We love composting here at Epic Gardening, and we’re huge fans of the worm bin called the Urban Worm Bag. Composting worms are great for turning your kitchen scraps and other food waste into glorious worm castings. But many people are interested in another method: a worm tower.
Worm towers are in-ground permanent solutions for processing food scraps and other food waste, leftover paper and cardboard. But while most would assume that they would work nearly identically to other types of worm bins, particularly the type often referred to as a stacking system, they’re a bit different.
Today we’re going to discuss everything you could ever hope to know about a worm tower system. Perhaps most importantly we’ll describe what it is and how it works. But we’ll also cover whether it’s as effective as other worm bin setups. We’re also going to explore DIY builds you can do to turn free bed space into your own small recycling center!
What Is A Worm Tower?
It sounds deceptively simple: a tube with holes in it that’s stuck in the ground. But in reality, a worm tower can be short or tall, narrow or wide. It can have small holes or large ones; it can have a bottom or be completely bottomless.
A worm farm is normally are set up in an enclosed system. To that system, one would add bedding materials like shredded paper or cardboard, dry fall leaves, or coconut coir. Anything that is carbon-rich can be used as a bedding material. Then, food waste is added. The combination of the carbon-rich materials and the nitrogen-rich food scraps makes for a good blend of materials on which compost worms can feed. If you run out of food waste in your kitchen compost pail, grass clippings will do in a pinch!
But in a worm tower, it’s less about making the perfect living space and more about providing a feeding zone. Since the worms have access to the soil around the tower for living space, what they really require is other organic materials to eat. Tucking a worm tower here or there around your raised beds or setting them deep into your garden bed gives you what amounts to miniature recycling centers. And in theory, you’d get worm castings too… right?
If you’re aiming for a zero-waste household, this sounds like a great idea. And it really can be. But only if it’s done the right way!
Do Worm Towers Work?
There are a few drawbacks to using a worm tower, and these problems are usually what causes someone to give up on using worm towers entirely. But if you plan in advance, you can easily overcome these hurdles and have little worm farms chugging away all through your yard.
Problem 1: Which Worms To Use?
Picking the right worms for a worm bin is relatively easy. We’ve got a fantastic article telling you which worms to use for your regular worm farm. Usually, we recommend red wiggler or European nightcrawler worms, as these are great options even for beginners.
But will those worms work in a worm tower setup, too? The answer is yes… and no.
Yes, regular composting worms can be put in a worm tower, but they require quite a bit of surface space. If you’re trying to use a narrow 4″ PVC pipe as a worm tower, that’s not going to provide enough surface space. And most people don’t want to devote a lot of space in their raised beds to a semi-permanent installation like this.
What is more ideal is if you have natural earth worms in the yard already. The sort of earthworms you find naturally in your soil are usually more accustomed to living in a soil-based environment rather than in the leaf litter and organic matter at the soil’s surface like red wigglers and other compost worms. Since they won’t be living inside the tube, they’ll be able to spread out as needed around it. As they get hungry, they can come through the holes and rummage around inside the tube for scraps. And as the worms eat, your waste is reduced.
You will have to have natural earthworms in your garden already for this to work. Otherwise, you might do better to opt for a more traditional worm system.
Problem 2: Space Is At A Premium
As mentioned above, space is limited. Finding PVC pipe that’s wider than 4″ is difficult, if not impossible. Other types of pipe up to 6″ in diameter are available, but can be hard to find. A 5-gallon bucket can give you a little more surface space if you cut off the bottom or put holes in the bottom, but it’s not very deep.
Ideally, you want your worms to come back over and over to get food out of the pipe, no matter what it’s constructed from. If you’ve already overcome the first problem, the diameter of the pipe is less of a concern. But if you don’t have the right worms in your garden beds, this becomes trickier. Small amounts of worms and bedding can be added to a bucket setup, but anything much narrower won’t support a decent population.
The other problem is that narrow pipes don’t hold much waste. If you fill a pipe to the top, suddenly you begin to have issues with airflow unless you drilled enough air holes in the sides, and you have a bunch of stinky food waste decomposing. With a very small population of red wigglers or other composting worms in there, they won’t be able to keep up, so you’d really have to have an active ground worm population to reduce the waste.
Problem 3: Exposure To The Elements
The sun will be beating down on your worm tower constantly. If it’s buried deep enough, that will provide some protection from heat or cold, but the tower will still heat up. But if it’s raining, you don’t want your tower to fill up with water, so you’ll want to cover it. The lid will trap any heat inside. It’s frustrating!
You’ll need to puzzle out some sort of ventilated lid that keeps most of the excess rainwater out of your tower while still allowing excess heat to vent off. Keep in mind that nitrogen-rich organic material also naturally heats up as it decomposes, so you’ll need that heat vent in place year-round.
Problem 4: Is It Even Safe?
As time has gone on, people have become more concerned with what chemicals are in our plastics. Sure, a food-grade bucket will eliminate most BPA or other potentially-risky materials… but is PVC pipe going to be a problem?
The exterior of a piece of PVC pipe is coated in a waxy coating that prevents it from releasing vinyl chloride into the soil. However, the same is not true of any cut ends. You’ll need to make sure to seal any cut ends with some form of sealant that won’t break down in constant soil moisture as well.
You could opt instead for ABS piping. However, ABS pipes are made with BPA, and if you’re trying to avoid that, that’s not a good option either.
There are alternatives that are much safer, but require some work. You can get rid of plastics altogether by making wooden worm towers, but those will need to be sealed or they will decay over time. Clay pipes are extremely effective, but you’ll need to use extreme caution when you drill holes so you don’t shatter the pipe. Both of these are permaculture-friendly options that can also add lots of visual appeal to your garden.
Of course, you can always just opt for a more common compost bin or tumbler that doesn’t use worms, or for a more standard worm farm option. Those are definitely effective at composting waste as well. But don’t give up on dreams of a tower setup yet, because there are ways to make composting in a tower viable!
Problem 5: There Won’t Be Casting Harvests
Worm castings are touted as one of the best things to add to your garden for many reasons. Just for microbial content alone, they’re much better than many other options. But don’t expect large casting harvests from your tower.
Unlike most other worm compost bins, these are meant for free access for worms to come and go. As worms poop where they are, they will leave a good amount of castings outside of the tower. This is doubly true if you’re using small pipes, as the worms will enter for food and then leave right afterward.
While this means that the soil around the pipe will be getting regular applications of worm castings, it means you won’t be able to harvest them. But for a no-work system, this can be an effective way to compost excess waste.
How To Build Worm Towers
As I said earlier, all of these issues can be resolved… with a little planning. So I’ll describe two basic, non-PVC options for your worms to feast in!
Wooden Tower Construction
The easiest option for most would be to skip the PVC entirely and to opt for a wooden tower. From a permaculture viewpoint, this is the better option as you’re not adding plastics to your soil. You’ll want to seal your wood so it doesn’t absorb water and start to rot, of course. Use linseed oil, tung oil, or any organic-approved sealant to do this if you want to be especially 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 choices for any garden project as it lasts longer than pine or fir. The width of the board will determine the approximate width of your finished tower, so make sure you have garden space planned out for installation.
Drill pilot holes into the wood, then use wood screws to join the boards together with a good electric screwdriver. Once you have your rectangle assembled, use a drill with at least a 1/4″ bit on it to put lots of holes in the portion that will be underground in the garden to allow for worm access. If your worms are fatter than 1/4″, drill larger holes! Make sure you add plenty of them around the entire tower so that it can be accessed from all sides by your garden worm population.
On the portion that will be above ground, you’ll also want to drill to add some ventilation in the sides. These can be done in nice patterns for visual effect, just to make your tower look pretty when it’s done. Try to ensure you have enough holes to allow the tower to release excess heat. These can be smaller than the ones for worm access.
At this point, it’s time to add the tower to your garden bed. Towers like this one are easiest to install by digging a large hole. Set it into place, then backfill around the exterior. Inside, create some starter layers to entice worms to your tower. Even layers of dry leaves or shredded paper with food scraps or grass clippings make for a good beginning point for the worms to visit. Use a little water to wet everything down when you’ve added it, as the worms will like a little bit of moisture!
Now that the frame is in place, it’s time to build the top. Take two pieces of scrap lumber that are a few inches wider than the frame and screw them together in a V shape. Use two small pieces of scrap lumber inside to act as cross-braces and to help keep the top in place. You shouldn’t have the cross-brace pieces go all the way to the top of the V, as leaving a gap allows excess heat to vent off at the top.
Basic Bucket Construction
If you don’t mind plastic, pick up a food-safe bucket and cut the bottom off. Drill holes in the side as well as in the lid, then bury the bucket up to the top. The lid will still act as a rain blocker, and the interior will provide a good composting environment.
These will fill up quickly, but if you’re looking for a home for a few red wiggler worms, this is a great option for you! Your red worms will require regular applications of both carbon-dense materials and nitrogen-dense ones. Layering them in as described before provides a decent home for red worms as well as plenty of food.
If you don’t want to add worms to this bucket bin, any natural garden worms you may find will still get into it. Another good thing about this method is that it can be used for slow composting, even without the worms. Mix up the contents occasionally and even if worms don’t move in, it’ll gradually break down on its own in the garden.
