Wicking beds are a water-efficient gardening method that involves creating an underground reservoir to supply water to plants through wicking. The key aspects are: 1) Constructing raised beds with a waterproof liner and filling the bottom with rocks to create a reservoir, then adding soil on top for planting. 2) Water is supplied to the reservoir and wicks up through the soil to the plant roots, reducing evaporation and the need for frequent watering. 3) For optimal plant growth, the soil layer should be 300mm deep while the water reservoir can be deeper to allow longer between waterings, though benefits diminish beyond 300mm depth.

1. Constructing garden Wicking Beds –May / June 2009
"The wicking worm bed is a highly productive growing system which not only
produces more food from limited water, but also recycles waste organic material to
provide plant nutrient and capture carbon. The essence is to form an underground
reservoir of water or pond contained by a waterproof container or liner below the
surface of the soil. Plants are productive because they have a continuous supply of
water and nutrients." Colin Austin
We have extreme water restrictions here in Melbourne. All garden watering must be
done by hand-held hose, and only on two mornings of the week, so this method of
gardening offers a great solution. Water doesn't evaporate in the bottom of the
wicking bed–it 'wicks' up to the roots, and, the top soil will stay soft, under the mulch.
Now, we'll only need to water once a week in summer, and less during the rest of the
year.
The inventor of this system, Colin Austin has clips on YouTube, showing how to do
this in small plastic containers, for use in small spaces:
http://www.youtube.com/watch?v=80-dkv1Au-8&feature=channel_page
And here is his comprehensive and highly informative website:
http://www.waterright.com.au
Here is another good website, with easy to follow instructions.
http://www.easygrowvegetables.com/
NOTE: I wrote to Colin Austin to ask for advice on the best level for water and
drainage, and received a terrific reply, which I've posted (with permission) at the end.
(He explains that water will naturally wick up only 300mm.)
We built our wicking beds using a combination of suggested methods, as follows:
The sleepers, soil, mushroom compost, and rocks were delivered to the front of the
house, and carried by the two of us to the north garden, at the back of the house!
Still, even with the hard labour, we get great satisfaction from working in the garden–
and, like all passionate gardeners, we take deep pleasure in nurturing, 'knowing',
eating, and sharing our abundant harvests with our excellent neighbours.
Materials needed for two 5x1 meter beds (16 feet long), one of which was
terraced, so needed more sleepers:
23 red gum sleepers, each 3.5 meters (8 feet) long and 75 Ml (3 inches) thick. Red
gum timber (or similar) is much stronger than treated pine, which will poison the soil
and will rot on the ground anyway. The price is almost the same.
11 meter (36 feet) long (comes in roles 20 x 4 meter wide). We used black 200 um
plastic sheeting, and we now think it just isn't strong enough. Next time we'll look for
the orange industrial strength plastic, which would be much less sensitive to pointy
things cutting through it, and since it won't be visible above the ground the colour
won't matter. HINT: we found a hole in one role of plastic, and sealed it with pool
lining glue.)
10 meters (33 feet) 70% shade cloth (you can cut and overlap pieces.)
10 meters 65mm agi-pipe (33 feet) (perforated agricultural tubing) + plus 70mm pvc
pipe (one length cut in half for the two beds) w/ elbows for attaching to agi-pipe. (Buy
all three parts at one time,– to fit.)
NOTE: The garden bed gets watered from the top via this pvc pipe, creating an

2. underground stream which waters the plants from below, hence 'wicking'.
Soil, compost, and rocks (A square meter = approximately one metric ton):
1/2 sq. meter 7mm or 14 mm screening rocks (not river rocks)
1 sq. meter of organic soil
1 sq. meter mushroom compost (combined with our own organic vegetable compost)
Small bags of Blood & Bone, lime added to the soil from the old beds.
We plan on adding worms to the wicking beds next season, when the soil is fully wet.
NOTE: We purchased double this amount of soil and compost to spread around the
other in-ground garden beds, which we plan to convert also.
Step 1.
We removed the soil from our existing
5x3 meter garden bed and then leveled
and terraced the ground for the two new
beds, which must be completely level for
even water distribution. We put a layer of
soft-sifted soil on the bottom for
cushioning, and created a waterproof bed
with the 200um plastic sheeting (make
sure no sharp objects can cut into the
plastic sheeting).
Step 2.
We added the agi-pipe, str
length of the bed.

3. Step 3.
We covered the bottom of the bed to just
above the pipe with the screening rocks.
Step 4.
We connected PVC pipe to
using a common pvc "elbo
then we covered the rocks
shade cloth, to separate th
rocks and pipe.
Step 5.
Then we sifted the old garden soil into the
bed, removing stones, seeds, weeds and
roots.
(The above photo was taken from inside
the house).
This was backbreaking, tedious work,–
bending, and reaching out with a heavy
tray of soil, then shaking it to sift it out, so
we put new soil in the second bed. Easy!

4. Step 6.
We did it!
We sifted the old garden soil, and added
a generous mixture of our own organic
compost, mushroom compost, lime, and
blood & bone, –leaving a space at the top
for mulch.
Step 7.
We filled the top with a laye
sugarcane mulch, and drill
holes. (see letter, below, fr
Austin re. options for place
drainage holes.) When it w
we added the water throug
- testing how long it took to
the drainage hole, and mea
water level in the pvc pipe,
know in future, by looking i
pipe, when the water is low
Step 8.
Next, after a couple of days break, (to
heal our sore bodies and attend to work
in the studio) we built the second
(terraced) bed on top of the old garden
bed soil, (no more digging for us! :), using
the remaining screening rocks to make a
gravel pathway between. We waited until
the waxing moon to plant above ground
winter veggies, using a combination of
seedlings started in our glass house,
below, and seedlings from the local
nursery.

5. We still use grow vegetables in the in-ground beds on the western side of the garden, next to the (8
Glasshouse (which we saved from demolition by my mother's new neighbour last May, and reassem
We saved a third of the internal space for sitting. This is a fantastic place to escape to with a nice c
middle of a sunny winter day - freezing outside and so warm inside! Ben and I often go out there to
and finish off a nice bottle of red, after dinner.
In this patch, we currently have winter root veggies slowly coming up, – garlic, radishes, beetroot, c
next to spring onions (planted earlier), with various lettuces, spinach, bok choy, and herbs out of vie
Email message from Colin Austin, the inventer of Wicking Beds, June 2009 (I've
highlighted the essential information in red.)
Hi Maireid,
Well we have great debates here on this issue of the best depth for the water and
soil. Peter (of easygrowvegetables.com) and my neighbour and I spend many hours
over a bottle of red wine aurguing this point. If you do not like my answer write to
Peter (pva36152@bigpond.net.au) and you will get a different view.
What we do agree on is that water will only wick up some 300 mm. In my early
experiments I had my holes much higher than Peter but I watered until it reaches the
holes then I don't water again until all the water has gone. This means that the roots
are only in saturated water for a short time. This seems to work fine if the beds are
not regularly flooded by rain. We may get a couple of weeks when it rains every day
and submersing the roots for that length of time is definitely not good.
Peter had his holes much lower to avoid getting the roots saturated.

6. Now we are making our beds deeper with about 300mm of soil above the high water
line. Using the shade cloth this avoids any problem with water logging.
What we are debating now is how deep we can make the water reservoir. Out last lot
of beds were 500mm overall giving 200mm for the water resrvoir and 300mm for the
soil bed. This is working fine.
I think that we could make the water reservoir a little deeper still. This cuts down the
time between watering. On the latest bed I tried 300m and 300mm. Before, when we
had to dig the trench, making it deeper was hard work. Now that we're using raised
beds digging is not so much of a problem. Because I am old the last bed I made I
dug out all the top soil (about 300mm) then made the raised bed a further 300mm
which was quite quick to make.
I have only just put the seeds in so do not know how it will work but I am optimistic.
You can see picture on my other web site www.wickingbed.com
I will let you know how it goes.
Sorry there is not a simple answer. It also depends on what you are growing. I guess
if you are after a rule of thumb make the soil layer equal to the natural root depth of
the plant (for veggies about 300mm) and then decide the depth of the reservoir on
how long you want between irrigations, but you will be lucky to get any benefit above
300mm.
Colin