How to make a wicking bed: a veggie patch watering solution for hot Australian summers | Australian lifestyle

Hotter summers make soil conditions tougher, and the poor vegetable garden beds suffer the most. One way to get around this is to come up with wick beds.

The basic theory behind wick beds is that the water is stored in an airtight reservoir underground and “soaks” it up through the soil to the roots above as the plants evaporate moisture through their leaves.

Depending on the size, the reservoir can keep the soil moist for up to 10 days. It practically prevents evaporation from the soil and eliminates the risk of leaf scalding that can occur if you water your plants from above.

You can pick up everything you need at the hardware store.

How to make a moisture wicking bed

Equipment you need
(the lengths depend on the size of your garden bed):

  • A raised bed with a fixed frame

  • Brick sand (very fine sand), enough to cover the bottom of your garden bed to a depth of 50 mm

  • Food grade plastic film, enough to line the entire garden bed all the way to the top

  • Two lengths of 50 mm slotted agricultural pipe, one long enough to be one-third the length of your garden bed; the other long enough to reach the full length of the bed

  • 50mm poly tube, enough to reach your garden bed from top to bottom

  • 25mm poly tube, enough to be halfway up your garden bed

  • A poly elbowto connect the shorter piece of the 50mm slotted agricultural pipe to the 25mm poly pipe

  • sealantto seal the agricultural pipe

  • 14mm building aggregate (blue metal gravel) enough to fill the bottom half of your garden bed

  • Geotextile fabric, enough to cover the entire base of the garden bed

  • High quality topsoil, enough to fill the top half of your garden bed

  • Mulch (pea straw or lucerne straw), enough to cover the top of your garden bed to a depth of 50mm

A diagram of a self-transporting garden bed
A diagram of a self-transporting garden bed Photo: Australian Institute of Botanical Science

Step 1: set up your raised bed

A raised bed can be formed from old corrugated iron.
Old corrugated iron can be formed into a raised bed. Photo: Mark Kolbe / Getty Images

Your raised bed can be made from anything; ideally, however, it must be at least 50 cm high, with a solid frame and base (like a corrugated iron container, wooden box or old bathtub). Make sure it’s on a flat and stable, level surface – it’s best to lay a bed of sand first.

Step 2: add the liner

Make sure that the bottom of the garden bed is free of sharp objects. Consider covering the substrate with a layer of brick sand, just in case. You can also use an old rug.

Then spread the food-safe plastic evenly over the bottom and sides so that it almost reaches the top of the garden bed. If your plastic is thin, you can double it up before using it.

Polypipe can be used to indicate when you have enough water in the garden bed.
Polypipe can be used to indicate when you have enough water in the garden bed. Photo: Miguel Gutierrez Jr./The Guardian

Step 3: insert the overflow pipe

Cut a hole on one of the short sides of the garden bed that is slightly larger than the agricultural pipe you will be using. Also cut through the liner. Install the shorter piece of agricultural pipe so it protrudes from the hole, then seal it on both sides to ensure watertightness.

Attach the poly elbow and 25mm poly pipe so that the top of the pipe sits at the same level as the top of the stones in your bed. This poly tube allows you to indicate when you have enough water in the garden bed and it can be swiveled to drain the water from time to time to avoid stagnation.

Step 4: shape the water reservoir

Add gravel. Lay the longer piece of agricultural pipe across the center of the gravel from one side of the garden bed to the other. At the end of this farm pipe that is closest to the overflow pipe, place the 50mm poly pipe so the top of the pipe is higher than the top of the garden bed (you’ll need something to hold it in place until the soil is added). This is the inlet pipe that you use to fill the garden bed with water (using a hose or a watering can with a narrow spout).

The gravel between the farm inlet and overflow pipes prevents water from flowing through and out of the garden bed before the container is filled and allows you to fill the container quickly without flooding the garden bed back, which is really important.

It's important to keep the soil healthy by adding fresh compost to the garden bed before planting.
It’s important to keep the soil healthy by adding fresh compost to the garden bed before planting it. Photo: Pakula Piotr / Alamy

Step 5: check for leaks

Add water to the garden bed through the inlet pipe and let sit overnight to see if there are any leaks.

Step 6: insert geotextile fabric

Place the fabric on the reservoir. If you don’t have access to geotextiles, you can use a folded piece of shade cloth. Whatever you use, make sure the material moves water up but prevents the earth from sinking down.

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Step 7: add soil

Pour in the mother earth. To keep your soil rich and healthy, make sure you add about 4 inches of fresh compost to the garden bed each year before planting.

Step 8: start planting

Treat this like a normal raised bed with the tallest vegetables in the center and the shortest or creeping species around the edges.

Note that the driest soil is on the surface, which will help prevent weed growth. You need to hand water the seedlings from above for a few weeks until their roots get going. When you’re done planting, add a layer of mulch.

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