Everything You Need To Know About Worm Farm Composting

Composting is one of the most efficient and eco-friendly methods of disposing of biodegradable kitchen scraps, but it can take time. Adopting worm farming as your chosen method of composting is a simple, accessible way of speeding up the process, easily transforming your vegetable peelings into rich compost and homemade fertilizer. 

Why choose Vermicomposting?

Vermicomposting, otherwise known as worm composting or worm farming in a worm bin or wormery, is a quicker method than traditional composting to create rich compost and homemade fertilizer from kitchen scraps. It’s a great option if you’re trying to cut down on kitchen waste, if you live somewhere with irregular waste collection, you grow your own fruit and vegetables (or you know someone who does who will be very pleased with a gift of homemade compost and fertilizer) or if you’re simply too time poor to explore other waste cutting kitchen measures such as making homemade stocks or ‘potato chips’ from vegetable peelings. 

While you should do your best to keep the worms living in your worm farm happy, they can easily put up with a couple of weeks of neglect, so you won’t have to worry about your worm farm if you want to go on holiday, or if you’re experiencing a particularly busy work week. 

Choosing the right worm farm composter for you.

Do you have a lot of space to start a worm farm, or just a small fire escape or patio? Are you planning on starting your worm farm indoors? Are you a couple, living alone, or part of a big family generating masses of kitchen scraps? All of these are important factors in choosing the right worm farm composter design for you.

Traditionally there are two common designs: single bucket or bin styles (these may or may not have a tap for harvesting worm fertilizer ‘tea’, they’re also less common in the US) or stackable bins or trays to help you harvest a large amount of compost in stages. For outdoor worm farming, you can also buy subterranean designs that you can sink into the ground to attract existing worms through holes into your composter. 

If you’re looking to worm farm indoors and you don’t have a basement don’t be put off: there are actually some pretty stylish options available! 

Can I build my own worm farm composter? 

Yes, of course! The United States Environmental Protection Agency has a great guide to safely building and maintaining your own indoor worm composting bin. The Spruce also has a great DIY for creating a slightly more attractive, stackable outdoor worm farm setup. 

Where can I buy worms for composting?

Ideally, you’re looking for red wigglers (also known as tiger worms) or common earthworms. Search online for providers such as Uncle Jim’s Worm Farm (US), Gardeners Supply Company (US), Worms Down Under (AU), Wiggly Wigglers (UK), or Wormery (UK). 

It is also sometimes possible to order worms directly from your local U.S. Department of Agriculture extension office. 

Make sure the worms you are buying are not an invasive species such as Asian Jumping Worms, also known as Alabama or Georgia Jumpers which will inevitably make their way into your garden no matter how much care you take.

Where should I position my worm composter?

Very high or very low temperatures can possibly be fatal to your worms, so while you may be limited in your choice of worm farm by the space you have available for it, consider the natural climate where you live if you choose to worm farm outdoors. As a general rule choose a shady spot out of the direct sun, and move the bin inside when temperatures drop below freezing.

So I’ve got everything I need, how do I get started?

If you’ve purchased a worm farm composter rather than make your own, it should come with instructions specific to that particular design, but for all worm farms there are a few basic steps to keep in mind when starting out:

• Don’t feed your worms too much all at once. During the first few weeks only feed small amounts to your worms so they have a chance to process the compostables into a habitat. Be patient while the population - and therefore capacity - grows and bear in mind worms will eat a lot less in cooler weather. 
• Make sure you’ve added something for aeration. Some worm farms come with wood chips or cardboard to place at the bottom to start the worms off and provide aeration within the worm farm, but filling roughly 20% of the worm farm with shredded newspaper or cardboard will also do the trick.
• Make sure you feed your worms a varied diet.

What can I feed my worms?

As a general rule, if you’d compost it, the worms will love it, but with a few important exceptions:

Do compost:

• Vegetable peelings.
• Fruit peelings, including banana skins and melon rinds.
• Coffee grounds.
• Cardboard marked as compostable. 
• Newspaper.
• Compostable plastics, but only the thin bags rather than thicker, bio-degradable cups.

Don’t compost:

• Highly acidic foods such as citrus fruit, tomatoes, or pineapple.
• Chili peppers or the seeds from bell peppers.
• Anything with lots of seeds in, for example melon or squash innards.
• Meat, fish or dairy products. These will attract pests and can spread disease. 
• Processed foods or any foods containing oils.
• Plastic tea bags.
• Coffee filters.
• Plastic labels on fresh produce skins.
• Dog or cat feces. 

Egg shells are a controversial topic in worm composting. Some people argue you should not be adding them to the worm farm as the worms can’t actually ‘eat’ them, as in, they don’t break them down by digesting them, but other people argue they’re good for their worm farms as if you crush them into small pieces first the worms do actually consume them and the grit they provide aids digestion - they also help add calcium to your worm farm compost. They will also help keep the pH in the worm farm neutral; acidic conditions may prove fatal to your worms. Don’t put too many in, however, as you’ll start producing really gritty compost.

Tea bags compost really well and your worms will happily break them down for you, but some people prefer not to add these to their worm composter, or to tear them open and throw away the bags before composting as the bags can take a lot longer to break down than almost everything else you’re composting. This may lead to your compost still having pieces of teabag bag in it.

Onion skins are also a compostable item where when it comes to feeding them to your worms it is really up to how many onion scraps you generate. Onion skins, as well as the root of the bulb you’ll also be throwing away, are highly acidic, so while small amounts are fine to feed to the worms, larger amounts will upset the pH level inside the worm farm. 

For larger items, such as melon rinds, it will be a massive help to both your worms and the decomposition process if you chop your scraps into smaller pieces before composting. The same rule applies to compostable cardboard such as egg boxes: tear the card into small pieces first.

Do I need to add anything other than kitchen scraps to keep my worms happy?

Really, it depends on what condition your worm farm is in. The ideal pH for your worms is neutral so if you’re having problems (dying worms, worms that won’t eat anything, food decomposing before it can be eaten - though this could also be a sign that you’re overfeeding your worms) check the pH. If the pH is too high you can neutralize it by adding agricultural lime.

You also won’t want to let your worms get too wet, or too dry. If things are too damp (usually because you’re adding too many high moisture items) add more dry materials such as torn-up cards or shredded newspapers. Obviously, if your worms get too dry, add a little water with a spritzer bottle until things get back to normal.

Worm Fertilizer (‘Vermicompost Tea’)

If your worm farm has a tap, you’ll want to save screw top bottles to collect the light to deep brown (depending on the worm’s diet) run off which makes a fantastic all natural, zero-waste fertilizer that you can use on any crop you’d usually provide with a few extra nutrients. Tomato and aubergine plants, both from the nightshade family particularly love this fertilizer and it is a good alternative to seaweed fertilizer if your corn or squash plants are looking a little yellow because they’ve already eaten up all available nutrients in the soil. Houseplants will enjoy it in moderation, too.

If your worm farm does not have a tap for collecting this natural fertilizer, here are some great tips for how to make it yourself from what is already in your worm farm.

Using the compost from your worm farm.

How you harvest compost from your worm farm depends on which design you’ve chosen.

Single Bin Worm Farms

If your worm farm consists of one single compartment, for example, a lidded bin design, you have two choices. Either just go ahead and use the compost, and buy more worms to replenish the farm (they’ll be happy enough living out in your garden, just check the variety of worms you have purchased will not be a danger to the natural eco-system where you live), or you can manually sort the worms from the compost.

The easiest method to do this is to empty the worm farm into a large, shallow plastic bucket or wheelbarrow and, wearing plastic gloves, sort the live worms out of the compost by hand, returning them to the worm farm along with a few extra scraps for them to feed on now you’ve removed all their compost. Worms run from light, so by dumping the compost out you’re automatically sending the worms to the middle of the pile so you can start harvesting the compost from around the edges. 

Alternatively, you can simply remove just half the compost at a time so there will be some worms remaining to reproduce.

Tiered Worm Farms

Tiered worm farms, if you have space for them are much easier to remove the compost from as your compostables will be decomposing in removable layers. If you choose to remove the worms from a layer of compost before you use it, great! If not, you won’t have to worry about buying more worms if you just go ahead and use it as there will still be plenty of worms reproducing in your worm farm. 

Regardless of the method you choose, eventually, a bin will become overrun as the worms reproduce, so you will need to let some of your worms loose in the garden eventually!