After a failed attempt at a worm farm many years ago (I now know lack of drainage was most probably the reason) Brett and I did a lot of research before making the farms we use now. We knew we needed to grow enough worms to eat the masses of daily kitchen waste that we produce, with the hope we would also be rewarded with a bit of worm juice and worm castings. Our expectations were well and truly superseded, because our worms eat ALL of the kitchen waste that comes from the house (this is a lot, a bucket every two or three days) and we have so much worm juice it is often overflowing in its tray when I go to check it. The castings aren't as prolific, but they are super rich and are such a good soil additive, that a little amount makes a big impact, especially when used in and on top of the soil where new plants and seedlings will be going.
One of our worm farms is made from an old bathtub, and the other is made from an old washing machine. The bathtub farm gives us all that beautiful worm juice, and a substantial amount of the castings, while the washing machine farm seems to have become a worm growing factory, so if we need to supply anyone with worms (like we did recently with our local school where Brett teaches) we can do so. I sometimes also use these worms to add to my compost or a garden that needs help breaking down spent plants and dug in mulch. There are also plenty of castings in the washing machine farm, it is just a matter of wading through the masses of worms to get to it all!
The Bathtub Worm Farm
The bathtub farm doubles as a garden seat when the lid is closed, and ours is at the bottom of the garden in a bright sunny position, where it is surrounded by plants and protected by a hedge, which keeps the environment temperate. If it was in an exposed area with no shelter or protection it could become too hot in the summer for the worms to survive.
To make the bathtub worm farm, we first had to source an old bath – when doing this you want to make sure it is still intact with a plug hole and no cracks. Brett then built a frame to sit the bath in. When building the frame, you will need to raise it up like we did to allow for a tray to fit under the plughole. Because this is where the worm juice collects, the bath will have to be high enough for the tray to comfortably slide out from underneath. Once we put ours into its frame, Brett used an old hardwood door as a lid to attach to the frame via hinges at the back.
It's important not to use treated wood anywhere the worms could get to, and it is equally important to make sure there is no gap between the lid and the frame as you don't want rodents or water getting in. Overlapping the lid at the top is a good solution so that the rain drains off - instead of into - the bath.
The next thing we did was made a false bottom on the inside of the bath with wire mesh to raise the bed the worms will be living in up. This ensures the worm wee drains down the plughole without food scraps and worm castings clogging it up and potentially drowning some of the worms. Sitting bricks under the mesh keeps it in place so it doesn’t sag. We then placed green windbreak over the top of the mesh, but shadecloth would also work, just something to allow worm wee to drain through.
After that we made a nice “bed” for the worms. I started with a thick layer of straw, and then some cow manure – not too much, I just dotted it here and there, before adding my first couple of buckets of food scraps, followed by the tiger worms.
Common garden worms will not like being in a worm farm as the food scraps are far too acidic for them, so you need to source tiger worms that thrive on acidic foods. You can buy them online, but if you know somebody else with a worm farm, just see if you can fish a cup or so of worms out of theirs. If you have a good compost brewing away, you may find you already have tiger worms. You will know how to tell them apart from common garden worms because they have distinctive tiger like red stripes on them, hence the name!
Once you have placed the worms in, layer cardboard or old sacks over the top of everything, and water the top well so it is completely damp. This helps to stabilise the temperature and will help the whole farm stay moist. Over summer you will have to keep an eye that this top layer doesn’t dry out – if it does just water it again.
Initially I began by putting the food scraps evenly over the whole surface of the bath, but now I fill up one side with food scraps, then once that half is full, I leave it alone and begin to fill the other side. This way I always have one side with the worms busy eating and converting the scraps into castings, and one side getting added to. From this point on its just a matter of feeding your worms with kitchen waste (see below for feeding tips) and checking the bottom tray for worm juice. Once worm juice production has begun, you can begin feeding your plants. A ratio of roughly 10 parts water to 1 parts worm juice is a good ratio to stick too, but for heavy feeders like cauliflowers and leeks I go 5 parts water to 1 part worm juice.
Worm juice is sometimes nicknamed called liquid gold for good reason – it is one of the best overall sources of friendly microbes and bacteria that you can put into your soil, helping with overall structure and soil health, and it is high in nitrogen as well as a wide range of minerals and nutrients.
The picture below shows a door on the side of the bath frame with a latch to house the worm juice tray and to keep the whole system rodent proof. We just pull the tray out when we want to use some of the nutrient rich worm juice.
The Washing Machine Worm Farm
This is a much simpler setup than the Bathtub farm. Brett took the insides out of our old washing machine, leaving us with a shell and a rainproof lid. He cut the bottom off and replaced it with gauze for drainage, then he built a low stand to sit the whole thing on. This worm farm is situated around the back of the seedling house, so after making a bed out of straw and adding the worms, I began using it just to put my spent pot plants and chopped up garden waste from the seedling house into, along with lawn clippings every now and then. But now that there is a hefty worm population to feed, I put some of my kitchen waste in here too, alternating between putting it in here and the bath.
Because the purpose of this worm farm was mainly to compost large garden waste such as spent tomato plants and the like, we haven't been utilising it the best we could, and presently the worm juice just drains out of the bottom and onto the grass. But a system like this on the edge of a garden bed would be ideal, because the juice could then run into the garden and feed the soil and the plants growing in it.
Feeding your Worms
You can feed the worms anything that is organic and has been living, such as food scraps, garden waste (cut up small), animal or human hair, old leather, wool, straw, fish waste, seaweed, grass clippings, and manure, but there are a few exceptions to that rule...
Don't add:
raw or cooked meats, dairy products, large amounts of cooked foods
oil or fat
too many citrus or onion skins
dog, pig, cat or human manure
wood ash
It is important to gradually feed your worms in the beginning, taking notice of how fast your family of wriggly things is growing and how fast they are eating their food. As the amount of worms increase, you can begin feeding them more. Also take notice of the overall worm farm health and try to use your intuition. If the farm seems too wet, you will need to look at your drainage, while if it is too dry you may need to wet the top layer of cardboard or sacks. If you find you haven't added anything other than food scraps to the farm for awhile, give the worms a treat by putting in a bit of horse manure if you have it, or maybe some grass clippings. You can add a sprinkle of lime too if you think your worm farm is too acidic, but keep in mind that tiger worms are happy in quite an acidic environment.
Like anything, observation is key, and the more you get to understand your worm farm the more in touch with potential problems you will be. Generally speaking they are relatively easy to manage, and with the benefit of never ending free fertiliser, once you have a functioning worm farm you will be wondering how your garden ever got by without one. Happy farming!
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