How To Make A Bathtub Worm Farm In Eight Easy Steps
Step One:
Get your hands on an old bathtub.
Shouldn’t be too difficult as there seems to be plenty of them for sale. Now that house prices are high many people are choosing to renovate rather than building new. I bought this one on Trade Me for $11.50.
Step Two:
Make up a frame to support the bath.
Raising the bath tub means feeding and harvesting the worms and their castings can be done at a comfortable height. I chose to make a timber frame as the cast iron bath was heavy and I needed to feel relaxed that it was safe and not likely to topple over. If you don’t wish to go to this extent concrete blocks or railway sleepers would suffice.
Step Three:
Make grate to fit the bottom of the bath.
The purpose of this is to create a free draining environment for the worms and to allow for collection of the liquid fertiliser or “worm tea”.
Step Four:
Place netting over the wooden grate.
I used a staple gun to attach it to the timber so that it remains in the correct position. Small nails or tacks would work equally well.
Step Five:
Attach tap to bath waste pipe.
For a few dollars these components can be found in the plumbing department of most hardware stores. Fitting a tap to the base of the bath means that nothing is wasted and the rich black liquid that the worms produce can be used on your garden and house plants.
Step Six:
Line the bath with weed mat.
This matting needs to allow water to flow through it. Some are tightly woven and don’t have good drainage qualities therefore its important to use the right type. To keep the weed mat in place I used 50mm wide sellotape. For the tape to adhere well make sure the surface of the bath is clean and dry.
Step Seven:
Add bedding.
After shifting bedding and food from some smaller bins I introduced the tiger worms to their “new digs”, approximately 4000 of them.
Step Eight:
Cover the worm farm.
Lastly a lid or cover is necessary to keep out the light and to protect the worms from heavy rain and other unwelcome visitors. Worms are photophobic and unlike we humans prefer to be kept in the dark.
At the time of writing this post I hadn’t made any ventilation holes in the lid but will do that within the next few days. Once that has been done my first bathtub worm farm will be complete.
I enjoyed making the worm farm but will use an acrylic bath next time as this one was extremely heavy. That aside I’m sure my worms will relish their new accommodation and hopefully increase their numbers within the next few months.
Perhaps you’ve made a worm farm recently, if so any thoughts, suggestions or comments would be most welcome.
Post Script: Have made some minor changes to the farm as the worms were escaping into the lower area of the bath. With this fine tuning now complete all is working well again … you can check it out here.
This post has 34 comments
October 7th, 2009
WOW..very creative.. and an excellent idea!!!
Will you be leaving this tub out in winter? I had red wigglers last winter and they died in the tub. I had put it in my garage..very depressing to see them dead like that. It took me a while before I had courage to do worm composting again.
October 8th, 2009
Hi Lisa … yes I will leave them out over winter as we have a fairly temperate climate here in Auckland. Great to hear that you hung in there with your worms. Where in the world are you?
October 7th, 2009
Curious to know why you lined it with weed mat?..I just put coir straight into the bottom of my bath..I siliconed a bit of fine mesh over the drain hole,so I can catch the drips,and the worms don’t get out..the wet sloggy base of my can-o-worms gets lots of worms living in it,despite having a ‘drier warmer’ space in the 1st layer tray,so they don’t seem to have to much problem if it gets too wet.I’ve seen a few pix of bath worm farms,after I did mine, and they all have wood or gravel in the base,but I wonder if its really needed,as long as the liquid can drain?.
October 8th, 2009
Just wanted to make sure that the worm farm has good drainage over it’s whole area and chose weed mat as the best and easiest way to achieve this. Felt that if I limited drainage to just around the plug area there could be issues with it getting clogged up. Also wanted to ensure that the bath didn’t get too wet towards the bottom.
The weed mat has small perforations in it which allows excess moisture to continually drain away. By doing it this way I’ve created a cavity at the bottom of the bath for the collection of the worm tea which is drained off every few weeks.
Also having the weed mat makes it very easy to aerate the contents without the worry of material such as scoria etc getting mixed in.
For me this system works really well as the moisture level within in the bath remains constant. This has to be good for the worms. I just add food and lime and turn the contents from time to time. My tiger worms seem to agree as the are flourishing. Thanks for your comment and interest.
January 25th, 2010
Hi there
I’ve looked at other DIY instructions that have made ventilation holes in the sides of the bath using an angle grinder – is this necessary?
January 26th, 2010
I guess you could but I found it easier to create the ventilation holes in the plywood cover of the worm farm. Have drilled the holes towards the rear to prevent the rain getting in. This works OK and there’s no chance of them getting blocked up or the worms escaping. Drilled a grid of approx 60 x 5mm holes in each cover which allows plenty of air circulation. My bath tub farms are partially protected from the weather by the roof eave of the house. Hopes this helps.
January 30th, 2010
Hi Rodney,
Here at Carterton Preschool we have attempted your wonderful bath worm farm with help of parents and children – a great learning experience. We have the farm almost ready to go but just wondering as it is a new environment what to put in the base. Perhaps some old compost or peas straw then the scraps to get started.
We have made a lid which is slightly higher than the bath to alow ventilation but thought we might need carpet, on top of the worms, to ensure darkness what do you suggest?
We are keeping a photo record if you would like to see them.
Thanks for the inspiration.
Lynette
January 30th, 2010
Hi Lynette
What you’re suggesting should be fine. You can also use shredded paper and cardboard (avoid glossy printed) egg cartons, toilet roll inners and such like. Aged horse and cow manure also works well but may not be so suitable in a preschool situation.
Using old wool carpet works well as it blocks out the light and encourages the worms to feed on or near the surface where the food is placed. This also helps to prevent the food and bedding from drying out.
Welcome to world of worm farming, I’m sure the children “and others” will find it very rewarding.
I would love to see any photos you have.
Cheers ..
February 28th, 2011
Just browsing through and came upon your site, I have a worm farm in an old chest freezer, helps keep the little critters warm in the winter nights.I was interested to read about the use of carpet as a covering, I had been told that all NZ wool carpets made up until the mid 80′s were sprayed with LINDANE at manufacture, any body able to comment?
Rob
March 14th, 2010
This is a seriously nice design. Now that it’s up and running- how much waste can it handle a week?
March 14th, 2010
Hi Catherine … thanks for your comment. I have three of these and feed the worms approx 3 kilos a week per farm. This is mainly kitchen waste and excess or waste from the vegetable garden.
I visited Dublin back in 1978 during a month long holiday of Ireland. Had a very enjoyable holiday …it’s a magical place. Was living in Inverness, Scotland at the time.
March 16th, 2010
Yes, It’s a great place- and perfect for worms- no danger of them ever drying out- all that rain…
June 20th, 2010
Hello Rodney,
Came across your post when Googling for info about making a worm farm. Just a question about where to get the worms – where did you get your worms from? I have an old bathtub and thinking of turning it into a worm farm. I do regular composting and my compost bins have loads of worms – do you know would these worms work for a bathtub worm farm? I was thinking just to start the worm farm with some of this wormy compost. Do you think that would work – or would they be the wrong type of worms?
Thanks,
Aidan in Nelson
June 20th, 2010
Hi Aidan …
Assuming the worms in your compost heap are tiger worms and they probably are they will be just fine. Can distinguish them by the circular red and yellow rings along their body. Starting off you bin as you suggest will work OK … may take some time for worm numbers to build up however …say 6 months.
Tiger worms are readily available on the web … including this site. Trust this helps.
June 20th, 2010
Thanks Rodney. Can’t say I’ve noticed red and yellow rings but I’ll have to take a closer look. Do they exist normally in the ground? Or would it be more likely that the worms that make their way into a compost bin are just the standard earthworms?
June 21st, 2010
Yes tiger worms do naturally exist in surface layers that are rich in organic material and can often be found in aged compost piles. There are plenty of images of tiger worms on Google. Not likely to be earthworms in your bin as they are burrowers and exist at deeper levels within the soil.
July 4th, 2010
Hi Rodney,
I put my bathtub worm farm together today. I’ve posted a blog with some photos:
http://aidansgarden.wordpress.com/2010/07/03/my-no-cost-bathtub-worm-farm/
There is a closeup of the worms there, looks they match your description so I’m fairly confident they are the right ones. If you have any comments I’d welcome them on my blog post.
Thanks for your input.
Aidan
July 12th, 2010
Ho Rodney,
How long should it take until it produces some worm juice? I didn’t get anything out in the first week. I added some more scraps and leaves this weekend and watered it. Got a little liquid out but I think it was just a bit of excess water.
Cheers,
Aidan
July 12th, 2010
It will vary depending on the number of worms you have. My farms didn’t produce any sizable amounts of juice for several months and that was with approx 4000 worms.
July 13th, 2010
There has been about half a litre out since but it may be just the excess water. Do you add water to your tubs? if so, how much?
July 13th, 2010
May give them a light spray with the hose in summer if things dry out too much but otherwise I don’t add any water.
July 28th, 2010
Hi Rodney, I’m trying to start a wormfarm at the highschool which I go to. I wanted to know whether or not the wood you are using as the grate is treated? Also how much did everything cost? And one last question, where do you get the worms from? By the way I’m from Auckland.
Thanks.
July 28th, 2010
Wood I used was untreated and I’m aware it will break down with time. From memory all up it cost me approx $60-$65. If you Google compost worms you will find a number of suppliers. Hope this helps …
October 30th, 2010
Hi Rodney. I’m in Hamilton and have been acquiring things for my worm bath. Not set up yet.Have three bin working farms of my own and a Can O’Worms farm. All are pumping. Are going to follow your plan so will get back on that.
Renata
January 30th, 2011
Hi Rodney. Had my bath up and going for two months now. Emptied a kilo or so worms from my Can O’worms. Everything is going well. Just wanted to know how many worms can live comfortably in a bath ? Or how many would you recommend ?
January 31st, 2011
The worms you’ve added will probably double in number over the next six months or so. In each of my bath tub worm farms I imagine there are approx 4000/5000 worms and they seem to be happy … as far as I can tell. Keep them well fed and the rest should look after itself.
Thanks for feed back and good luck with those worms of yours … cheers.
March 13th, 2011
Hi Rodney,
I found you via your article in NZ Gardener borrowed from my daughter. I have had worm farms of the Warehouse Variety (square 2 bin) for a couple of years but only once managed to get juice flowing and then the medium and food was really soggy and not nice to use as compost . About Feb last year they all migrated to the bottom bin and drowned so over Easter I set up a new colony hoping to have juice flowing by mid winter. The worm colony has gone but still no juice. I use a mixture of pulp from juicing fruit/veges, kitchen scraps,cardboard and newspaper. The medium isn’t soggy but there is no juice. Do you have any tips please? Last month I removed all the worms by hand, slow job, and flushed water thru which gave me a supply of juice but now I guess it has set back the production again.
March 13th, 2011
By the way I live in Hamilton, so winter is a bit colder than Auckland – does that slow things up?
March 16th, 2011
The smaller worm farms don’t produce large amounts of juice. From past experience I’ve found it takes say 3 to 4 months for any flow to begin. Suggest you go easy on the fruit pulp etc as I suspect its all getting too wet and possibly too acidic.
I use a balance of greens and browns and avoid loading the farms up with any one type of material.
I find that activities do slow down some what during the winter.
Hope this helps …
April 19th, 2011
Hi Rodney.
Thanks for taking the trouble to explain your method and provide photographs. That is a very neat and tidy worm farm. Clearly it is not an offensive structure in the garden and could be used as a potting bench or similar.
For those who lack skills or motivation, please don’t be put off. I have successfully used a bath which is just mounted on an old steel frame from a desk. It is hidden inside a shade house for appearance and climatic reasons. I live in Adelaide and it gets ridiculously hot in Summer. The advantage of the bath is that the total volume is so great that it is not subject to wild temperature variation and I can attest to the worms thriving in all seasons.
I did not even think of the lining method you created. My drain hole is covered by a small piece of shade cloth and I have just loaded all the bedding and food in without liners or drainage media. I am sure your system is more effective but if any lazy types are reading this, you can get away without it.
I love reading about the experiences and success which others have with their worm farms. I don’t have anything unusual to offer except that I experimented with an old pair of Levis recently. I removed the copper and brass bits and threw them in. They were gone in about three months.
May 17th, 2011
Hi Rodney
I love your descriptive bath worm farm set-up. The only difference I made was to use blue-metal gravel for drainage instead of the wooden grate.
Gr8 to read all these bath worm farm experiences.I, like Rob (April 19,2011), love reading and researching worm farm methodology.Rob’s jeans experience proves that Levis are, indeed, made of cotton, even the stitching thread must have been cotton ‘cos the worms wouldn’t have turned up their prostomium for polyester!! Here in Perth, like Adelaide, Summers are extreme. My bath farm is in the garage and I’m able to maintain temps in the farm itself at around 23-27degs by leaving the lid off during the day and await the, hopefully,cooling late arvo southerly breeze. I feed mainly horse manure to the bath worms as I have a readily available source from stables nearby. I collect this and dredge it for around 3-4weeks before feeding to the worms – they are into it within a few hours – kids in a lolly shop couldn’t be happier!! I top the manure with a large qty of newspaper pulp (approx 6 newspapers which I’ve soaked in water over 5 days then shredded). This pulp retains moisture in the farm over a long period.I harvest half the farm’s worms from their castings every 3 months and replenish their bedding using my home-grown aged compost.
June 30th, 2011
Rodney,
I loved your idea and it so happened the neighbor had two tubs he was getting rid of. We so graciously took them off his hands. lol.
My question is this: I live in the south (aka land of many bugs). The tubs they are in now have ventilation holes and it seems they always get an infestation of flies or something no matter how deep I bury the food or how many layers of cardboard I wet and lay on top. I would like to cover the worms with a wood lid and then cut a couple inch square in it and put a layer of astroturf there. Do you think that would keep the bugs out but still let enough air in? Thanks
June 30th, 2011
I wouldn’t worry about the bugs as they won’t affect how your farm works. My worms farms have all sorts of creepy crawlies in them. You could use a fine mesh to cover the holes in the lid as this should stop the flies. I cover the bedding, food etc with an old piece of dampened carpet as this allow the air to get through and prevents things from drying out. Make sure you don’t feed meat, dairy or such like as this will attract flies. Don’t quite understand what you intend doing with the astroturf ?
July 25th, 2011
Rodney, thank you so much for your response. A fine mesh is a good Idea. The astroturf was an idea I thought of to use as an alternative to the carpet. Through my reading on worm bins I read that mold competes with the worms for food and that mold is a sign of the environment being too damp and hot. I thought the carpet might mold in the worm bin. I’m not sure if the information is accurate or not. Evidently it hasn’t posed a problem for your bins yet, so I imagine it wouldn’t be an issue?
Again, thanks for your reply, the bins are coming together quite nicely. Is there a place to send pictures when they are finished?