Simple self watering or wicking bed made from a plastic barrel.

In our latest attempts at growing more than just a few herbs we decided to build a wicking bed. We had been looking at a few videos on You-tube like this one and this one on Rob Bobs channel and thought that even if we weren't prepared to experiment on that scale right now, we did however have a blue plastic barrel hanging around that we thought might do the trick, albeit on a smaller scale.

The idea of a wicking bed is that it has a storage area or reservoir of water at the bottom of the bed and the roots and soil "wick" the water up to the roots. Sort of in the way that, even though only a corner of the towel is hanging in the pool, the water climbs up the towel making half the towel damp, not just the corner that landed in the pool.

So one afternoon we gathered together the bits we thought we would need, and here's what we did...

First of all we cut our barrel in half and added some handles so that we can move them if we have to when they are filled with dirt and water.

Its a very basic rope handle with knots on the inside and a piece of pipe to help protect your hands on the outside. It made all the difference when we went to move it to the place we wanted it - which was not where we built it! If you aren't putting handles on your barrel - pop it into place before you start filling it. They get heavy quick and have nothing to grip onto move them!

The next step involved rolling a piece of ag pipe (pipe with lots of holes in it. Usually used to help water drain away) around in a spiral in the bottom of the barrel. One end starts in the centre of the base and coils up until the edge of the barrel is reached. Then the pipe comes up the side and becomes you watering inlet. (Sorry no pictures of this bit. The Husband had got to this point while I was getting the sand and wasn't pulling it all apart for me to photograph!)

We found it really hard to keep the coil in the bottom of the barrel and ended up using bricks to hold the coils down. Once you have your coiled ag pip in the bottom of the barrel lift up the bricks one at a time and put a piece of weed mat over the top and put the brick back down (or the pipe will spring out and wrap itself in the weed mat.) Tuck your weed mat around the ag pipe. The idea is that you are trying to stop as much sand as possible from entering the pipe. The water can travel through the weed mat but the sand/dirt cant.

Put your sand in the bottom of the barrel on top of the weed mat and take your bricks out as the sand gets heavy enough to weigh it all down and keep it in place. Just cover the weed mat at this point; Ultimately you will be filling the barrel with a quarter sand and the rest dirt and plants. Once you have the pipe in place - cut it to the height of the barrel or just and inch or two higher.Once you have the pipe in place - cut it to the height of the barrel or just an inch or two higher.

Once you get to this stage, cable tie the water inlet pipe to the side of the barrel to stop it from falling over. Then drill a hole to put a grommet in to make an overflow pipe.

If you don't put in an overflow pipe your wicking bed will turn into a pond when it rains heavily and will kill the plants and be hard to empty.

 

 Once you have the grommet in, push a short length of pipe into the grommet. You want it to extend a few inches into the sand eventually. The next step is to put a piece of weed mat over the end of the pipe and secure it with a  cable tie. Internet research showed that a plain hole simply blocked up with sand after a bit of time and turned the barrel into a pond. If you put the weed mat over the hole on the outside or have the pipe sticking out of the barrel (not on the inside like we have done) and put weed mat over it - it grows algae, and again, blocks up.

 

 

Once you have your overflow pipe sorted, fill the barrel a quarter full with sand covering the outlet pipe. Did you notice we have moved the barrel to its permanent place before we started to fill it!?

Before we went any further, we cut the top off a water bottle and slid it over the top of the inlet pipe so that we didn't spill any dirt in it and fill up our reservoir with dirt.

Then a layer of cane mulch went in. Our cane mulch is about 3 inches deep. The idea here is that if you are digging around in here you will find the mulch layer (if you go deep enough) and will know that you are really close to your reservoir. It also keeps the dirt and sand separate if you need to empty it at any point.

Then fill your barrel to the top with your dirt/compost/growing medium. See how that bottle is protecting the inlet pipe from filling up with dirt?

Now fill your reservoir with water.

You'll know when its full when your overflow pipe overflows!

It runs clear after a few days.

 

 While you are waiting for your reservoir to fill, pop some mulch on the top to protect the soil and seedlings from the hot sun.



Once the reservoir was full, I watered it from the top as well just to make sure that all the dirt was damp before I put in my seedlings. We put our mesh cages over everything to keep out the chooks. (Between the possums, sun and chooks - you wonder why you bother some days...)
 

This barrel has some rocket seedlings in it and so far so good. The seedlings seem to be able to survive a day in the sun although this spot doesn't get the late afternoon sun which will help while they are little but not be so good once they are established. I have trouble with the harsh summer sun decimating seedlings before they can get established. Even though I water my plants morning and night, when I'm at work all day the sun wins and after a couple of days the seedlings give in and die.

So far with this system, the seedlings are still being watered (with a watering can and through the inlet pipe) once a day and have survived about 10 days so far - so I'm hoping for some salad contributions from this barrel down the track!

We want to try this on a bigger scale and have been scouring the world for a free food grade IBC cube tank to cut in half and do this with. Both of the video links are to IBC wicking beds - but we thought we would trial the technique with what we had lying around the yard.

I put these barrels in a place that doesn't get direct sun all day due to the trees. I think in summer this would work well but I can see that in winter I may be able to grow things in full sun with a wicking bed. I can usually grow a small amount of tough veges in winter but nothing in summer here in Brisbane... I either have full sun or deep shade...

Have you tried wicking beds? What did you think? Any advice to add?

 

Score card:
Green-ness: 5/5 for repurposing things you already had. 
Frugal-ness: 5/5 for only having to buy sand.
Time cost: About an hour from go to whoa.
Skill level: Confidence with power tools...
Fun-ness: great fun to see your seedlings still alive each afternoon!!