A wicking bed is an excellent technique for growing things in environments where water is scarce. It’s got two main parts: the bottom half is a contained reservoir filled with gravel and water and the top half is filled with soil, mulch and plants. By periodic flooding of the deeper half of the bed, mature plant roots get a big drink. And because it’s contained, that water gets a chance to ‘wick’ upwards into the soil, hydrating the soil of the bed and the smaller roots within.
Pretty simple, really, but amazingly effective, very water efficient and ripe for endless variation.
Below is a photo essay outlining the process of creating a wicking bed using everyday tools and materials, which took 5 people about 4 leisurely hours to make. It features the efforts of our awesome PDC students in Alice Springs earlier this year, led by Nick Ritar who also designed this particular wicking bed system..
The first step is to create the reservoir which will hold the gravel and the water. This bed shape and size is based on the footprint of a watertank, a strip of which we’d found to use for the sides of the bed. Make the reservoir around 30cm deep, regardless of the size or shape of your bed.
To make a ‘closed wicking bed’ like this one, you want the reservoir to retain its water for as long as possible. We used builders plastic to line the reservoir.
Here is the water pipe that will deliver the water to the reservoir. The line of holes will be positioned facing the bottom, so that plant roots do not enter the pipe. The water pipe sits on three chocks to create a space between the holes and the ground, so the water can get out of the pipe and fill the reservoir. A vertical section will be added to the water pipe via the elbow at bottom left. The pipe is closed at the other end.
The reservoir is now filled up with gravel, covering the water pipe’s horizontal section. The gravel in a wicking bed reservoir is there to provide a structure for the soil to sit on top of while coming into contact with the water below.
The next step is to put the walls for the raised part of the bed on top of the reservoir. Where the reservoir ends and the bed begins, it is crucial to have an overflow. This means that, if the reservoir over-fills, the water has an escape point before it waterlogs the soil of the bed (and kills all the plants within).
In our design we created a simple overflow by raising the iron for the bed surround on pieces of clay pipe, which created a gap of about 3cm between the plastic and the bed surround above. The gravel was then raked over this gap so that soil will not escape in the event of overflow.
Now, if the reservoir over-fills, the surplus water will seep out of the bed at this overflow point and into the surrounding garden, saving the plants in our wicking bed.
And now for some soil, to a depth of about 30cm. You can see the hose going into the vertical section of the waterpipe (with a paver on top of it), filling up the reservoir for the first time. The plastic surrounding the bed will be covered with gravel and provide a weed-free barrier around the bed which doubles as a path. And also won’t turn into a muddy swamp when the bed overflows.
And for a passive fertiliser system – an in-garden worm farm! The worm juice and castings from this small system will leach out into the bed through the holes in the bottom of this box, fertilising the plants. A small proportion of worm juice may make its way down to the reservoir and mix with the water, further enhancing the biological relationships that will keep this bed’s soil humming.
A small but important task to make this bed serviceable – making a top rim out of old hosepipe which fits over the sharp edge of the corrugated iron that the bed surround is made from. Otherwise planting and harvesting in this bed could be a painful business.
Topsoil all in, a heavy mulch of pea straw is applied to keep the moisture in the soil where we want it. The small square in the bed is the lid of the waterpipe, and the larger rectangle is the lid of the in-garden worm box.
The inlet of the waterpipe serves two functions – firstly, you can fill the reservoir of your wicking bed – by bucket, hose or other water source. Secondly, this inlet hole allows you to see the level of water in the reservoir below, and so to accurately gauge whether your wicking bed needs more water added. A lid is a good idea to prevent evaporation and to keep your waterpipe clear of leaves, mosquito larvae and any other visitors you might not want in your system.
And there you have it – one completed wicking bed (with in-garden wormfarm)! The bed is now ready for planting a bunch of water-loving vegies which would be otherwise hard to grow in the dry climate that is Alice Springs. The property owner has promised us photos in due course on how the wicking bed vegies go, so we shall report back. But isn’t it a brilliant system? We ‘re in love with its efficiency and simplicity. Thanks, team!
43 Comments
I am considering putting in a wicking bed system and am concerned about the plastic sheet leaching chemicals into the water.
Is this an issue and are there any alternatives?
Cheers
hi catherine kingshott! its nicky warner here!!!
we are making a wicking bed all the way in alice springs! its a lot of work! will tell you how it goes
miss you !!!
I also am planning to put in some wicking beds and have the same concerm as Catherine, with the plastic leaching chemical from the plastic.
I also am wondering what stops the soil from mixing with the gravel. Can one use shade cloth to separate the gravel and soil as I’ve seen elsewhere?
In rain gardens like this a geotextile fabric is usually used to stop the soil moving down into the gravel layer to stop clogging.
Just wondering how you incorporate an overflow system for heavy rain events to stop water logging and root rot?
…Russ
Hi Russ,
Yep, the overflow is very important – look at the 7th image down and text above image: “In our design we created a simple overflow by raising the iron for the bed surround on pieces of clay pipe, which created a gap of about 3cm between the plastic and the bed surround above. The gravel was then raked over this gap so that soil will not escape in the event of overflow. Now, if the reservoir over-fills, the surplus water will seep out of the bed at this overflow point and into the surrounding garden, saving the plants in our wicking bed.” Best, kirsten.
… I missed the first time reading. You put the raised bed above the gravel bed for overflow.
…to pick up russ’ other question – in this design no geotextile to stop the soil clogging up the gravel?
any reason for that?
brilliant tutorial kirsten!
xLucas
Hey Luca – um, no real reason – we didn’t think about it at the time… it might be well worth the addition?
goodo!
i’m talking to my mum in perth about converting her backyard concrete fishpond (1m wide by 3.5 metres long by 80cm deep) into a wicking bed for vegies. we were debating the “geotextile or not” thing.
in terms of her getting fully behind it, it’d be great to be able to show her some clear explanation of how “wicking” (the capillary action thing) actually occurs.
in the absence of finding something really conclusive on the web so far, she’s agreed to try a mini-experiment of the whole process in a 10 litre bucket before committing her fishpond…
oh wow – have you considered an aquaponics system instead? if you’ve already got the pond…and there are multiple good aquaponics crews in perth… sorry to complicate things…
i think aquaponics is a step too far for mum. she seemed pretty pleased to get rid of the pond, its koi carp and the pumps. vegie patch first!
What a great article. I have seen in other sites the use of pea gravel for the water storage area, but it appears the poorly sorted gravel you use would be better at wicking water up to the soil. Would it make sense to have ridges and valleys in the gravel, cover with landscape fabric, then apply the soil so that parts of the soil in the valleys are saturated, allowing for better wicking effect? Especially if the rocks in the water storage area do not wick water well.
Hi, Thanks for the article. The issue with the plastic has been solved by some people by using bentonite clay for lining the reservoir.A natural volcanic clay, many kitty litters are 100% bentonite clay.It contains beneficial minerals in fact. You mix it into the top few inches of soil of your reservoir pit. Its got to be damp soil . Then you pound it to create a sealing layer. Have heard it is working for some. I did a several miniature pits but couldnt make them hold water for long. In one experimental pit I used clay from the back yard. It worked better than the bentonite.
Permacultureglobal.com has a few good articles on wicking beds. Mine is there with photos of the FANTASTIC results we got.
Cheers Bee – great tips. BTW we have a new favourite Wicking Beds article, by Rob Avis. Have a look at it here: http://www.energybulletin.net/stories/2011-05-31/bottom-diy-guide-wicking-beds
If the pipe is large enough – put a ping pong ball in it for easy visual reference of the water level.
nice one…
Very helpful article, thanks. I also want to construct circular wicking beds and this is the only website I’ve found demonstrating that. I’ve been wondering about the pipes in the reservoir. I thought it might be necessary to construct an x-shape (with 3 ends blocked off) to make sure it’s evenly distributed around the bed. But perhaps that would be overkill. I’d like to know if the owner of this wicking bed has any feedback about the success of the design? Do plants situated on the outer sections of the bed do as well as plants closer to the distribution pipe?
I’m also really interested to discover if there’s a more natural alternative to the black plastic. I might experiement with the bentonite suggestion, but I feel like there’s room for some more innovation with this aspect of the construction. I suspect a natural alternative may not last as long as the plastic, but I’m keen to investigate.
Thanks again for publishing such great information on your website.
Kate
Hi Kate, no we didn’t find that there was much difference in moisture distribution when using gravel… if you were using a finer medium that wouldn’t necessarily distribute the water so well this might be the case though?
I think I have found a viable alternative to PVC: EPDM.
Ethylene propylene diene (EPDM) type rubber is recommended by the Danish Environmental Protection Authority as an alternative to PVC.
EPDM is reusable, recyclable, and has better environmental impact profile than PVC. It is available in custom cut sizes as pond liner for water gardens at many garden centres and is available online at most pond supply places.
Here is an example of an online retailer selling EPDM lining:
http://creativepumps.com.au/zpumps/pond_liner/clearpond_epdm_liner/ozliner_epdm_liner.htm
Andrew
Interesting info, Andrew! Thanks!
Pond liner is more durable and since ponds support plants and fish may be more eco conscious.
Good point, Darrell – should look into that one…
Thanks for showing your design. I’ve learned that placing used carpet beneath the EPDM liner (also repurposed from a pond deconstruction) serves to protect the liner from punctures that occur with wear and tear over time. Having an impervious liner last a long time is essential to avoid having to start over.
I’m in the process of designing a seasonal creek bed and bog using the wicking system and incorporating a flow system that can be diverted to runoff during our infrequent rains in Austin. We’ll plant veggies and ornamentals along both sides of the ”creek” to take advantage of the trough. We hope to achieve a very natural appearance in the front of the house. I’ll be taking photos along the way.
Regarding the soil mixing with the gravel without some form of barrier question, it’s not a problem. Once the soil is sitting on top of the gravel it doesn’t mix for reasons I don’t fully understand. But, I’ve dug up plenty of old aggie drains (up to 100 years old), and the gravel is still sitting there beneath/surrounding the pipe with the soil sitting on top. One of nature’s counter-intuitive surprises. I suspect it could be a density thing…I dig the soil in my garden beds twice a year, and without fail the heavier clay is back down the bottom regardless of whether I left it on the top when I dug it over.
We are looking at building 2 wicking beds for vegies and herbs in above ground iron tanks. There are 2 things that we need some suggestions for…
The first issue, the tanks are 90cm high and so we need some way to fill up the bottom 30-40cm underneath the water reservoir and not sure of the best way to do this…
The other question, we have a heap of yellow brickie’s sand left over from the paving and were wondering if this is ok to use as a medium for the water reservoir or is the ‘yellowness’ a dye that would not be good if it gets into the vegies…
Any ideas/suggestions would be much appreciated!!! Thanks
Hi Melanie, yes you’ll have to waterproof the reservoir layer… with plastic or similar. Re the sand, that yellow color would likely be an oxide of some sort, so not too big a deal I don’t think (but ring the supplier and check if you can?) – good luck!
Queries about using a cloth over the stones and pipe to prevent soil mixing in, i just used old polyester curtains, the ones that have a very tight and very fine weave and they’ll need to be a man made fibre (polyester) so they dont biodegrade
i think the material is a chiffon or something similar…..
I also use this material on my seedlings….it keeps out vermon,snails, possums and lets in the rain and sun! You can gets heaps of it at the Op shop!
What is the ideal size of gravel for a wicking bed? Can one use 3/8″ gravel or is this too fine?
Cheers guys…this is a really great series of instructions that will enable me to plot all of this in AutoCad and share it with my lecturer
I have made six different wicking beds.one was in ground as in the above article.and the rest above ground.instead of gravel I have used compost and in two beds biochar and rock dust was added to the compost. This was to a depth of 150mm above this I added good garden soil to a depth of 300mm I. did use the compost worms for 1 yr but they got hungry, so I moved them to a farm closer to the house.They did very well in 2 milk containers with multiple holes and the top cut and hinged to act like a lid.2 of the beds are now 3 years old and work very well.my water consumption is 1/10 of that in conventional vegetable beds and trials of corn and tomatoes showed vastly improved yields .it also keeps the rabbits out of the veggies.I use builders plastic ,agricultural pipe covered in weed mat,shade cloth or geotextile (in 3 different beds) and all worked well, I prefer geocloth .
For large rings(using 5 m diameter rain water tanks) I have made intersecting crossed ag pipe as I was concerned of the distance the water had to move across the compost.
I also used old carpet and 10 layers of newspaper to stop stones perforating the plastic.I line the tanks to a depth of 15 cm with double layers of plastic. Put in the ag pipe covered in geocloth and then fill with water to 15 cm depth I then cut off the plastic at that height before filling with compost.I have good overflow ,and know I have no holes that way.
When away I have worked out the time it takes to fill to 15 cm and have a automatic timer set to water once a week.
For large cut off tanks I lay boards across the rim for planting and weeding .
For smaller tanks I put in 2 logs in end up with soft cushioning on the base. I can step on them to get to the centre of the rings without compacting the soil or risking perforating the plastic.
I think the wicking beds are a great idea
Wonderful Ideas from across the globe. I have a slanted yard (in more directions than one). We are putting in a tiered garden next year and I thought it would be useful to incorporate a system like this into it. We will be using landscape boards to build up from the ground with minimal digging. I think it’s possible to then line each section of the garden with plastic and place the watering pipe in each bed. Thanks for the ideas!
I have made a few self watering vegetable planters from polystyrene boxes, and I have had some success, mostly with salad greens. I used potting mix and supplemented with organic fertilizer pellets. I now want to make more permanent wicking beds like yours, and I wondered if you could update us as to what changes you would make, and whether you have had any problems with the soil getting too compacted? Thanks heaps.
Hi Christine, our wicking bed is 18 months old and going really well. Its a level pit lined with plastic , filled with wood chunks and gravel with slotted fill pipe buried in the aggregate. All this is covered with shade cloth, and a sleeper box placed over top and filled with damp soil and compost. Would and are about to do it again exactly the same.You can see how it was done in photos on http://www.merribeeorganicfarm.net.au . More info is in Bees Blog on home page.Good luck.
Thanks for that reply. I had a look at your site and the wicking beds look a treat. I wish I was closer so I could come for a look. What have you found that you can’t grow in them? Do some vegetables need more depth for their roots?
No, everything we ‘ve tried has gone well. It is pretty deep soil …..about 400 mm, and I grew a parsnip in there that was as long as that and perfect. As I say, only trouble with them is you have to water so infrequently that you might forget to.
Very impressed about the parsnips. I have heard that they are not the easiest thing to grow. One last question. Did you import soil for the beds or use local stuff and feed it up?
I make my own compost Christine and just mixed it with the topsoil removed from the pit.
Hi Milkwood crew, we’ve recently taken the idea of the wicking bed and made it mobile based on Nick’s ideas at last October’s Mudgee PDC of using an IBC container. The only difference is that we’ve built them purely for native plants as we are a conservation not-for-profit. It means that we can build the gardens in one location with one group of people and deliver it to another group of people… a great way to connect people with money and time to those in need of gardens like schools with no grassed area!
The first one was close to 300kg so too heavy to be practical but for the second one we used waste polystyrene instead of the gravel. Seems to work well and easily halves the weight so 4 people can lift it on and off the back of a ute.
We recently built one that will end up in a Sydney school with the staff of one of our corporate partners – it was a great way to make it quick and easy for busy people to get their hands dirty. There are some photos here if you’re interested… http://www.bulldogs.com.au/photogallerydisplay/Greening-Australia-Garden/3813
Well done! Awesome! You could consider vermiculite for the veggie versions also (if you go that way)?
you may want to put neem oil in the watering to stop mosquitos – or are they not a problem …. I’m wondering does neem oil kill earth worms and other insects and microbes ?
Loving this idea. Did you use any particular soil mix? Our soil does not look as good as yours. Should we mix it with anything to loosen it up?
Thanks for a great article, we’ve been using a smaller bought version which works well. This is how we can build a much larger one.
Fantastic tutorial. I’d like to know how this bed’s working out a few years on, particularly the worm bin. Do you have any recent photos?
14 Trackbacks
[...] is basically the same idea as a worm tower (with holes in the bottom only), and was installed in a wicking bed we made in Alice [...]
[...] Would we use it again? Well, we’ve been trying very hard to figure out how to do a large wicking bed system for our Milkwood kitchen garden. We definitely want to use wicking beds, but we definitely want to [...]
[...] wicking box functions the same way as a wicking bed (see how to make a wicking bed for the full [...]
[...] Permaculture has pioneered an in-ground wicking bed using builder’s plastic and a round galvanized culvert ring. We have also seen people use stock watering [...]
[...] How to make a Wicking Bed Share this:MoreEmailDiggPrintLike this:LikeBe the first to like this post. This entry was written by milkwoodkirsten, posted on November 9, 2011 at 9:59 am, filed under farm and tagged food. Bookmark the permalink. Follow any comments here with the RSS feed for this post. Post a comment or leave a trackback: Trackback URL. « P-culture. Ya dig? [...]
[...] Permaculture has pioneered an in-ground wicking bed using builder’s plastic and a round galvanized culvert ring. We have also seen people use stock watering [...]
[...] this workshop, Monique will be hard at it in the coming weeks installing the innards of her bathtub wicking beds, and planting up her garden! She’ll also need to render the outside of the bags to protect [...]
[...] constructing your own raised bed and would like to know about this kind of system then I found this tutorial particularly useful. I will bring you more on this as it progresses but for now I eagerly await [...]
[...] by Erin B on October 2, 2012 As the weather warms up that inescapable itch to get out into my garden has well and truly set in. With glorious weather in Adelaide over the long weekend we got to work on the bed I have been planning for the front garden that will be home to this years tomato crop. As outlined in my previous spring gardening post, I am keen to experiment with the construction of a wicking bed to make watering less of a hassle. A wicking bed is effectively a big self-watering pot, with a reservoir built-in underneath the bed that delivers water to the root zone via absorption or ‘wicking’: A wicking bed is an excellent technique for growing things in environments where water is scarce. It has got two main parts: the bottom half is a contained reservoir filled with gravel and water and the top half is filled with soil, mulch and plants. By periodic flooding of the deeper half of the bed, mature plant roots get a big drink. And because it’s contained, that water gets a chance to ‘wick’ upwards into the soil, hydrating the soil of the bed and the smaller roots within. – Milkwood Permaculture [...]
[...] [...]
[...] Permaculture has pioneered an in-ground wicking bed using builder’s plastic and a round galvanized culvert ring. We have also seen people use stock watering [...]
[...] Milkwood Farm on how to make a wicking bed; [...]
[...] Permaculture has pioneered an in-ground wicking bed using builder’s plastic and a round galvanized culvert ring. We have also seen people use stock watering [...]
[...] http://milkwood.net/2010/05/11/how_to_make_a_wicking_bed/ [...]