How I built my wicking beds...

24 April, 2015

This is how I built my wicking beds:

1. Design the height of your bed, and where the water overflow will be and how much wicking space above.

My beds are built from my previous raised beds, and are a 20cm high timber frame propped on bricks.


The ground under the beds has been dug out around 5cms, so there is around 10cms of water reservoir under the level of the water outlet, which sits directly under the timber frame. This gives just over 20cms of growing space above the reservoir. While this is on the short side, I was essentially to lazy to do much about it. It seems to be working ok so far on my two first completed beds.

The space between bricks will be cemented in to match the gravel paths, when the beds settle a bit.

2. Line your wicking bed.


Under the pond liner is a layer of sand to protect the bottom layer of the pond liner. I used a standard 0.5mm PVC pond liner bought from my local rubber specialist. This was placed in the beds and when partially filled, attached to the timber frame level with the top edge with metal shadecloth fixers.


The excess pond liner was then trimmed to the top edge of the timber.

I then used copper tape to cover the edge of the beds and bridge the gap between timber and pond liner. It may help prevent slug and snail invasion. Mostly I think it just looks nicer. It should also prevent stuff getting stuck between the timber and pond liner.


3. Fill your wicking bed.

I used a base of a mix of sand (closest to the pond liner) and gravel which I had plenty of from the graveled area which I had converted to paving.

4. Divide your water wicking and soil.

Put down a layer of horticultural fleece over the water reservoir layer.


This is mainly to reduce the soil/sand layers from mixing, from what I have read. I'm not sure how essential that is, given I have heard plenty of success from wicking beds which are only filled with soil/compost, with no separate base.

With this in mind I have experimented, and have put down the separating layer in two of the six wicking beds. The others have no separation between soil and sand/gravel layer. We shall see if there is any difference between growing or how the soil/sand mixes over the years of growing I hope to get out of these.

5. Make your water outlet.

I cut a hole in the pond liner just below the level of the timber. A re-purposed piece of plastic piping was wedged in and sealed.

6. Fill the remainder of your beds with soil.

Simple enough. Just takes a lot of muscles.

7. Add a few worms to help aerate the soil.

8. Plant!

Yay. The fun part. Finally.

Notes on differences with other methods.

Many wicking beds have a pipe to water straight down to the water reservoir. I didn't do this as with my first two beds I found top watering until the water started trickling out of the outlet was good enough to know when I had watered enough. I figure I can always dig out a corner and put in a pipe if I think it will be useful.

Total cost per 2.4x1.2m bed:
Pond liner                $102             
Sand (approx)             10
Attachers (approx)        2
Copper tape                  7

Total $121 per bed.
If you had to buy timber its around $12 per 2400 sleeper, so add $36.

In hindsight that seems really quite cheap. I'm well pleased with that. Especially given how my I save on buying my fruit and veg, let alone the water savings I should get.

6 comments:

  1. That's SO much cheaper than the ones I bought (that I still had to do all the grunt work to get assembled.)
    Nice work.

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    1. Cheers! I'm happy that I'm re-purposing a lot of stuff, so timber, bricks, soil, gravel etc was mostly free (in that I had already paid for it, of course). Hopefully the results will justify the effort.

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  2. Excellent guide covering all the detail, thanks.
    I have wondered about variations I had previously read, like separation between base layer and soil,
    you explained these all so well.

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    Replies
    1. My pleasure. I will be sure to report back on whether there are any practical differences between separation or no separation beds.

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  3. I would have so much trouble with that. I'd probably put holes in the liner instantly. I'm guessing you are very careful with the trowels around it.

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    Replies
    1. Yes, a lot of care will need to be taken. I'm currently working out my external bed staking method, and will be careful with any required digging. But I shouldn't need to dig much, given the soil will not be stepped on or compacted in any way, and the worms should airate the soil for me. Any planting will be shallow enough (seeds or small seedlings) to not require any dangerous activity, I hope.

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