Not long after moving to our new farm, we wanted to move towards a more sustainable way of living. L is a avid researcher, and of course has spent many hours researching different ways that we can achieve this and be more sustainable, and at the same time reduce our living expenses.
One of our first projects is to construct a garden bed so that we can grow our own vegetables. So much of the fruit and vegetables that we buy from our supermarkets is either imported from other countries or been in storage for months prior and been injected with chemicals prior to being cut up for our dinners. It’s nice to have the option of going out to a garden, and having in season fruit and vegetables that you can pick straight from the garden or tree and eat, that night for dinner.
We looked into different types of garden beds that would suit our area and be easy to maintain. We came across a garden bed called a wicking bed.
A wicking bed – which can also be called a self watering garden bed is constructed a little different to an ordinary garden bed in that it uses its own reservoir to water the garden from underneath the soil rather than watering from the top. It’s particularly great for spring and summer vegetables as often it is hard to water the plants enough, dependant upon how much each plant needs and when we remember to water. Whereas the wicking bed allows the plants to get as much water as they need, and all you need to do is fill the reservoir – say, once a week or so.
I have just completed our second wicking bed and thought to share how I did it, so that you can see how easy it is. You will note from my earlier posts, Im not a tradesman and so anyone can really do this. You can build these as large or a small as you like depending upon the space you have. You can also do them in the ground, but for our beds we have built them above the ground, for ease of access and maintenance.
Materials I used:
- 6 x 3m lengths of 200mm x 50mm treated pine boards – eco board – or one without arsenic
- 6 x 1.5m lengths of 200mm x 50mm
- 4 x 800mm lengths of 100 x 100mm cedar posts
- Approx 50 No. x 100mm galvanised screws
- 4m x 2m of thick black plastic – or pond liner
- 1 x 600mm length of 50mm pvc
- 1 x pvc T piece
- 6m of 65mm slotted pipe
- Duct tape
- 1 x 50mm bracket for holding the 50mm pvc
- Approximately 1 cubic metre or between 1.7 & 2.2 ton of 14mm crushed rock
- Approximately 2 cubic metres of topsoil – which can include some of your own compost and other ingredients
Step 1 – Set out – prepare the area that you want the garden bed. I had already constructed one (as you can see in the background) and so it made it a bit easier this time to start the setout. I simply measured 1 metre off the existing bed but also ran string lines out to dig the stump holes. You also need to work out what size you want your garden bed. Our beds are 1.5m x 3.0m long.
Step 1: Set out
Step 2 – Holes for posts – Measure the distance between the posts and dig the holes. The materials I have used are treated pine (eco – treated) 200mmx 50mm for the boards and 100mm x 100mm cedar posts. I wanted the beds to be 600mm off the ground and so have the made the posts 600mm out of the ground and about 200mm in ground. Its not 100% essential you have big footings for the posts, so its your choice if you want to use concrete or not or just backfill with soil. As you can see I have dug 2 of the holes, but I wont bore you with the rest… This requires a crow bar (in our case) and a shovel, and a beer waiting for you at the end…
Step 2 – Holes for the posts
Step 3 – Installing the posts – As per step 2, I have used 100mm x 100mm cedar posts and now set them out so they are at right angles to each other – you can do this by using the 3,4,5 triangle rule (thanks Mr Pythagoras) to ensure you have the posts at 90 degrees and parallel. As you can see I have used the other garden bed to prop one of the posts, as I was doing this by myself and needed some other way to prop the post and make sure it stayed straight and let the rapid set concrete do its work.
Step 3 – Installing the posts
Step 4 – Attaching the boards – once the posts are set. Cut your boards to suit – remember measure twice cut once… Due to the size our our beds we were limited by the 3m boards and so to get the largest bed I could we made them with butt joints along the lengths and concealed the edge of the boards with the width boards of 1.5m, therefore I had to set my posts 50mm in from outside so that the length boards would butt into the end boards. Im a bit of a perfectionist and so I made sure each board was level and used packers or little rocks or pieces of timber offcuts, where the treated pine was bowed or twisted and could not give me the perfect level. For the fixings, I used 100mm galvanised screws.
Step 4 – attaching the boards
Step 5 – Level the inside of the bed. Once you’ve completed the boards (below) you need to level the base of the ground inside the bed. As you can see in the photo above the ground is not level – the sun is shining through the bottom of the board. So I just shovelled some dirt back inside the bed and levelled it off. Its important to have a level base as you want the water not pond up one end of the bed as it will affect the wicking (transfer of the water) up to the plants. Make sure you also remove any rocks that may stick through your plastic as you’ll see in step 6. I did also use a small piece of timber in the middle as my boards were a bit twisted and needed a support mid span.
Step 5 – Level the inside of the bed
Step 6 – Insert plastic – tanking – As you can see in the photo below, we then line the inside of the bed with plastic. This is not just your usual plastic it is quite thick and is often called pond liner. Go to your hardware store or Home Depot and ask them. It needs to be able to hold water. You place the plastic in and staple it to the top board, try and make it as even around the outside as possible. Due to the bed being rectangle it is difficult to get the corners right so just bunch the plastic up in the corner and staple as best you can.
Step 6 – Insert plastic – tanking
Step 7 – Watering point – now I must apologise as I didnt take a photo of the installation of the installation of the slotted pipe (ag drain), so I will do my best to explain… I used 65mm slotted pipe and a piece of 50mm PVC. I fixed the PVC to one end of the garden bed. At the base of the PVC pipe I used a PVC ‘T’ piece (50mm) connecting the slotted pipe to both sides of the ‘T’, I used duct tape to connect the slotted pipe to the T piece. I used about 6m of slotted pipe and made an ‘S’ shape in the bottle of the bed. When you add water to the bed via the 50mm PVC pipe (at the end) it doesn’t really matter how the slotted pipe is laid as you will see later.
Step 8 – Add crushed rock – Our bed is 600mm deep and you want around 400mm of topsoil to grow your vegetables or plants. On top of the slotted pipe you add approximately 200mm of crushed rock, some people call it scoria or gravel. The main thing is to get a product that has minimal amount of fines in it. I used a 14mm aggregate (blue stone), which has a smallest stone of around 7mm. In the photo below you can see the piece of the 50mm PVC pipe at the end. Make sure you make the crushed rock level too.
Step 8 – Add crushed rock
Step 9 – Install an outfall spout – at the top of the crushed rock cut a hole into one end of the bed. This hole is used to allow water to drain from the bed when you are filling the spout. When adding the water, keep filling until it comes out the spout.
Step 9 – Install an outfall spout (1)
Step 9 – Install an outfall spout (2)
Step 10 – Install geofabric – The next step is to install a membrane between the crushed rock and the topsoil (where you grow your plants) the material needs to allow water to transfer through. Again your hardware store will be able to help. The material as you can see I used is like a fleece. This stops the fines of the topsoil filtering down into the crushed rock. I bring the geofabric up the sides about 150-200mm and use staples to fix it to the wall of the beds. Cover the drain pipe with the geofabric too.
Step 10 – Install geofabric
Step 11 – Install topsoil – The final step (woo hoo). Go to a good nursery or garden supply place and get some topsoil. You can get some good blends made up for you. If you tell the salesperson what you’re doing (making a vegetable garden), they’ll be able to help you. We have a number of compost bins at our place and so we used some topsoil and compost to aide the development of the plants. For a really successful bed you should also add some blood and bone too. Finally add some straw to reduce the evaporation of water from the top part of the soil and you’re done!
Step 11 – Install topsoil
In the above photo I havent yet gone around and neatened up the plastic but will do that tomorrow. I will also set about painting the ends of the timber too to ensure a longer life for the timber.
Hey I hope that was pretty straight forward and gives you an idea of how to make a wicking bed. If you need any further help, drop me a comment and I’ll see what I can do.
You’ll be amazed at the produce you get from this form of garden bed!