How to Make a Wicking Bed (Step-by-Step)
OK, let’s dive into an overview of how we make our wicking beds with a few extra tips and tricks and tasty morsels of helpful gardening advice thrown in.
1 Choose and Position Your Bed
Where you place your wicking bed has a big impact on how well it performs — and how easy it is to use over time.
Here’s what to consider:
- Sunlight: Choose a spot that gets good sun for most of the day. More sun = better growth.
- Access: Make sure you can comfortably reach all areas of the bed — especially if you’re using wheelbarrows, prams, walking aids, or working in a tight space.
- Surface: Wicking beds can go on soil, gravel, concrete, or pavers — just make sure the surface is firm, level, and not sharp enough to damage the liner.
- Slope: If your ground is sloped, do your best to level the bed. A flat base ensures water spreads evenly through the reservoir and wicks properly.
🌱 Pro Tip: Align beds north–south for even sun exposure on both sides. For east–west beds, plant taller crops on the south side to avoid shading the rest (southern hemisphere logic!).
2 Build or Place the Container
Use a raised bed made from sustainably sourced timber, corrugated iron, or repurposed materials like IBCs. Timber is especially easy to work with. Here in Melbourne, Australia we love Monterey cypress for its durability, local and ethical sourcing and smell!
What size should your wicking bed be?
The ideal width of your bed depends a little on your arm length, and we recommend something in the range of:
- 60–90cm wide for single-sided access (against a wall or fence)
- 1.2–1.4m wide for double-sided access (free-standing)
Height matters too:
- 60cm tall is our sweet spot — it offers around 25cm of water reservoir and 35cm of soil depth, and is a great height for ergonomics.
- Shorter beds down to 40cm work, but will require more frequent watering.
- 80cm beds are great for accessibility, but don’t offer additional water or soil depth benefits.
.
Make sure it’s built strong — use proper corner posts and bracing, especially for timber beds, as a full wicking bed gets heavy fast.
How to Build a Timber Wicking Bed (DIY)
- Cut your timber to size: For a 60cm high bed made from 20cm high sleepers, you’ll need 6 long and 6 short lengths.
- Assemble your long sides: Screw three long boards together into sturdy corner posts for each end. Leave a space at the end of the panel to fit your short lengths.
- Stand up your long sides: Use long clamps to hold the short end boards in place at each end.
- Check it’s square and level!
- Screw in the end boards: Secure each short board into the corner posts — avoid screwing directly into end grain.
- Add internal bracing: For beds over 1.5-1.8m long, add at least one brace to stop bowing once filled.
- Stand back and admire your handiwork. Nice one!
If using IBCs, make sure they’re food-grade and haven’t previously stored chemicals. IBCs can also degrade in direct sunlight, so it’s important to paint or cover them to protect the plastic over time.
When choosing corrugated beds, opt for quality Australian-made options without horizontal bracing in the lower half — these braces often get in the way of liners and plumbing. Round corrugated beds are a great alternative: they’re naturally self-supporting and usually don’t require any internal bracing at all.
3 Install the Liner
Your liner is one of the most important parts of the entire wicking bed system — it’s what holds the water in. Choose a heavy-duty liner that’s UV-stable and certified safe for drinking water contact (often labelled as potable-grade or AS/NZS 4020 compliant in Australia).
Getting this right means protecting both your plants and your health — while also ensuring the longevity of your bed.
We bulk-buy the best liner we can find for our own installations and share it through our shop for DIYers who want to get it right the first time. Our liner is available custom-cut to your bed size as part of DIY Wicking Beds kits.
⚠️ A Word of Caution: Builders’ plastic is cheap and easy to find — but we don’t recommend it. It’s not rated safe for food or drinking water, not UV stable, and far more prone to tearing and leaking than proper liners.
How to Line a Wicking Bed (Like a Pro)
- Clear the bed of sharp objects — use offcuts of geofabric to comevr screw and rivits inside corrugated metal beds.
- Lay the liner out fully on a clean, flat surface,
- Measure your bed — you want the internal length, width, and height of your bed.
- Start by folding in the height on one edge, then measure across the internal width (at its narrowest) and fold the second side. Repeat this for the other dimension.
- This creates a rectangular or square shape — matching the internal footprint of your bed.
- Carefully lower the folded liner into the bed. Gently fold each side to line the walls and use clamps to hold it in place.
- Tuck the liner firmly into corners with a little excess — too much is better than not enough.
Think of it like folding an inside-out birthday present — you want it neat, tucked, and stress-free in all the corners.
And a leaking wicking bed? It’s frustrating to fix, usually messy, and often means starting over. Better to get it right from the beginning.
4 Set Up the Plumbing
The critical system that keeps your wicking bed running smoothly.
Proper plumbing is what transforms a raised bed into a true wicking bed — allowing you to control, fill, drain, and maintain your water reservoir with ease.
The Inlet (Filler Pipe)
The inlet is how you get water into the reservoir. It’s typically a vertical pipe that sits above the soil surface for easy access. In our setup, the inlet includes a hose tap connector and a short length of agi pipe to help distribute water quickly throughout the base of the bed — without flooding the soil or causing backflow.
How to install the inlet:
- Place your inlet pipe in a corner — ideally close to your tap and in a spot you naturally approach the bed from.
- Connect and lay the agi pipe flat along the base of the bed — this helps the water spread quickly and evenly during filling.
The Outlet (Overflow Pipe)
The outlet allows excess water to escape once the reservoir is full. This prevents over-saturation of the soil layer. Most DIY guides place the outlet partway up the side or at the top of the reservoir layer — but this limits your ability to drain the bed or check water levels.
The VEG 4-in-1 overflow system
This is our signature outlet installed at the base of the bed with a vertical riser. This gives you:
- Easily check the water level
- Handle overflow from rain or overfilling
- Fully drain the reservoir to flush out salts or contaminants
- Switch into ‘rainy season mode’ for optimal moisture control during wet weather
How to install the outlet (for timber or metal beds)
- Mark a point 5–6cm above the base of the bed.
- Drill a 35mm hole through the wall using a timber or metal hole saw (avoid touching the liner).
- Hold the liner against the hole and mark where to cut. Carefully cut a hole just big enough for the tank fitting.
- Insert the 25mm tank valve through the liner and bed wall (For corrugated beds, use adapters to create a snug fit).
- Apply plumbers’ silicone and fit the washers to ensure a watertight seal.
- Secure the tank fitting to the bed using the supplied screws.
- Attach the outlet elbow and riser using Teflon tape to complete the seal.
Want to make assembling your plumbing easy? Check out our VEG Plumbing-Only Kits. All kits include detailed written and video instructions for a stress-free install.
5 Add the Reservoir Layer
This is where the “wicking” actually happens. The reservoir layer sits at the bottom of the bed, storing water that your soil draws upward via capillary action.
How to Construct Your Reservoir
- Order your screenings or fill material based on internal bed volume. (We’ll send you our levels and volume calculator when you purchase a product.)
- Carefully fill the bed up to your reservoir height — usually 30–35cm from the top of the bed.
- Fill with water to the top of the screenings and use the water surface to level the aggregate.
- Cut your overflow pipe to match the exact height of your water level. This sets your reservoir depth.
We recommend 5–7mm bluestone screenings — also called quarter minus, blue metal, or stone screenings. This size strikes the right balance between:
- Water storage — no crates or pipes needed
- Upward wicking power — lots of surface contact
- Lateral movement — spreads water quickly and evenly across the bed
🚫 Why We Don’t Recommend Scoria
- Scoria is lightweight and porous, but in the common 10–20mm sizes, it performs poorly in wicking beds.
- Water tends to sit low in the bed rather than rising into the soil — and it often misleads users into thinking it’s working (Check out our FAQs or Myths of Wicking Beds for more about this).
- And while 5mm scoria can wick, it’s harder to source cleanly and often comes with excess fines.
Remember: Porous doesn’t mean wickable. Wickability depends on particle size and contact points, not just whether a material holds water.
6 Lay the Geotextile Fabric
Now that your reservoir layer is complete, it’s time to separate it from the soil — so each layer can do its job without mixing.
Geofabric (also known as landscape or filter fabric) is a porous, non-degradable material that allows water to wick upward while preventing soil from seeping down into the reservoir.
Why it’s essential
- Keeps soil and water layers cleanly separated
- Prevents soil from clogging the reservoir and plumbing
- Supports consistent wicking into the soil layer
How to Install Your Geofabric
- Lay a layer of geotextile fabric directly over the screenings.
- Once it’s roughly in place, smooth it out and ensure it covers the entire surface. A bit of overlap at the edges is fine — and if you have excess, you can even double it up for extra protection.
Note: Other materials can work here too, but they must be durable, breathable, and non-biodegradable. Avoid anything that might break down, rot, or leach chemicals in wet conditions over time.
At VEG, we use a high-quality, non-woven geotextile made from recycled consumer plastic bottles (PET). It’s safe, stable, and built to last — ideal for long-term use in buried in a wicking bed.
7 Fill with Soil & Mulch
Now it’s time to fill the top layer — the soil zone where everything grows. The right soil and mulch make all the difference in how your wicking bed performs.
What Kind of Soil Should You Use?
Choose a free-draining soil mix with low clay content. Heavy clays can compact over time and lead to poor drainage, which is the opposite of what your plants need in a wicking bed.
A good wicking bed soil will
- Be light and fluffy to help avoid becoming soggy and anaerobic.
- Contain a good amount of organic matter to support soil life and root health.
- Wick water well from below evenly
We recommend a quality vegetable garden mix — usually a blend of loam, compost, aged manure, and organic matter. Some suppliers offer special “wicking bed” potting mixes, but they’re not essential (and often overpriced).
Choosing the Right Mulch for Wicking Beds
Mulch helps regulate soil temperature, reduce evaporation, and feed soil life — all critical in a wicking bed. But not all mulches are created equal.
Top VEG-friendly mulch options
- Lucerne hay – High in nitrogen, breaks down quickly, and feeds soil microbes.
- Pea straw – Adds nutrients and organic matter and breaks down easily. You (or your chooks) might even enjoy the pea shoots.
- Sugar cane mulch – Light, easy to spread, lasts longer than the above, but has less nutrient value.
- Straw – Breaks down slower, with fewer nutrients, but still a solid choice.
- Wood chips – Less suitable for wicking beds, being best for fruit trees and perennials. It can be too heavy and coarse for seedling beds and slow to break down in veggie beds. If using, avoid green arborist mixes.
Things to keep in mind
- Go for local, organic mulch where possible — it avoids herbicide contamination, plastic packaging and reduces carbon miles.
- Some mulches (like hay) may cause allergic reactions — wear gloves and a mask if sensitive.
- Mulch can attract insects. Keep it clear of direct-seeded areas or very young seedlings.
