How to set up a worm farm and keep it alive in summer

A worm farm is cheap to build and easy to kill

Worms will turn your kitchen scraps into the best soil conditioner you can get for nothing, and the whole thing runs itself once it is set up, so it is one of the few garden jobs where doing less is the right answer. The part nobody warns you about is that a worm farm in a Strathalbyn summer will cook if you put it in the wrong spot, and that is the bit this post spends the most time on, because everything else about worm farming is genuinely simple.

What you actually need

You can buy a purpose-built worm farm, and you can also stack a couple of 20 litre buckets with lids and be running by the weekend, which is what most people I talk to end up doing. Drill a grid of 6mm holes in the base of the top bucket so the liquid drains into the one underneath, punch a few air holes near the rim, and that is the farm built.

• Two buckets with lids. The top one holds the worms and the bedding, the bottom one catches the liquid.
• Compost worms. Garden earthworms will not do this job. You want red wrigglers, which get sold as tiger worms as well, and a handful begged off anybody in town who already has a farm going will multiply up on their own.
• Bedding. Shredded newspaper, torn cardboard or aged compost, wetted until it feels like a wrung-out sponge.
• Scraps. Vegetable peelings, coffee grounds, crushed eggshells and used tea leaves.
• Deep shade. The south side of the house or under a dense tree, never a spot that gets afternoon sun.

The summer problem, and how to get around it

Compost worms are comfortable somewhere between about 15 and 25 degrees, they get sluggish above 30, and a closed plastic bin sitting in the sun on a 40 degree day will get a long way past that, which is how most farms around here die in their first January. So the spot matters more than the farm does. Put it in permanent shade rather than shade that moves, keep the bedding damp because wet bedding buffers the heat swing, and on the really savage days lay a wet towel over the lid or sit a frozen 2 litre bottle of water on top of the bedding. If you are going away in the middle of summer, feed them lightly, soak the bedding and move the whole thing somewhere indoors like a laundry or a shed floor.

Feeding, and what to leave out

Start with a small handful of scraps and wait until it has nearly gone before you add more, because overfeeding is the single commonest mistake and it is what makes a farm smell. Always bury the food under the bedding rather than leaving it on top, which keeps the fruit flies out of it.

Leave out meat, dairy and anything oily, since those go rancid and attract rats. Go easy on citrus and onion, which are acidic enough in quantity to drive the worms to the far corner. Bread and heavily processed food will grow mould before the worms get to it, so it is not worth putting in.

Using what comes out

After a few months the top bucket fills with dark crumbly castings, and you can dig those straight into a bed or blend a couple of handfuls through potting mix when you are planting up a pot. The liquid in the bottom bucket is not the same thing as compost tea, whatever the internet says, so treat it as a mild tonic rather than a fertiliser, dilute it down to the colour of weak tea and water it around the base of plants rather than over the leaves.

When it goes wrong

• It smells. You are feeding it faster than the worms can eat. Stop feeding for a fortnight and add a good handful of dry shredded paper.
• Fruit flies. Food is sitting exposed. Bury it and put a square of damp newspaper over the whole surface.
• Worms climbing the walls. Usually too wet or too acidic. Add dry bedding, and a sprinkle of crushed eggshell will bring the pH back up.
• Everything has died. Nine times out of ten it got hot. Move it, start again, and do not take it personally.

Shop related products

• Plastic Bucket with Lid 5L. The small one is handy for carrying and diluting the liquid.
• Brunnings Peat Moss 5L. Good bedding material if you have run out of cardboard.
• Brunnings Seed Raising Mix 5L. Blend a little of your finished castings through it before you sow.
• Brunnings Ultimate Garden Soil 30L. For the beds the castings are going into.

Did you know we also stock 10 litre and 20 litre buckets with lids, bagged compost and worm juice in the garden centre, and those are not all on the website, so give us a ring on (08) 8536 4333 to check what is on the shelf. We do not sell compost worms, so that part is a matter of asking around town.

More from the garden centre

The bedding and the beds it all ends up in come out of the garden centre, and if you want a hand working out where to put the farm, come in and describe your backyard to us.

Keep reading

• How to compost kitchen scraps for a veggie garden
• Soil amendments, and which one your garden actually needs
• 5 ways to make a vegetable garden more sustainable

Mine lives in the deep shade on the south side, because I'm not to be trusted with one out in the open.

Candeece