What Is a Wicking Bed — and How to Build Your Own

Every gardener eventually hits that point where they think, “There must be an easier way to keep everything watered!”
For me, that moment came one scorching Cape Town summer when I’d water the garden in the morning, and by lunchtime, it looked like I hadn’t touched it. That’s when we discovered the magic of wicking beds — and honestly, they changed everything.

A wicking bed is one of those clever systems that does the hard work for you, saving both time and water (especially in our climate where droughts and water restrictions are common).

So, What Exactly Is a Wicking Bed?

Think of a wicking bed as a giant self-watering sponge for your plants.
Instead of watering from the top, the water is stored in a reservoir at the bottom of the bed. The soil then “wicks” moisture upwards — just like a paper towel drawing up water — keeping the roots consistently moist without drowning them.

It’s like giving your plants their own little underground dam.

This system mimics how plants grow naturally near riverbanks or wetlands — roots reach down for moisture, while the topsoil stays light and aerated. It’s ideal for hot, dry areas like the Western Cape, Karoo, or Free State, but just as handy in humid regions like KZN, where overwatering can easily happen.

How a Wicking Bed Works (Layer by Layer)

Let’s break it down — it’s all about layers. Each layer plays a role in water management and root health.

1. Base (Reservoir Layer):
   This is the water storage zone. Usually about 15–20 cm deep, filled with gravel, river stones, or coarse sand. The water sits here, waiting to be drawn upward.
2. Separation Layer:
   On top of the gravel, add a layer of geotextile fabric, shade cloth, or thick weed barrier. This keeps the soil out of the water zone while still allowing moisture to travel upward.
3. Soil Layer:
   The top 25–35 cm is your growing medium — rich, well-draining compost mix. I use a blend of topsoil, compost, coco peat, and perlite for perfect aeration.
4. Wicking Column (Optional but Smart):
   You can add vertical pipes filled with soil or sand that connect the reservoir to the topsoil — this speeds up the wicking process, especially in bigger beds.
5. Water Inlet Pipe:
   A simple PVC pipe (about 50 mm wide) runs from above the soil down into the gravel. This is how you fill your reservoir. You’ll see water bubbling up once it’s full — that’s your sign to stop!
6. Overflow Pipe:
   Crucial! This outlet (drilled just above the gravel layer) allows excess water to drain out so your plants don’t drown after heavy rain or enthusiastic watering.

DIY: Build Your Own Wicking Bed

You don’t need fancy equipment — just a few simple materials.

You’ll need:

• A raised bed or large container (old bath, plastic tub, or wooden bed lined with plastic works great)

• Heavy-duty plastic liner (damp-proof course or pond liner)

• Gravel or stones for the reservoir layer

• Shade cloth or geotextile fabric

• PVC pipe (50 mm) for watering

• Smaller pipe or fitting for overflow

• Rich soil mix and compost

How to build it:

1. Line your container or raised bed with plastic so it’s watertight.
2. Add your gravel or stone layer (15–20 cm deep).
3. Insert your PVC pipe down into one corner so it reaches the bottom — this will be your filling pipe.
4. Drill a hole on the side just above your gravel level and fit your overflow pipe.
5. Lay your shade cloth or geotextile fabric over the gravel.
6. Fill the rest with your compost-rich soil mix.
7. Plant your veggies, mulch heavily, and water from the top just for the first week to get everything settled.

After that, you’ll only fill the reservoir every few days — or even once a week depending on your weather.

In the middle of summer, this setup has saved us hours of watering and hundreds of litres of water.

Why We Love Wicking Beds at VanZylStead

• They save up to 50–70% water — perfect for Cape Town’s Level 3–5 restrictions or dry inland summers.

• Plants stay consistently hydrated, reducing stress and increasing yields.

• They help prevent fungal diseases and mildew since the topsoil stays dry.

• You can even grow in containers or paving areas — great for small spaces, renters, or courtyard gardens.

• They’re low-maintenance — once set up, they practically run themselves!

We now use them for our tomatoes, peppers, herbs, and leafy greens, especially in our courtyard and container garden areas where heat bounces off the paving.

 A Few Pro Tips

• Mulch thickly: This slows down evaporation from the surface and keeps your soil temperature steady.

• Check the overflow: Make sure it’s not blocked — a flooded bed can suffocate roots.

• Feed through the topsoil: Add compost or liquid feeds like worm tea rather than into the water reservoir.

• Cover the inlet pipe: It stops mosquitoes from laying eggs in the water below.

From my growing garden to yours,

Tash & Family

Want to learn more about setting up raised beds, wicking systems, and smart watering for South African gardens?

You can grab one of our VanZylStead eBooks or become a member on our website for step-by-step guides, seasonal tips, and DIY tutorials — all designed for South African gardeners, by South African gardeners.

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