Red Wiggler Breeder Bins - Optimizing for Reproduction
Red Wigglers have an impressive capacity for reproduction.
Theoretically, 500 worms can become 2 and a half million worms in only 6 months.
The goal of a breeder bin is to tap into that potential. This video shows what a breeder bin should look like - lots of worms mating! I count 7 mating pairs in this video.
Later we'll watch another video of the aftermath (possibly from the same breeder bin) and all the baby worms that can be born from a single breeder bin when done correctly.
But first, let's cover the fundamentals behind red wiggler reproduction.
Population Density: A Key Factor for Breeder Bins
Worms need a partner to mate, and if they can't find a partner, then no babies.
You want enough worms that they can find other hot singles in their area, but not so many that they have to compete for available nutrition.
A good starting point for population density is 160 worms per square foot (assuming at least a 3inch depth). This is what I have used with great success.
- Measure the length and width of your container in inches
- Multiply the numbers together
- Divide by 144
- Multiply by 160.
Thats how many worms you want in your breeder bin.
How to Count out Worms for a Breeder Bin
If you are only running a single breeder bin or two, sitting down and counting out individual worms isn't the worst thing.
But if you want to skip that process, or have too many worms to count, you can assume an average weight by counting a number of worms (the higher the better, I usually aim for 75-100).
- Harvest a bunch of worms down to pure worm.
- Grab a small amount that you're willing to count out manually.
- Weigh the total
- Count them one by one, placing them back in the pile with the other worms.
- Divide their total weight by the number of worms you counted for an average weight.
You can then use that average weight to decide "This amount of weight = this many worms.
Be sure to primarily be using sexually mature worms with a visible clitellum - the "band" towards the head of the worm visible in the picture below.
High Nutrition
Worms will not reproduce if they don't feel there is an abundance of nutrients.
The goal here is to make sure the worms in the breeder bin never lack ready-to-eat food.
Some of the most readily available foods for worms include watermelon and other cucurbits, avocados, and high protein animal feeds such as alfalfa meal or chicken crumbles. This will help encourage reproduction.
Typically using alfalfa meal, chicken crumble, etc., will be the easiest to work with in a breeder bin.
Or you can try out Mazuri's earthworm diet, which is a custom made blend designed to provide a whole diet to earthworms. I have used it in my breeder bins before with success, although generally you can find cheaper options locally.
How to Feed a Breeder Bin
You should have some experience keeping a worm colony happy before you attempt a breeder bin, so I won't really talk much about how to feed the worms here, but here are a couple common methods to feed them.
- Sprinkle a light layer of "worm chow," such as alfalfa meal, chicken crumble, or Mazuri worm feed, on top of the bin, which the worms should eat within a couple days, and then replace it as soon as its gone - or almost gone.
- Blend watermelon/cucurbits, sweet potatoes, avocados or other foods your worms have shown they love, and pour a couple lines down the surface of your breeder bin. Replace as soon as its gone.
High Moisture
Breeder bins perform best if kept a bit more moist than other situations.
A moisture content close to 80% saturated is optimal for breeding.
Organic matter has a certain capacity amount of pore space that can absorb water. But when its not holding water its actually holding air - kind of like a sponge.
So you want most of the pore space (80%) holding water, but not totally saturated so that the water doesn't displace all of the air out of the material.
Don't overdo it though, if it gets too wet the breeder bin will totally fail.
Again, breeder bins are a bit of an advanced technique, so if you're not familiar with what 80% moisture may feel like you may want to go back to some of the basics.
Temperature
25 degrees Celsius, or 77 degrees Fahrenheit is the proven best temperature for reproduction.
Reproduction increases linearly up to 77, but rapidly drops off if you go too much over that temperature, so aiming for a bit cooler, like 70 degrees, isn't a bad idea. You'll still get good reproduction without risking going too warm.
Results from a Successful Breeder Bin
Although it's not likely to hit these numbers, a red wiggler worm can lay 3 cocoons per week, each having about 3 baby worms inside.
If you run a breeder bin for 3 weeks, you will 27x your initial population if the worms breed at their best possible rates during that time.
On our other post about red wiggler reproduction, you'll see that, theoretically, 500 worms can become 1 billion in just under a year.
Can Worms Reproduce Too Much?
Generally, worms self regulate their population, so they don't normally get to a point where they have too many worms. BUT, with breeder bins its a different story..
When the red wigglers lay a massive amount of cocoons, there's going to be a massive amount of mouths to feed once they all hatch.
If the bin isn't big enough to add enough nutrition to feed them all, their growth will be stunted and some may even die.
So know that breeder bins are for hyper-optimized reproduction and you will need to account for a population explosion.
If you don't want that many more worms, just stick with the basics of treating the worms well and they'll reproduce steadily over time to a stable population.
Want to start your own breeder bin? Let us know you want sexually mature red wigglers only and we'll do our best to accomodate.
Scott Kent
Owner of Hungry Worms. Worm farmer, soil microbiologist, and educator since 2014. Read more about me here.