I've really noticed any amazing increase in growth or fruit/veggie production - have you or your siblings? Of course I haven't exactly tried a side-by-side comparison of plants with vs. without castings.

Harry

........oops.......just read your comment re "castings as fertilizer". So you have actually seen marked signs of improvement with castings alone. Good to hear. Would you agree though, as many have stated before, that castings are more of a soil enhancer than a direct provider of plant nutrients? Guess I'm always trying to find ways to grow healthy/productive plants without having to buy any fertilizers - even organic.

I think you're making a distinction between "fertilizer" and "soil enhancer" that doesn't exist. Worm castings really do provide N-P-K just like any other organic or chemical fertilizer does, and they provide those nutrients in plant-available forms. The difficulty is knowing exactly how much of these elements any given batch of vermicompost will provide, since the exact proportions will depend on what the worms originally ate. You would not get a consistent result unless you were in a large industrial operation where the worms always got exactly the same thing.

Here is a somewhat painfully written article that talks about the variation:

http://www.gardenandgreenhouse.net/articles/may-2013/the-fertilizer-value-of-worm-castings/