We love composting here at Epic Gardening, and we're big fans of the worm container called the Urban Worm Bag. Composting worms are great for turning kitchen scraps and other food scraps into gorgeous worm casts. But many people are interested in another method: a worm tower.
Worm towers are permanent solutions for processing leftover food and other food waste, scraps of paper and cardboard. Although most would assume that they would work almost identically to other types of worm containers, especially the type often referred to as the stacking system, they are a little different.
Today we're going to cover everything you could ever want to know about a worm tower system. Perhaps most importantly, we describe what it is and how it works. But we'll also explain whether it's as effective as other worm basket setups. We'll also be exploring DIY builds that you can use to turn free bed space into your own little recycling center!
What is a worm tower?
A look inside a worm tower.
It sounds deceptively simple: a pipe with holes in the floor. In reality, a worm tower can be short or tall, narrow or wide. It can have small or large holes; it can have a bottom or it can be completely bottomless.
A worm farm is usually set up in a closed system. Bedding materials such as shredded paper or cardboard, dry autumn leaves or coconut coconut would be added to this system. Anything rich in carbon can be used as bedding material. Then food waste is added. The combination of the carbon-rich materials and the nitrogen-rich leftovers makes a good mix of materials that compost worms can feed on. If you run out of food waste in your kitchen compost bin, clippings will do in a pinch!
In a worm tower, however, it's less about creating the perfect living space and more about providing a feeding zone. Since the worms have access to the ground around the tower for living space, they really need other organic materials to feed on. If you put a worm tower here or there around your raised beds, or put them deep in your garden bed, you get miniature recycling centers. And in theory you would get worm casts too … right?
If your goal is a waste-free household, this sounds like a great idea. And it really can be. But only if it's done right!
Do worm towers work?
There are a few drawbacks to using a worm tower, and these issues usually result in someone giving up using worm towers entirely. But if you plan ahead, you can easily overcome these hurdles and leave small worm farms chugging in your yard.
Problem 1: Which worms to use?
Red wigglers are popular in conventional worm containers.
Choosing the right worms for a worm container is relatively easy. We have a fantastic article that will tell you what worms to use for your regular worm farm. We usually recommend red wiggler or European nightcrawler worms as these are great options even for beginners.
But do these worms also work in a worm tower? The answer is yes … and no.
Yes, regular composting worms can be put in a worm tower, but they take up a lot of surface space. Trying to use a narrow 4 inch PVC pipe as a screw tower will not provide enough surface space. And most people don't want to use a lot of space in their raised beds for a semi-permanent installation like this one.
It is more ideal if you already have natural earthworms in the yard. The type of earthworms that you naturally find in your soil are usually more used to living in a ground-based environment than in the leaf litter and organic matter on the soil surface such as red wigglers and other compost worms. Since they do not live in the tube, they can spread around them as needed. If they get hungry, they can come through the holes and look for junk in the tube. And when the worms eat, your waste is reduced.
You must already have natural earthworms in your yard for this to work. Otherwise, you'd better go for a more traditional worm system.
Problem 2: space is tight
As mentioned above, space is limited. Finding PVC pipe that is wider than 4 inches is difficult, if not impossible. Other types of tubing up to 6 inches in diameter are available but can be difficult to find. A 5 gallon bucket can give you a little more surface space if you cut off the bottom or poke holes in the bottom, but it's not very deep.
Ideally, you want your worms to keep coming back to get food out of the tube, no matter what it's made of. If you've already solved the first problem, the pipe diameter is less important. However, if you don't have the right worms in your garden beds, it will be more difficult. Small amounts of worms and bedding can be added to a bucket setup, but anything much narrower cannot support a decent population.
The other problem is that narrow pipes don't contain a lot of waste. If you fill a tube to the brim, you suddenly start having problems with airflow unless you've drilled enough air holes in the sides, and it creates a lot of smelly food waste. They can't keep up with a very small population of red wigglers or other composting worms, so you really need an active population of soil worms to reduce waste.
Problem 3: exposure to the elements
Conventional screw containers have much more surface area.
The sun shines constantly on your worm tower. If it's buried deep enough, it will provide some protection from heat or cold, but the tower will heat up anyway. However, when it rains you don't want your tower to fill up with water so you'll want to cover it. The lid stores the heat inside. It is frustrating!
You have to puzzle out some sort of vented lid that will keep most of the excess rainwater out of your tower while also being able to vent the excess heat. Remember that nitrogen-rich organic matter naturally heats up as it decomposes, so you need this heat output year round.
Problem 4: is it safe at all?
Over time, people have paid more attention to what chemicals are in our plastics. Sure, a food grade bucket eliminates most BPA or other potentially hazardous materials … but will PVC pipe be a problem?
The exterior of a piece of PVC pipe is coated with a wax coating that prevents vinyl chloride from getting into the ground. However, the same does not apply to cut ends. You need to make sure that any cut ends are sealed with some kind of sealant that won't break down even with constant soil moisture.
You can opt for ABS piping instead. However, ABS pipes are made with BPA. If you want to avoid this, this is also not a good option.
There are alternatives that are much safer but require some work. You can remove plastics completely by making wooden worm towers. However, these must be sealed, otherwise they will expire over time. Clay pipes are extremely effective, but you must be extremely careful when drilling holes so as not to break the pipe. Both are permaculture-friendly options that can add a ton of visual appeal to your garden as well.
Of course, you can always opt for a more common compost bin or cup that doesn't use worms, or a standard option for the worm farm. These are definitely effective at composting waste as well. But don't give up on your dreams of building a tower just yet, there are ways to make tower composting possible!
Problem 5: There will be no harvest
Worm casts are touted as one of the best things to add to your garden for many reasons. For microbial content only, they are much better than many other options. However, don't expect large casting harvests from your tower.
In contrast to most other vermicompost bins, these are designed for free access for worms to come and go. When worms poop where they are, they leave a good number of castings outside the tower. This is twofold when you use small pipes as the worms enter to eat and leave right afterwards.
While this means worm castings will be regularly added to the soil around the pipe, you will not be able to harvest them. However, for an out of work system, this can be an effective way to compost excess waste.
How to build worm towers
An example of a worm tower design that needs a little more ventilation and a lid.
As I said earlier, with a little planning, all of these problems can be solved. So I'm going to describe two basic non-PVC options that your worms can enjoy!
Wooden tower construction
The easiest option for most would be to skip the PVC entirely and go for a wooden tower. From a permaculture perspective, this is a better option as you don't add plastics to your soil. You want to seal your wood so that it doesn't absorb water and naturally start to rot. Use linseed oil, tung oil, or a bio-approved sealant to do this if you want to be extra careful.
Use 1 "x6", 1 "x8", or 1 "x12" cedar fence boards to construct a long rectangle with open ends. Cedar is one of the best options for any gardening project because it lasts longer than pine or fir. The width of the plate will determine the approximate width of your finished tower. Therefore, make sure that garden areas are planned for the installation.
Drill pilot holes in the wood and join the boards with wood screws using a good electric screwdriver. When you've assembled your rectangle, use a drill bit with at least a 1/4 '' bit bit to put plenty of holes in the part that's underground in the garden to allow access to worms. If your worms are more than 1/4 inch thick, drill bigger holes! Make sure you add plenty of these around the entire tower so your garden worm population can access them from all sides.
On the part that is above the ground, you'll also want to drill to ventilate the sides. These can be created in beautiful patterns for visual effects to make your tower look pretty when finished. Make sure you have enough holes for the tower to give off excess heat. These can be smaller than those for worm access.
At this point, it's time to add the tower to your garden bed. The easiest way to install towers like this one is to dig a large hole. Put it in and refill the outside. Create some starter layers inside to lure worms into your tower. Even layers of dry leaves or shredded paper with leftover food or grass clippings are a good starting point for the worms to visit. Use a little water to moisten everything once you've added it as the worms like a little moisture!
Now that the frame is in place, it's time to build the top. Take two pieces of scrap wood that are a few inches wider than the frame and screw them together in a V shape. Use two small pieces of scrap wood inside to act as cross braces and hold the top in place. The cross braces should not reach the top of the V, as leaving a gap allows excess heat to be dissipated at the top.
Basic bucket construction
If you don't mind plastic, take a food-safe bucket and cut off the bottom. Drill holes in both the side and the lid and bury the bucket up. The lid continues to act as a rain blocker and the interior provides a good composting environment.
These will fill up quickly, but if you are looking for a home for a few red wiggler worms this is a great option for you! Your red worms require regular applications of both carbon-dense and nitrogen-dense materials. If you store them as previously described, red worms will have a good home and plenty to eat.
If you don't want to add worms to this bucket, any natural garden worms you might find will still get in. Another good thing about this method is that it can be used for slow composting even without worms. Mix the contents occasionally and even if no worms get in, it will gradually disintegrate on its own in the garden.
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