Worm Farm Composting (Vermicomposting)

Worm farming and vermicomposting

Thinking about experimenting with worm farming? Check out our introduction to worm farm composting (vermicomposting) at home, including our experiences to date using worm farming bins and buried worm towers.

Composting vs. Vermicomposting

In both worm farming and traditional composting, microbial breakdown is the key to converting scrap plant materials into nutrient-rich compost. In a worm farm, worm activity and dining helps to aerate as well as break down the plant materials into smaller pieces (some of which go through their digestive systems and out again), assisting the decomposition process.  Worm farming is easy to do at home, but your new swarm of wiggly worm “pets” will need to be fed and protected from weather extremes, depending on your climate. We’ll talk more about all that below.

The greatest benefit for many home composters is that worm farming allows you to continually compost small quantities without the need for multiple bins, rotation, or turning. When properly tended, worm warms don’t smell and have minimal issues with insects, making them good options for small spaces or potentially even indoors with the right bin construct.

If you general a lot of green waste; however, you’ll quickly discover that a worm farm along won’t be enough to manage your outputs. Most of the activity in a worm farm occurs on the surface layer, so even though the worms accelerate the overall breakdown process, you can only incrementally add small amounts.  Even with our two person household, a worm farm isn’t sufficient for what I would consider to be “high value” compostable kitchen and garden waste. We use a multiple system construct of worm farming, composting, and green waste collection.

Traditional compost piles and bins can get very warm during decomposition, which helps to eliminate pathogens, kill weeds, and deactivate seeds. Just like solarising garden soil, hot composting can help clean and semi-sterilise. Worm farming is a cooler breakdown process, which is great for the worms and for some beneficial microbes, but means that you should be more cautious about what is added to the bin and how the outputs are handled and used.

Selecting Worm Farm Containers

Choosing a Worm Farm

You can buy a ready-made worm farm (we did) or make your own bins to act as containers for your vermicomposting process.  To help decide on potential options, considerations include:

  • Where you plan to keep your worm farm(s),
  • Whether they need to be mobile (e.g. relocated indoors during freezing winter conditions)
  • What features are important to you from a user perspective, and
  • Your budget constraints.  

Ready Made Worm Farms

Ready made worm farms have the advantage of being made for purpose, including easy draining and/or access to completed compost (depending on the design) and stabilised materials for long term use. Where we live in New Zealand, our temperates allow year round outdoor worm farming, but our UV levels can be extremely hard on materials. The downside is that most quality ready-made products they are way more expensive than building your own homemade worm farm.

DIY Worm Farms

To create your own worm farm, at minimum, you’ll need two containers: a primary bin for the worm farm and some sort of secondary container to act as the catch basin for liquid that leaches out of the worm farm during the overcompensating process. If your worm farm is being placed directly on or in the ground (like our buried worm tower), you don’t need the catch basin. The primary bin should be opaque (worms prefer the dark) and will a few modifications, including air holes in the upper portion of the bin and drain holes to allow the liquid out through the base of the bin. You can use screening materials to keep your wiggly worms from launching an escape and/or to screen the drains, if needed.

DIY Worm Farm Inspiration and Ideas

If you’re keen on DIY (or constrained on budget), don’t be intimidated by the idea of making your own. Many of the popular commercial designs (including the Hungry Bin, which we bought) started as experimental DIY designs. Here are some links and ideas to help get you inspired:

Our Current Home Vermicomposting Worm Farms

I’m going to talk about a few products here, but this is not a sponsored post. These are the worm farming products we personally selected, bought, and currently use at home based upon our space and conditions in our own family garden. They have pros but also cons, and I’ll talk about both.

The Hungry Bin

After a lot (a LOT) of deliberation, we opted for a Hungry Bin as our primary worm farm. They’re very expensive, but very well made and admittedly, I really like the ability to remove compost from the bottom of the bin without needing to manually handle the upper layers or (shudders) handle all the worms. I also like that they are semi-mobile. A full hungry bin isn’t light for rolling, especially if you normally keep it on a semi-soft garden surface.  It works great, and I like the ability to easily use both the liquid and finished compost; however, even with a very happy healthy worm population the processing volume is very limited. It’s not a hungry as I would have hoped, but other wise good.

Setting up a Hungry Bin worm farm home composter

Setting Up the Hungry Bin:

The Hungry Bin was very easy to assembly. I did it myself unassisted, and had the bin assembled, positioned, filled, and worms settling in within around an hour. I also liked the minimal packaging, which was fully recyclable, although I reused a piece of the cardboard box for use as a temporary blanket while my worms settled in.

Feeding the Hungry Bin:

The Hungry Bin is our primary worm farm. I use it for high value compost only, as it is nowhere need sufficient in capacity to deal with both kitchen scraps and the huge amount of green waste that comes with moving, trimming, pruning, weeding, and rotation of plants in our suburban garden. Clean food scraps are my primary feeder for the Hungry Bin. Most green waste goes to the standard composting and/or green waste collection bins.

Using the Outputs: 

Using then outputs, both leachate and compost, is very easy with the Hungry Bin. This is one of the strongest positive features of the bin, in my opinion. I was (admittedly) very nervous the first time I unclipped the compost tray from the bottom of the bin, but to my relief it separated easily filled with good looking compost and the rest of the bin contents didn’t tumble out with it. Whew! I’ll talk more about usage below.  The main downside is that compost is a (sometimes painfully) slow periodic delivery in small quantities.

The Verdict:

  • PROS: Easy set-up, mobile, durable, low maintenance, easy use, very easy output collection.
  • CONS: Very expensive. Limited quantities. 

The Tui Worm Tower

I also received a Tui Worm Tower as a gift from hubby. Instead of being maintained as an above ground bin, the tower is buried in the garden where nutrients can seep directly back into the soil. They’re very small, so worm activity area for composting is limited; however, they’re rather nifty. There are no kids at our place, but I think these would be particularly interesting for kids who are old enough to safely participate in the family composting process.

Setting up a Tui worm tower buried worm farm in the garden

Setting Up the Tui Worm Tower:

Assembly wasn’t a factor in this super simple little worm tower. The hardest part was digging a deep hole in my horrible clay soil. It needs all the soil conditioning help it can get! For the safety of my wiggly new guests, I mounded the tower slightly so that they had some protection in the upper portion of the tower in the even of extra wet weather and soggy soil.

You’ll notice in the collage above that my digging and installation was intently supervised by tyhe dogs. That day, senior Oli, sidekick Humphrey, and puppy pal garden guest Cooper were all keenly monitoring the digging action. The installed tower was actually very secure and the dog were unable to disturb the tower or lid. A definite positive in our garden!

Feeding the Worm Tower:

The tower is just a wee little worm farm, so feeding quantities are very small. You could use several on rotation for higher quantity. The rest of my comments on feeding are the same as for the Hungry Bin regarding low volumes of high quality food scraps.

Using the Outputs: 

Being in ground, it composts and seeps directly, making it extremely low maintenance (except when moving). Again, it is very small, but it is also (digging not withstanding) relatively easy to move around and incrementally condition different areas of the garden. 

The Verdict:

  • PROS: Easy set-up, semi-mobile, durable, low maintenance, easy use.
  • CONS: Very limited quantities. Periodic relocation recommended.
In ground buried worm farm tower

Worm Selection and Care

Earthworms vs. Composting Worms

Our garden pals the earthworms like to live and burrow through garden soil. They’re great for soil conditioning, but not the type of worms we want for high volume composting. These surface feeding worms feed on decomposing material in the upper layers of the soil or, in our case, the worm farm. I bought a started pack of Tiger Worms for our warm farms, and the population has been thriving and growing since they moved in. 

Feeding Composting Worms

Since composting worms are active in the top 10-30 cm of the soil and material, feeding should be moderated to ensure that they are able to fully break down the added material before it rots or attracts pests. Generally, no more that a few centimeters of fresh material is recommended, which is why teh surface area of bins is such a limiting factor in worm farm capacity.

Worms can eat their body weight in food a day, so slow sustained feeding every day or two is best for most worm farms.  Keep things clean with plant matter and scraps only, supported with some shredded uncoated paper, dried straw or leaves, and/or untreated wood shavings if/as needed to maintain balance and aeration. For best results, any strongly acidic or spicy plant material is better relegated to the compost instead of the worm farm. I make an exception for the occasional addition of coffee grounds, as the worms seem to love their coffee almost as much as we do. 

Stick to the worm’s preferred favourite for a happy healthy population, rapid consumption, and to keep the bin in balance. Smaller pieces are easier for the worms to break down, so chopping or shredding scraps will help to keep the bin moving quickly.

Wet Weather

The cover of the worm farms helps to keep the majority of the rain out of the bins, but some may still seep in through the air holes. Drainage is important to ensure that the bottom layers of the worm farm don’t flood or become soggy. Depending on the design of your worm farm, you may also need to include some objects to act as flood ramps (upturned terracotta pots are popular options) at the base of your bins to help the worms move to drier upper layers.

Sizzling Summer Worm Farm Support

Positioning the worm farm in a sheltered position can make a huge difference to the ambient conditions for your worms. A hot bin in direct summer sun can be deadly. Relocation, shade cloth, or reflective wrappings can help reduce the head. The worm farms may need added water and/or frozen ice blocks to help maintain moisture levels and/or moderate temperatures.

I keep my Hungry Bin tucked in a shaded area behind the glasshouse, protected from the afternoon sun. It also helps to shield the bin from the harshest winter winds and frosts. In the winter, the nearby brambles have lost their leaves, so the morning sun hits the bin for extra support (see more on freezing conditions below).

Freezing Winter Conditions

Depending on your weather conditions, you may be able to worm farm all year round outdoors (we do). In borderline areas, buried farms can take advantage of the protection of the surrounding soil to help moderate the temperatures, as long as they are above the waterline.  In less temperate areas, you may need to be able to relocate the worm farm for the winter to avoid freezing. 

Unwanted Insects and Pests

A well-balanced worm farm shouldn’t stink (ours smell like dirt) or have bugs. Only once thus far have we had issues with bugs, and that was when the bin was getting more summer fruit waste than it should have, drawing in flies. Most issues are easily rebalanced with covering, turning, time,  and (if needed) adding a worm farm, conditioned to correct pH imbalanced. The Hungry Bin FAQ includes handy trooubleshooting tips.

Composting worms in a new worm farm

Worm Wee, Lechate, and Worm Tea

Liquid “Fertiliser” from Worm Farms

As moist plant material is decomposed, the liquid seeps through the worm farm and out the drain holes in the bottom. The drainage is essential to avoid having a soggy sludge build at the base of your worm farm instead of moist finished compost. This liquid is leachate – part worm pee, part leached liquid, seeped rainwater, and potentially added water if you’ve needed to moisten the worm farm. Worm tea, on the other hand, is brewed by soaking finished vermicompost and castings, not directly harvested from the worm farm.

Using Leachate in the Garden

In a buried worm farm, this goes directly back into the soil. In a bin style worm farm, it can be harvested for use. Its usability depends a lot of whether your worm farm is healthy and balance, and what you’ve added for composting. As noted in the introduction about composting vs. vermicomposting, low temperature worm farms are not as effective at killing off pathogens as hot composting, so there is always some risk with the outputs – solid or liquid.

As a safety compromise, leachate can be diluted for use as a soil applied conditioner and tonic. Since the content is variable, dilution helps reduce the risk of over application. Soil application helps to reduce the risk of introducing unwanted microorganisms directly to your plants’ foliage, in the same was as if plant matter was naturally breaking down on the soil surface around them instead of gathered for the bin. Personally, I also avoid application on/near any of our fast producing edibles as well, although it does get used on the soil around our larger shrubs and fruiting trees.

Using the Completed Vermicompost

Compost Output from the Worm Farm

The completed compost at the base of the worm farm (lifted or funnelled, depending on the bin construct) is a combination of worm castings and directly decomposed compost. In our experience, it looks very much like an extra moist version of purchased compost mix – dark, rick, earthy, and no stinky smells.  It’s extra moist because it’s been soaked through with seeping leachate, so I generally apply the same cautions as I note above for use and handling.

Finished compost bin extracted from the bottom of a Hungry Bin worm farm

Collecting Compost for Use

Collecting the compost for use is a definite advantage of both the buried towers (left the top composting layer for relocation, leaving the finished compost buried behind) and the Hungry Bin’s funnelled design with removable bottom compost tray, as shown above. If you have a stacking worm farm, you’ll need to shift the upper layers and separate your worms from your compost. Not my idea of fun. This is actually one of the main reasons that I chose to buy the expensive Hungry Bin. It’s very easy to collect and use the compost, no fussing with worms, no emptying of bins. Excellent.

High Quality Small Quantity Compost

The output is a periodic delivery of a small quantity of high quality compost. I use it as a top dressing or to blend through garden potting or bedding soil after use and before replanting.  

Is Worm Farming Worth It?

Despite my grumblings above about quantity and safety cautions on usage, I personally think that it is worth the effort. For a small urban property, no smell home composting is definitely a plus! For a larger active garden, it’s more useful as one part of a more comprehensive system that allows rapid incremental composting of high value clean material for vermicompost plus leachate and/or tea as liquid fertiliser. The liquid fertiliser aspect has been a really great value added free resource for our garden. The worm farms definitely don’t, however, replace the need for managing large volumes of green waste from mowing, pruning, trimming, leaf fall, or seasonal garden bed rotations. 

Vermicomposting and worm farming


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