Last issue, we learned how to build a worm bin using five-gallon buckets or storage totes. Worms, worm bins, and compost tea are critical pieces in my repertoire for building regenerative soil. This issue, we’ll cover basic worm bin maintenance and how to harvest the worm castings. Worms are super easy. As caretakers, we’re responsible for keeping the worm bedding moist, feeding our worms, and switching out the worm bedding when it’s fully converted to castings.
One of my secrets to raising worms successfully in our desert environment is using coconut husk as part of my bedding material, because it retains water very well. Moist bedding is critical for keeping worms alive. If, for whatever reason, your worm bin does dry out, don’t freak out. It doesn’t mean that all is lost. It doesn’t even mean you have to buy new worms. Worms will begin to reproduce if they sense that the worm bedding is going to dry out. It’s a survival mechanism and many commercial worm operations utilize semidry worm bedding to trigger this breeding behavior. Let’s say that you’ve left town for a week and when you come back the worm bedding has dried out. Simply rehydrate the bedding and you’ll start to see baby worms within two weeks.
Why are my worms escaping? If you have a worm mutiny on your hands, where they are literally crawling their way out, it could mean several things. If the food we’re using to feed them is too acidic, they will try to escape the bin. If this is the case, remove the acidic food from the bin. Worms will also escape if the bedding is too wet, if you’re overfeeding your worms, or there isn’t enough ventilation. Mold will begin to grow if the worm bin isn’t getting enough oxygen—and it will stink. Luckily, these are easy fixes. Simply drill more holes into the lid, add fresh, unmoistened bedding to the top to soak up the excess moisture, and avoid acidic foods.
How do I know when my worm castings are ready to use? I look for four clear signs that let me know my worm castings are ready for harvesting. The first sign is a deep, dark brown-to-light black color. A very dark black tone is a red flag. Because the worms’ manure is toxic to them, it can kill them off. I have killed thousands of worms by letting the castings cure for too long. The second sign I look for is worm population and how they are breeding. In the beginning of the cycle, when you have new bedding in your worm bin, the worms will explode in number very rapidly. It will seem like your worms breed with every feeding. As the bedding turns into castings, the worms will begin to stop breeding. It is important to notice when this shift happens in your worm bin. At a certain point you’ll start to see less mature egg sacs and worms in the worm bin. Harvest the castings before the worms start to die off, at first signs of their numbers dwindling. Third, if the worms begin to decrease in size, harvest. Too much manure in the bin will stunt their growth. Finally, does the top of the worm bin look like the surface of a billiard table? It may sound crazy, but this is the best way I can describe it: It really looks like a felt surface. I’ve found this to be a good indicator that the worm bin is ready to harvest.
If you’re seeing two or three of these at the same time, it could mean that the worm castings are past their microbial “prime.” It’s important to harvest the castings when they’re the most microbially active—this is healthier for the worms and soil.
Now that you know when to harvest your worm castings, let’s learn how to harvest them.
The most common way to harvest worm castings is using the migration strategy. This is my favorite way to harvest worm castings, because it requires minimal labor on my part. Simply bury a regular feeding in one corner of the bin, wait for the worms to move in to eat it, and then scoop out the other side of the worm bin. Of course not all the worms will migrate, but that’s O.K. The worms that don’t migrate will be planted in the garden.
The photosensitivity method is for folks that don’t want to touch worms. You simply form worm castings into a loose cone shape and shine a light on it. Why? Worms don’t like light and will “run away” from it. You’ll need a table that can get dirty. Scoop a good pile of your finished worm castings on the table, forming them into a loose cone shape. Then shine a very bright light on the pile; as they try to escape from the edges, shine the light on them guiding the worms to the base of the cone. After you move the worms down to the base, scoop the top of the cone for wormless worm castings.
What I like to call the “quick and dirty” is sifting worms by hand. Make sure the worms have completely finished their last feeding. Dump the entire contents of the worm bin on a tarp, or a surface that can get dirty, and start removing the worms by hand. Before I start, I prepare fresh worm bedding, so that I can fill my worm bin right after dumping the finished castings. This way my worms aren’t sitting in a cup, or bucket, outside while I’m going through all the castings. I only bother saving the bigger worms, because these are more likely to lay eggs. By focusing on saving worms that are better for breeding, the process goes pretty fast. I look for large worms with a visible band.
Raising worms is perfect for small children, renters, hobby gardeners, and even the pros. According to the City of Tucson, 80 percent of the materials we send to the landfill can be composted, recycled, or reused. We are throwing away valuable resources that we can use to heal our landscape. It’s critical that we take an honest look at all the food we throw away, whether it’s food scraps from the dinner table or rotten food from the fridge. ✜
How to make a compost tea brewer:
To get the most value out of your worm castings, and the labor that went into producing them, I recommend making compost tea. You can convert a half gallon of worm castings into enough fertilizer for an entire acre. How? Simply water down your compost tea nine parts water to one part tea. This works out to a half-gallon of compost tea for a five-gallon bucket. Are you making potting mix for planters? Expand coconut-husk bricks with compost tea. This inoculates the coconut husk with billions of beneficial microbes that will feed the plants in my container gardens. Compost tea made from worm castings can heal sickly plants, too. In a previous article, I covered how to brew compost tea. Now let’s learn how to build a compost tea brewer.
You can find many of these supplies from Growers House or Sprinkler World. You’ll need:
‒1 five-gallon bucket and lid.
‒An EcoPlus Commercial Air 1 pump, around $40. These pumps are very quiet and will last forever. If you need a more affordable option, find a battery-operated Bubble Box, which is a portable live bait pump for fishing. You can find these at any big box store with a decent sporting goods section. These portable, battery-operated pumps are designed to clip onto five-gallon buckets and aerate them to keep fishing bait alive. You can find them for $8. They include an air stone and get the job done.
‒2-3 feet of ¼-inch clear air tubing.
‒1 six-inch EcoPlus Air Stone Disc (also from Growers House for around $17). A cheaper option is to use adjustable landscaping “shrubblers.” You don’t need any of this if you decided to go with the Bubble Box portable air pump.
‒5¼ inch goof plugs to plug the air lines we won’t need.
‒A five-gallon paint strainer bag for placing worm castings into.
‒A swing check valve for ¼-inch air tubing, from the aquarium section of any big box pet store. This is optional, but it will allow you to place your pump on the floor without liquid getting into it and only costs $3.
Cut a notch at the top of the five-gallon bucket to accommodate the ¼-inch air tubing when the lid is snapped into place. I use my Leatherman’s (Sidekick model) pruning saw blade to cut into the rim. Use the pliers on the Leatherman to get the rectangular plastic strip off of the bucket.
A notch in the lip of the lid will accommodate the large (six-inch) air stone disc, or any other air stone, easily. The EcoPlus Commercial Air 1 pump comes with a manifold that has the options to run up to six lines. If I’m using landscaping shrubblers, I’ll run three to four lines to my bucket (bigger notch in the bucket), but I only need one line if I’m using the six-inch air stone disc. How many lines I run into my bucket for aeration will dictate how many swing check valves I’ll need. The swing check valve keeps water from going into the air pump. It allows us to place it on the floor and have some security. I like having this option for teas that I know will foam over.
If you don’t have a swing check valve, it is critical to place the pump higher than the water level in the bucket. If it’s lower, and there is no swing check valve, water will get into the pump and ruin it. Most folks place it right on top of the five-gallon bucket lid (hence the notch on the side and not drilling holes into the lid). Once the swing check valves are installed, on the lines going into the brewer, it’s time to plug the rest of the outlets. You want to install a small strip of the ¼-inch air tubing on the remaining outlets, with a ¼-inch goof plug at the end, so the only outlets pushing air are in the five-gallon bucket.
Zotero Citlalcoatl is a permaculture designer and herbalist of the Sonoran Desert. Follow him on Instagram @the_sonoran_desert_grower.