I’ve made lots of wicking beds in my garden; they are the ultimate time-saver! All kinds of containers can become wicking beds, as you’re only limited by your imagination. Here’s how to make a portable raised wicking bed from a common plastic planter.

What is a Wicking Bed?

A wicking bed is a type of self-watering raised garden bed that is both water-saving and time-efficient. It has a water reservoir at the bottom and growing medium (soil) on the top, which are separated by a layer of fabric. This allows the plant roots to ‘wick’ water up as they require it, so you don’t have to water often. They are great if you have limited water supply, have a busy lifestyle, or have health issues that make hand-watering difficult.

Wicking beds are the most water-efficient garden beds of all. Because the water is stored under the soil, it goes directly and only to the plant roots, eliminating the runoff and evaporation that occurs in standard veggie beds. This means you’ll only need to water every 10-20 days, depending on your climate and the season. Beds are easily refilled with water via a hose or pipe in one corner.

Essentially, wicking beds work by allowing plants ready access to a store of water held underneath the soil. An airtight, light-proof reservoir of water is held underneath the soil, which the plants draw from as they need it. This is what is called ‘wicking’. A pipe in one corner is used for refilling the reservoir with water as required. The bed is prevented from flooding by the addition of an overflow pipe, which is placed level with the top of the water reservoir. Sound complicated? It really isn’t!

While IBCs make wonderful wicking beds, they’re not the only type of container you can use. Many shapes, sizes and styles of pots and garden beds can be adapted for use as wicking beds.

As wicking beds need to contain a water reservoir in the base, containers without drainage holes are best. You can, of course, plug & waterproof all sorts of containers, but those with minimal or no holes will be easiest.

These plastic raised planters are readily available in Australia, and make ideal wicking beds, as the only drainage holes are at the bottom of the legs. They particularly suit renters and small gardens as they are small and portable.

I’ve turned mine into a bed for chilli plants. While chillies grow beautifully in pots and can withstand full sun all day throughout summer here in seQLD, they dry out quickly, so they’re the perfect candidate for a small wicking bed or pot.

How To Do It

Start by plugging up the holes in the bottom of the legs. I glued on these flat round stoppers which will help give a little extra stability as well.

As with any other wicking bed, a variety of media will work as a wicking agent. Here I’m using sand, but remember there is no one correct answer; use what is easy to source in your area & gets the job done. The second step is to fill the base and legs with sand, then smooth it out. Leave around 30cm space on top for the soil. 30cm is ideal soil depth for a wicking bed, as it has been proven to work best.

Next, create your overflow point. This is where excess water will drain out, once the reservoir is saturated. Drill a large hole and fit a small piece of pipe through it. Seal with silicone if necessary. Cover one end of the drainage pipe with shadecloth or geotextile fabric and secure it in place. This prevents insects entering and nesting. Here I’ve done this on the exterior, but it would have been neater on the inside! Ideally you will add a vertical inlet pipe at this stage as well. I didn’t include one on this bed, as it’s so small that I’m happy to top-water with the hose as usual.

Cut a layer of geotextile fabric to size and put it in place. Start filling the bed with growing medium. I started with some aged horse manure, then a layer of bagged compost.

Again, there is no correct thing to use here- many growing mediums will work, and I have used what I had available. As long as the soil is very rich & contains a high level of organic matter, you can use a variety of ingredients.

Next came the scrapings out of my house guttering, some garden soil, worm castings, a light layer of blood and bone, then more bagged compost.

Once I had enough growing medium in the planter, I watered it. I prefer to water new soil a little before planting out mature plants (as well as after transplanting), as it helps them stay in place as well as reducing transplant shock.

I planted my chilli plants out, mulched well, then watered until water overflowed from the outlet pipe. I like that this style of raised bed allows me to catch and re-use the nutrient-rich excess water; bonus!!

14 weeks later, shown below, my chilli plants are thriving during our very hot & humid subtropical summer. As you can see, I have more fruit than I can use, so I’m leaving the spent chillies on top of the soil to self-seed. This ultimately means I’ll never have to put another chilli plant into this bed, saving me lots of time in the long run.