Getting a wriggle on

Put your worm farms where the worms are happiest, writes Ben Elms, aka Dr Compost.

Feed each worm farm in turn over several days. Photo: Zac Edwards
Feed each worm farm in turn over several days. Photo: Zac Edwards

Owning a worm farm is one of those composting methods that is either a love, love experience or a worm massacre in which thousands of worms died at your hands.

The key causes of these worm Armageddons in the South are gross over-feeding the poor worms and the wild temperature variations that our worm farms experience.

Overfeeding in most worm farms is due to the confined space and the assumption that the population of worms can cope with whatever quantity of food we throw at them. Keeping an eye on how much food they are consuming is key to success, particularly in those first four months of setting up a new worm farm.

Hold back on feeding them if need be as the worm farm gradually grows in vigour over these early months.

Worms slow right down when the temperature drops below 10degC.

Looking at our autumn, winter and spring seasons, we may be getting close to half the year when average temperatures struggle to get above that. So then we have a double whammy of low temperatures causing slower food consumption, leading to a not-so-lovely pile of anaerobic, smelly food mush and a worm dystopia.

Clever placing of worm farms on the north-facing side of houses, under the roof eaves, in the tunnel/glass house (only over winter), or even in the laundry, are possible mediation options to keep temperatures up.

Or you could just forget the worm farm and chuck your worms into the cold compost heap. All that mass will keep them warmer over the winter months and they will happily move between your compost piles or bins following the food.

Over the past few years we have started to see a few worm "tube'' products on the market, ranging from five-inch drainage pipes to degradable cardboard tubes. The tube is dug into the ground, worms are added, then food scraps are applied.

Here at Dr Compost HQ we've been experimenting along these lines for many years, using recyclable and/or reusable materials where possible. We went bigger than the commercial products available, trialling old chimney flues and builders' buckets. Our thinking with worm farms is bigger can be better.

The temperature in the soil just a few inches under our feet stays pretty constant all year round. In the high heat of summer, when your worm farms might be overheating in full sun, or in the depths of winter, when it's the 10th day in a row when the high has been a whopping 5degC, you can see why finding a stable temperature for your worm farm would be desirable.

With these "in-ground'' worm farms, we can expect temperatures between 12degC to 15degC all year round. This isn't near our optimum 27degC, but it is going to be enough for our less intensive "in-ground'' worm farm approach.

I've been playing with the concept of having multiple in-ground worm farms, e.g., three to four in-ground worm farms (each in a 20-litre bucket) for a family of four.

What are the advantages of this system of composting?

The key is it's aimed at busy folks. Once set up (which takes an hour or two), all you have to do is put your food scraps in and let the worms do the work for you.

In-ground worm farms, dug snugly into the garden bed.  PHOTO: BEN ELMS
In-ground worm farms, dug snugly into the garden bed. PHOTO: BEN ELMS

How to

1. Grab three high quality 20 litre plastic buckets with lids. Look for buckets made from "high density polythene'', which reads as "HDPE 2'' on the bottom, to ensure a long stable life.

2. With a large drill bit (minimum 10mm, max 30mm) drill holes all over the bins. Leave the lid untouched. The smaller the drill bit, the easier it is.

3. Using a much smaller drill bit, drill some smaller "breather holes'' just below the top rim of the bucket to allow oxygen in. The holes should be too small for worms to wiggle their way out or to allow mice in to set up home in your bucket.

4. Decide where to put your "in-ground'' worm farms, at least 30cm apart. If you have raised garden beds, they can sit in the middle of them. A raised garden berm, or higher ground in the garden would suit too. They can be scattered around the garden but steer clear of heavy irrigation zones and areas that have the potential to flood eg with a high water table. If digging into a clay or boggy ground pan, find a drier place with lighter soil around the worm farm.

Drill holes all over the bucket. Photo: supplied
Drill holes all over the bucket. Photo: supplied

5. Dig a hole for each bin and place it in the hole. Remember to leave the lip of the bin above the soil with the air holes visible. If in a raised bed, take into account short term soil building efforts and mulch that may raise the soil level.

6. Time to make some worm bedding. Shred and soak five large handfuls of cardboard and place in the bottom of each in-ground worm farm.

7. Grab some tiger worms (Eisenia foetida). They are true compost worms that can munch their own body weight in food scraps every day. The more you start with the better. One to two kilos evenly split between three or four farms will give you a great start.

8. Time to start feeding. First up, feed all the worm farms with some food scraps that you've saved up over three or four days.

9. Now it's time to get into a routine. Take turns feeding each bin. Monday the red bin, Wednesday the orange bin, Friday the green bin, and so on.

10. Once the bin is completely full, get a small spade and dig out the top layer of food and vermicast. Put to the side on some newspaper. Empty the bucket of the nutrient and biologically rich vermicast. Store it or use it where desired around the garden. Replace the top layer into the bottom of the worm farm and off you go again.

Worms slow right down when the temperature drops below 10degC. Photo: Getty Images
Worms slow right down when the temperature drops below 10degC. Photo: Getty Images

Top tips 

• The smaller you chop up those food scraps, the quicker your worms can start munching.

• Avoid feeding them mouldy bread, oils and dairy.

• Check you're not over-feeding them. If you've got a bigger household and loads of food scraps, add another worm farm or two into the system.

• Plant veges close by and they will benefit from the increased fertility in the vicinity of the worm farm.

• Beware of big trees close by. They might get nosy with their roots

• Sprinkle a little lime in the worm farm once a month.

• If it's getting smelly, you're over-feeding for the size of the worm population. Mix some shredded cardboard into the top layer and don't feed them for a couple of weeks. Reassess your system. Do you need another worm farm in the line up? Was it a holiday food scrap glut?

• If rodents become a problem, set some traps in and around the worm farm. Then pop the dead rodent in the worm farm for the worms to munch on.

• Pop a brick on each lid for ease of use. You don't have to seal the lid each time and it won't blow away.

• During a hard, cold snap or generally harsh winter, cover the lids with some straw or old hessian sacks. Anything to stop the cold permeating down.

• You can get some old sacking or an old tea towel, dampen it and put it directly over the food scraps to keep those worms a little cosier.

• Tiger worms can be couriered from Wormworx in Cromwell: (03) 445-0263 or 021132-2964


Wanaka Workshops (6-8pm at the St John room, 4 Link Way)

• Winter gardening workshop: Wednesday March 14

• Easy ways to compost workshop: Wednesday March 21

The Dr Compost project is funded by QLDC and delivered by Wastebusters to reduce organic waste going to landfill. Ben Elms will be running free workshops in Wanaka next week and will be at the Wanaka A&P show this weekend.

Add a Comment