Introduction: Corten Steel Wicking Beds

So what is a wicking bed ?

It's essentially a self watering garden system. You can see in the photo's its a fairly basic but highly effective system.

It's very water efficient and low maintenance with the added benefit of having your garden watered when you go away on holidays or as in my case when school holidays come around and the place is deserted for weeks.

I decided to re work a section of our garden that had very little soil depth and near zero drainage. During times of heavy rain the ground would flood and not much was really growing. With the wicking bed having an overflow port fitted even if there are heavy rains the excess water is drained away from the garden beds.


I had to create four garden beds and it was to suit a existing and specific space so the size dimensions and quantities will need to be adjusted to suit your own needs.

The list below is what I used to make one garden bed.

I sourced all my materials except the Corten steel from Bunnings.

1 x 2400mm x 1200mm sheet of 2mm Corten steel cut into 3 x 400mm x 2400mm strips.

1 x 6m length of 10mm straight reo bar.

1 x Galvanised metal flange nut with a 20mm internal thread.

1 x 20mm threaded plastic irrigation connector with a 15mm barb.

1 x 2m x 4m sheet of pond lining.

1 x 10m roll of geotextile.

1 x 400mm of 50mm pvc pipe.

1 x 50mm pvc elbow.

1 x 50mm pvc cap.

1 x Roll of packing tape.

1 x 7m length of 65mm split ag pipe.

3/4 m3 of 20mm drainage scoria.

1m3 or garden soil.

A few buckets of sand.

Pinchweld rubber (optional)

Step 1: Creating the Frame

I began by cutting the reo bar to suit the existing size and shape of the garden bed. I bent the reo bar to suit the rounded side of the bed and tacked the reo bar frame together. I then proceeded to cut the Corten steel strips to suit the reo frame. Because I was digging the garden beds out to depth of 100mm the width of my Corten steel was cut to 400mm to allow sufficient soil depth and to create a big enough water reservoir. I placed the reo bar at 100mm high from the bottom edge of the Corten steel. With the 100mm depth of the excavated depth of the garden bed added I had used the reo as a guide for my scoria depth later on. On one of the flat sides of the Corten steel just under the reo bar I drilled a 15mm hole and welded the 20mm threaded steel nut on the inside of the frame to use as my overflow hole.

Step 2: Excavation and Levelling

Next step was to excavate the existing garden bed to a depth of 100mm and remove any rocks or sharp objects. I also added a thin layer of sand to level the ground. This doesn't have to be perfect as the water reservoir is quite large. The key is to remove anything that might puncture the pond lining.

Step 3: Fitting the Pond Lining

I draped the pond liner into the garden bed and roughly taped it into place, making sure it is above the height of the reo bar by about 50mm everywhere. Don't stress to much as the tape will be removed later on.You should now add some water to assist the pond lining into finding it's on place and to level itself out. Just enough to cover the bottom and around all edges. As the water is filling up gently remove the tape as the lining starts to tighten and find its own place. Once it has you can put a small hole in the pond lining inline with the welded in place steel nut and attach the barbed fitting to act as an overflow. Have the barb facing into the garden bed so it isn't knocked off from people walking past.

Step 4: Fitting AG and PVC Pipe.

The next step is to connect the pvc pipe together and place the 90 degree elbow into the slotted AG pipe.Take the straight section and add the elbow to one end. Tape this end into the AG pipe and create a roll of Ag pipe in the bottom of the garden bed. Add some scoria to keep it in place and have the pvc pipe rest against the corner. Place the cap on top to stop any foreign materials being placed in and to stop mosquitoes breeding in the water. The AG pipe is important as it create's an extra water reservoir as the scoria cannot displace the water.

Step 5: Scoria, Geotextile and Soil

Add the scoria to the level of the drainage barb being careful to to break it.

Add two layers of Geotextile fabric over the top of the scoria making sure it reaches all the edges. This stage is important as the fabric stops the soil from mixing with the scoria and also creates the wicking effect.

Now add a good quality soil/compost mix until its just below the top height. Allowing some space for mulch to be added later.

Also fill the reservoir up via the pvc pipe til it runs out the overflow pipe to make sure its working correctly.

Step 6: Finishing Off

Now you can plant your plants!

We chose to create a bush tucker garden so we planted all indigenous plant from our local area and a few from other areas to see how they would go.

We also added pinch weld rubber to the top edge of the Corten steel to stop any little hands cutting themselves. It's reasonably expensive and wouldn't be need needed in the home environment.

Water the plants in from the top for the first few weeks so the roots can grow downward and allow the wicking process to begin. Then you can add mulch to stop the surface from drying out.

The wicking bed style of garden bed can be styled to suit any size or shape its just up to your imagination ! It doesn't have to be as large of complex as ours are, they can be made from old plastic tubs or any material that will hold water.

Have a go and see what you can create !!

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