How to Make a DIY Worm Tower
Worm towers are in-ground permanent solutions for processing food scraps and other waste products. Horticultural expert Lorin Nielsen explains how worm towers work and how to make your own at home.
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Composting worms are great for turning your kitchen scraps and other food waste into glorious worm castings. This is usually done in a worm farm like the Urban Worm Bag. 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. While most assume they work nearly identically to other types of worm bins (particularly the type often referred to as a stacking system), they’re a bit different.
We’re going to break down everything you need to know about worm tower systems, including DIY builds you can use 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. And, it can have a bottom or be completely bottomless.
A worm farm is typically an enclosed system. Bedding materials like shredded paper or cardboard, dry fall leaves, or coconut coir are added, along with food waste.
The combination of the carbon-rich materials and nitrogen-rich food scraps creates a good blend of materials worms feed on. 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.
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 through your yard.
Problem 1: Which Worms To Use?
Picking the right worms for a worm bin is relatively easy. 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.
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 four-inch PVC pipe as a worm tower, it’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.
It’s preferable to focus on natural earthworms 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. 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, a more traditional worm system is best.
Problem 2: Space Is At A Premium
As mentioned, space is limited. Finding PVC pipe that’s wider than four inches is difficult, if not impossible. Other types of pipe are available, but can be hard to find. A five-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. You really have to have an active groundworm 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. If it’s raining, you don’t want your tower to fill up with water, so you need to cover it, but the lid will trap any heat inside.
To resolve the problem, you need to create a ventilated lid. It should keep most of the excess rainwater out of your tower while 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 Safe?
As time has gone on, people have become more concerned with what chemicals are in our plastics. A food-grade bucket will eliminate most BPA or other potentially-risky materials. But is PVC pipe 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 seal any cut ends with something that won’t break down in constant soil moisture.
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.
For example, 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.
You can always opt for a more common compost bin or tumbler that doesn’t use worms, or for a more standard worm farm option. 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 the soil around the pipe will be getting regular applications of worm castings, you won’t be able to harvest them. But for a no-work system, it’s still an effective way to compost excess waste.
How To Build Worm Towers
All of these issues can be resolved with a little planning. Here are two basic, non-PVC options for your worms to feast in.
Wooden Tower Construction
The easiest option for most is to skip the PVC entirely and opt for a wooden tower. From a permaculture viewpoint, this is the better option as you’re not adding plastics to your soil.
Seal Your Wood
Start by sealing your wood so it doesn’t absorb water and start to rot. Use linseed oil, tung oil, or any organic-approved sealant to do this.
Construct a Rectangle
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. Make sure you have garden space planned out for installation.
Then commence drilling pilot holes into the wood, then use wood screws to join the boards together with a good electric screwdriver.
Drill Holes
Once you have your rectangle assembled, use a drill with at least a 1/4″ bit on it to add holes in the portion that will be underground. This creates gaps for worm access. If your worms are fatter than 1/4″, drill larger holes. Ensure you add plenty of them around the entire tower so that it can be accessed from all sides.
On the portion that will be above ground, drill holes for ventilation. Get creative and add patterns to make your tower look pretty when it’s done. Ensure you have enough holes to allow the tower to release excess heat. These can be smaller than the ones for worm access.
Install
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. Layers of dry leaves or shredded paper with food scraps or grass clippings make for a good beginning point. Use a little water to wet everything down, as the worms will like a little bit of moisture.
Build the Top
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 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.
Final Thoughts
Worm towers aren’t quite the same as worm farms, but they are still a low-maintenance and useful way to boost your soil and compost waste. Follow these easy steps to make your own, slotting them between your plants.