Vermicompost is an excellent way to add a balanced nutrient boost to almost any garden at any scale. On the farm, I created my seeding and growing mix with vermicompost. However, this can be done on a small scale as well for a home garden or container gardening.
Christy Hansen has been vermicomposting on a small scale for several years. Here is her article for a method that works for her on a very small scale for her container gardens.
Construction
I made my worm bin out of a half size rubbermaid bin. In the top half of the bin, I drilled air holes approximately every three inches, using a quarter inch drill bit. If you make larger holes, fewer of them are needed. Some people cut one large hole in each end and cover them with a vent cover.
I then glued plastic window screen over the holes using E6000. This helps prevent worms and pests from moving in and out of the bin. This is primarily a measure to reduce the number of fruit flies and fungus gnats that mind their way in or out of your bin, which are common and annoying, but harmless pests.
Ideally you should also drill drainage holes in the bottom of your bin. I didn't do this as I don't have any sort of tray to catch the drainage, but without one I need to monitor the moisture levels in my worm bin more closely.
A full sized bin is better as it allows more room for bedding and air circulation. I used a half sized bin because that fit in my space better. For an easier start, it is fairly easy to find prebuilt vermiculture setups online.
Feeding
Worms need carbon rich foods and nitrogen rich foods in a fairly specific ratio that I have forgotten. Fortunately you don't actually have to worry about that ratio! This is because your carbon based food is the bedding that your worms live in! So long as you make sure your worms have enough bedding, and you're giving them nitrogen rich foods (fruit and vegetable scraps) about as fast as they eat them, your worms will be happy.
Bedding
Just about any nitrogen poor plant based material will work for worm bedding, but there are a few things you want to avoid.
Good bedding materials include:
cardboard
newspaper
unbleached paper
coconut coir
egg cartons
fallen leaves
dead grass (in moderation)
If you don't have enough material to get started, I've found that worms particularly like crinkle cut paper. They're also fond of corrugated cardboard, as the layers create prebuilt tunnels for them. It's best to use a mix of different bedding types so that the worms have a variable environment to live in.
Try to avoid large amounts of bleached paper. You should also avoid excessive amounts of glue as the worms can't eat it, or any paper or cardboard with a shiny surface as that means it has a plastic coating, which the worms also can't eat.
Most dyes are fine for worms, but it may be wise to avoid materials with excessive amounts of dye
Worms need an environment that's about 80% water. In practice this means that their bedding should be wet all the way through but not drip if you squeeze it lightly. When adding new bedding I will soak the material in water for an hour or two, then let it drain out completely
Monitor your worm bin's moisture levels, if the bin starts to dry out mist the top or add wet foods, if it gets too wet you can open the lid or add dry bedding. Make sure water doesn't pool in the bottom of the container, as the worms can drown. If you have drainage holes this shouldn't be a problem, if you don't, you can put dry bedding in the bottom of the container when it starts to get too wet.
Your bedding should also be loose with plenty of space for air to move through it.
A healthy microbiome in your worm bin is important to help the worms digest their food. When first starting your bin, it's good to add a little bit of soil and/or a banana peel and let it sit for a week before adding your worms.
Food
I feed my worms about a pound of fruit and vegetable scraps weekly. make sure that they have eaten all the food you put in before you give them more! Worms can live for several weeks on just their bedding, so it is ok to miss a week occasionally.
Cut the food up into fairly small pieces so it is easier for the worms to eat it.
Good food:
most fruits and vegetables
coffee grounds (in moderation)
melons (these are their favorite)
broken up and cleaned egg shell (occasionally)
opened tea bags
Avoid:
Tomatoes
onions or garlic
any animal products
oils and salt
acidic fruits
large amounts of citrus
spicy foods
Other critters:
Worm bins like to have plenty of insect life in them! millipedes and pill bugs are helpful and harmless little critters in a worm bin. Millipedes may eat your worms. You will likely find some mites (tiny little insects) in your bin. Many species are harmless but some can attack your worms. if you notice excessive numbers of mites, or small red mites congregating around your worms, it may be time to intervene.
Visible mold in the bin probably means it's a little too wet, but isn't a big problem. Slime molds are harmless and are a fun additional pet.
Issues
flies: This is a big part of why my bin has screen over the holes. Fruit flies can be avoided by burying your food just under the surface, but if you get fungus gnats they may be impossible to get rid of them. I reduce the numbers by making it more difficult for them to get in and out of the bin. putting dry bedding on the top can also help.
smell. Your worm bin shouldn't smell. if it does you may be feeding too much or have anoxic conditions in your bin. make sure all the food is getting eaten and the bin isn't too wet. Stirring the bin occasionally can help keep moisture levels even throughout the bin and introduce oxygen. Don't do this too often though, as the worms don't like to be disturbed
Notes:
Worms like wet, dark conditions and don't like light or being disturbed.
a healthy microbiome is important
Slime molds are fun. mine didn't stick around though.
I also have millipedes. isopods would be fun
your worms will try to run away because they're stupid. Especially when you first add them or move them to fresh bedding. The happier they are, the fewer will try to run away.
Christy Hansen