Colorado Worm Company Vermicompost
Colorado Worm Company Vermicompost
The best worm castings we have ever carried.
Most bagged castings run forty to fifty dollars and you never quite know what is in the bag. These are different, and yes, they cost more. They come from a single family farm in Western Colorado, made in small batches, restocked fresh every couple of weeks, and alive with a level of biology and nutrient density we could not find anywhere else. We were impressed enough to make a full video about them and pay for lab testing to prove it.
Here is exactly what you are paying for.
We are not going to pretend this is a bargain bag. It is a premium product with a premium price, and every dollar has a reason behind it.
One bag of these holds as much phosphorus as about 20 bags of typical worm castings.
Colorado Worm Company
Based on Logan Labs testing of Colorado Worm Company against four popular bagged castings. Watch the side-by-side test
What that looks like on a 15 gallon fabric pot
The Grassroots 15 Gallon Living Soil Pot is 18 inches across. A quarter inch of these on top is about a quart. To get the same phosphorus from typical castings, you would need about 5 inches, more than a full 5 gallon bucket piled on top of your pot. It will not fit. That is why a little of these goes so far, and why you will notice the difference when you use them.
What one bag does
2 Gallon
7top dressings on a 15 gallon pot 32batches of compost tea1/2 Cubic Foot
13top dressings on a 15 gallon pot 60batches of compost tea1 Cubic Foot
27top dressings on a 15 gallon pot 120batches of compost teaApproximate, at a quarter inch top dress on a 15 gallon Grassroots fabric pot and 1 cup per 5 gallon tea batch.
It tested higher, so you use less
We paid for the lab testing ourselves. The people who make these castings did not, because we wanted the real numbers before we stood behind them. It came out well ahead of other bagged castings on nutrient density. Growers tell us over and over that a little goes a long way, which stretches every bag further than the sticker suggests.
Nutrients that are ready to use
Keeping nutrients flowing is one of the hardest parts of growing organically. Dry amendments build the long-term reserve in your soil, but your soil life has to break them down first. These castings have already been through the compost pile and the worm, so the nutrients come pre-digested and ready for a living soil to use right away. The lab shows it: almost all of the nitrogen tested as nitrate, a form roots take up readily. You get serious nutrition and the biology in the same bag.
A living ecosystem, included
Alex hand-adds Red Wigglers to every bag, and each one also carries cocoons along with beneficial life like predator mites and rove beetles. Bought separately, that kind of biology can run hundreds of dollars. Here it comes right along with the compost, ready to take hold in your soil.
Real compost bedding, not dressed-up peat
Most repackagers bed their worms on dark sedge peat that looks like finished castings. Colorado Worm Company beds theirs on fully finished farm compost, the method taught by ClackamasCoot. It is the difference between something that looks the part and something that is the real thing.
Fresh and fast-moving, never stale stock
Alex brings down fresh castings every couple of weeks and screens about a month's supply at a time, which is how you get the best moisture, texture, and packing. It moves fast and does not sit long, so what reaches you is recently made, moist, and full of life instead of last year's leftovers.
One family, one farm, doing it all by hand.
Colorado Worm Company is Alex and his family on a homestead of more than forty acres along the Uncompahgre River south of Montrose. No employees, no shortcuts. Just a true mom and pop operation that decided to make some of the best castings in the country, and then went and did it.
Alex trucked in a load of high quality apple crates and insulated an entire barn to keep the worms happy through Colorado winters. He runs a modest tractor and a trommel that gently separates the finished castings from the worms. He builds windrow thermal compost, turns it, and only once it is fully finished does it become the bedding and feed for his Red Wigglers, who then get fed BuildASoil products on top of that. There are horses on the property, a closed loop system, and about as small a carbon footprint as you will find.
He even drops a few live worms into each bag by hand as he fills it. A big operation could never do that, and that is the point. We have asked Alex more than once to scale up so we could bring the price down, and every time the answer is no. Quality and family come first for him, always. He likes knowing there are living worms riding along inside every bag of his compost, and once you have used it, you understand why.
This is what craft looks like. It is why the results are what they are, and it is why we are proud to carry it.
Do not take our word for it
We funded independent lab testing ourselves and put the full comparison against other castings on video. See the numbers and decide for yourself.
We keep testing. See the October 2026 lab results further down this page.
Guaranteed to arrive moist, rich, and alive.
You do not need a microscope.
There is a lot of talk about putting castings under a scope and guaranteeing a microbe count. We think most of that is noise. Biology is always changing, so a number on a certificate does not tell you much by the time the bag reaches you.
The simpler truth is that you can see life with your own eyes. A dry, lifeless pile looks exactly like what it is. A bag of Colorado Worm Company is the opposite: dark, moist, rich, and clearly alive. Between plain castings scooped from a warehouse and something like this, made from finished thermal compost that is visibly teeming with life, there is no contest for which one is more biologically alive.
One honest note on the worms Alex adds by hand. They burrow and move around, so you may not spot them right away, and a few may not survive the trip. Do not be disappointed if you do not see them wriggling the moment you open the bag. The cocoons ride along too, and once you work this into your garden, worms will start to appear. You will have a living ecosystem in your soil. That is our promise.
Straight from the comment section.
"Nothing but phenomenal results. A little bit goes way further than any other castings I've used."
gubbleguyYouTube comment"If you have it, you are almost guaranteed to get good results. The Colorado worm castings are amazing. I won't use any other ever again."
ORGANIXFARMERINCYouTube comment"I've got a bag of CoWoCo from December 2023 that's about 50% used and there's always a few worms in the bag. Absolutely amazing."
Shepp6769YouTube commentA little goes a long way.
Top dress
This stuff is potent, so a quarter inch layer is all most pots need. On a 15 gallon fabric pot that is about a quart. Refresh it every two weeks to once a month through veg and flower. You can go heavier without burning, but with castings this strong you usually do not need to.
Compost tea
Add about 1 cup per 5 gallons of aerated water for an overall nutrient and biological boost, brew no more than 24 hours, and apply straight to the root zone.
Sizing note: the 2 Gallon bag is about 10 lbs, the 1/2 Cubic Foot about 20 lbs, and the 1 Cubic Foot about 40 lbs.
Pick the amount that fits your grow.
2 Gallon
About 10 lbs1/2 Cubic Foot
About 20 lbs1 Cubic Foot
About 40 lbsBecause a little goes such a long way, even the premium price stretches further than a bag of standard castings. Buy the size that matches how much soil you are feeding.
Put the best in your soil.
When you buy this, you are backing a real family farm doing meticulous, hands-on work, and you are putting the finest castings we have ever tested into your garden. Guaranteed to arrive alive.
Questions first? Our whole team grows, so reach out by chat, email, or phone and we will help you dial it in.
October 2026 lab results
One sample from a current batch, tested by Logan Labs on October 19, 2026. These are numbers for the castings alone, before they go into your soil. Both full reports are linked below.
Phosphorus and potassium come from the Mehlich III test, which Logan Labs reports in pounds per acre. We converted them to ppm here. Every value, in the original units, is in the full reports.
Common questions
Why do these cost more than other worm castings?
One bag holds as much phosphorus as about 20 bags of typical castings, so you use far less. They are made in small batches on a single family farm, bedded on fully finished thermal compost instead of peat, and restocked fresh every couple of weeks.
How much should I use?
For top dressing, a quarter inch layer is all most pots need. On a 15 gallon fabric pot that is about a quart. Refresh it every two weeks to once a month through veg and flower.
For compost tea, use about 1 cup per 5 gallons of aerated water, brew no more than 24 hours, and apply straight to the root zone.
Can I use too much?
You can go heavier without burning your plants. With castings this strong you usually do not need to, so a heavier layer mostly means a bag that runs out sooner.
Are there really live worms in the bag?
Yes. Alex adds Red Wigglers to every bag by hand, and the castings also carry cocoons and other soil life like predator mites and rove beetles. The worms burrow, so you may not see them right away, and a few may not survive the trip. Once you work the castings into your garden, worms will start to appear.
Should I use these to build a new soil?
For building soil in volume, #1 BuildASoil Worm Castings are the better fit, since you can add your nutrients in a balanced way. Colorado Worm Company castings are made for top dressing, compost teas, and using as a small percentage of a soil recipe.
What if my bag does not arrive in good shape?
Every bag is guaranteed to arrive moist, rich, and alive. Contact our support team and we will make it right.
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