Under the Choko Tree By Nevin Sweeney

In-Ground Wicking Vegetable Bed

The wicking beds that I have constructed so far were above ground, which made them comparatively easy to construct. I just used treated pine veggie beds, lined them with the plastic sheet, put in the filler tube, wood chips and growing medium and whammo! Instant wicking bed!

While this is a good thing to do and is covered in some detail elsewhere on the site, I wanted to see if the current bed system, where I grow most of my vegetables in the back yard, could be converted across to a wicking bed style of thing. That way I would have my main vegetable culture area converted to the water efficient wicking bed system. I have 13 beds each one being about 1 metre x 2 metres – the size of my chook tractor – that I use for my main area of vegetable production. The above ground wicking beds are used for perennials like asparagus and rhubarb as well as some special stuff like cotton and sunflowers, but my main production area remained a conventional type.

The chook tractor spends two weeks on each bed twice as year and this idea hit me at about the same time that the chooks were moving to a new bed, so what better time to start than now? The first and most back breaking job was to dig out all of the soil from the experimental bed down to about 500mm. So that I didn’t give the lawn too much of a hard time (I know, I know!) I put down a tarpaulin of about 4 metres squared to shovel the dirt onto. This done I could start.

Part way through digging out the bed

I dug down on the first attempt to the depth of a spade spit (1 spit = the length of the spade blade = 290mm). While I don’t dig the veggie beds any more, I let the chooks and the worms do it so the soil was reasonably friable and “easy” to dig ie it only half killed me rather than going for the whole 100%. On a number of occasions through the digging exercise I had cause to ruminate on Dr Phil’s immortal words “What........were you thinkin’?”. Part way through while digging against the western edge of the bed I found archaeological evidence of a previous veggie patch, the remains of a wooden sleeper I had previously used as an edging for the patch before the bed system. Fortunately it was fairly rotten and some gentle persuasion with an axe talked it into moving with comparative ease.

The digging completed

Once down to the one spit level and having shifted a remarkable amount of good, fertile soil, it was then just a case of digging down a further 200mm. Although at this level the soil was somewhat more compact and resulted in additional entertainment for me, especially after moving all of the original dirt. Two aches for every muscle!

and this is the dirt that came out of it!

Once the hole was down far enough it was time to fit the plastic inside it up to about the 200mm above the bottom mark. You should always check that you have all the gear before you start one of these projects, but typically I forgot. Luck was with me however and I had just enough plastic sheeting left over from the previous two wicking beds to be able to line the pit. With the pit lined I fitted in the filler tubing of 50mm agricultural drainage pipe (there was plenty of that left) and filled the hole in to a depth of 200mm with the same type of wood chips that I used for the above ground beds.

The liner and filler tube in place


The wood chips in place

I then filled in the bed with the remaining soil to the top of the timber surround and even mounded it up a little. This still left a considerable amount of dirt left on the tarp, good soil that I didn’t want to waste. If you go down this route I suggest you work out where you are going to put the excess soil so it doesn’t get wasted before you start to dig! I was lucky, we were replanting some trees in the front yard and I was able to use the excess soil (a good 5 or so wheelbarrow loads of the stuff) to make up a bed to plant the fruit trees in.

The soil replaced to fill the bed

All I had to do then was mulch the bed in our normal way and plant out veggie seedlings and of course fill up the wicking bed reservoir. I filled the reservoir out of one of the rainwater tanks behind the garage just by gravity. It is now all complete and ready to go.

By nature I am fairly cautious and I will wait and see if there is any difference in the performance between the new wicking bed and the standard veggie beds. While there was not much cost involved in setting it up as a wicking bed, it was a crap load  of work for me so I would have to be thinking that it is worthwhile before I go and convert the rest of the 13 beds (OH, my aching back!) to wicking beds.

Watch this space!

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