Crab Pot Mesh and Weedmat Wicking Beds are cheap, easy to build with simple home tools, and can be made in any shape or size to suit your requirements. Our designs minimise waste of mesh, plastic, and time. Despite their simplicity, they’re exceptionally durable—our beds built in 2010 still show little to no wear in 2025.

They consist of:

• a frame – made of light crab pot wire mesh 40mm x75mm, weed mat and builders’ plastic,
• a water reservoir – made from 90mm storm water drainpipe,
• an overflow – made from 13 mm poly pipe and fittings, and
• a stabilising wire – made from 10 gauge wire and a piece of garden hose.

Building Your First Bed

The instructions below will guide you through building your first set of mesh wicking beds. A 5.6m length of mesh can make three beds of 1.22m x 635mm – two 400mm high and one 300mm high. The shallow bed is suited for shallow-rooted crops such as beetroot.

The Frame

Materials for the Frame

In the photo above, as seen from left to right:

• Crab pot mesh 1.22m wide
• 4m wide builders‘ plastic used doubled up
• 1m wide weed mat
• C-clips
• (not shown) 10 Gage wire and a length of garden hose.

Tools Needed for the Frame

To assemble the frame, you will need:

• Large bolt cutter to cut the mesh
• C-clip pliers
• Small bolt cutter to cut failed C-clips
• Pair of pliers to remove those cut bits
• Tape measure
• Chalk to mark the plastic and weed mat
• Scissors to cut the plastic and weed mat
• A long straight piece of wood.

Assembling the Frame

Clipping a frame together. (We suggest working on a table and do the 300mm wall first.)

Straighten 16 rectangles of the wall, and clip a corner of the floor at the long side of the bottom plate to the first rectangle of the wall. Then clip each second rectangle to the corresponding one of the walls.

The 16^th row of these rectangles is longer than the floor plate. Bend it 90 degrees in the middle and straighten the next 8 rows. At the corner, clip it in both directions to give the bed its rigidity. Again, bend the 8^th row of these and straighten 15 rows. Bend the next 8 rows and straighten them. The last row sticks out, bend it 90 degrees and clip all 8 rectangles along the height to the corresponding ones of the first row, again for rigidity.

To bend the wire mesh neatly and with minimal effort, place the long piece of wood along the bend line and use it as a lever or straight edge – pressing or pulling against it gives you a clean, even fold without needing special tools.

The Weed Mat

Cut three lengths of 3.85m of the weed mat (250mm extra as overlap). Concertina-fold each length for ease of placement.

The mat covers the floor, one inside wall and part of the opposite outside wall in the high beds and all of it for in the low beds. Unfold these onto the frame, starting in a corner along the floor, then up and over the opposite side. At the starter corner, clip the mat in a few places along the floor and vertical side to keep it in place, and unroll it.

At the end, clip the vertical outside bit to the frame so it stays tight; the inside will be held in place by the soil. Press the corners In tight to prevent stress later.

The Plastic Liner

Cut two pieces of 1,800mm x 1,200mm plastic liner for the taller beds and one of 1,600 x 1,000 for the lower bed. Fold the sides of each piece as an envelope, the size of the bottom plate, 1,200mm x 600mm.

Place the plastic liner in the bed, unfold it while making sure the corners are vertical.

The Stabilising Wire

Cut 590mm piece of garden hose as cover for the stabilising wire, with a V at one end.

Cut a 660mm piece of 10 gauge wire and bend 30mm at one end, slide the wire through the garden hose sharply so it is 600mm long and bend the wire at the second end.

Put the stabiliser in last when everything else is in place.

The Water Reservoir

Materials Needed for the Water Reservoir

To make the water reservoir assembly, you will need:

• 90 mm PVC storm drainpipe
• 90 degree 90mm PVC bend
• 90mm mosquito screen (compulsory in Townsville and for schools, recommended elsewhere)
• 90mm PVC end cap to keep the water in and thirsty bush rats out – This comes from experience!

Tools Needed for the Water Reservoir

• A piece of lino with one straight edge, an elastic band and a pencil to mark the cuttings on the PVC pipe.
• A hacksaw to cut the PVC pipes.
• A drill, a 60mm hole-saw for the drainage holes in the PVC pipe, a 12mm drill bit to cut a hole in the PVC pipe for the overflow.
• A small pair of pliers to remove the cut-out bits from the hole-saw.
• A pair of scissors to cut the liner and the weed mat.
• A pair of nail scissors to cut the outlet hole in the liner and weed mat.
• Masking tape to hold the liner in place while filling the bed with soil.

Assembling the Water Reservoir

With a piece of lino with one straight side as shown, mark one length of 1.150mm and one 500mm of the 90mm storm drainpipe. On the long length, mark the centres of the holes, the first one at 250 mm of one end, the next two at 350mm and cut the pipes. The elbow goes at the 250mm end and the end cap goes at the other end.

Place the 90° PVC bend so that the holes in the PVC pipe reservoir face down and drill a 12mm hole 100mm above the floor level as shown above.

File this out 1mm, so the poly pipe will fit snugly.

The Overflow

Materials Needed for the Overflow

For the overflow, you will need:

• Water-tank outlet
• 13mm poly pipe: one length of 220mm and two of 50mm
• 90° 13mm poly pipe bend

Tools Needed for the Overflow

• Strong scissors or a poly pipe cutter.

Assembling the Overflow

Cut the poly pipe into one length of 220mm and two of 50 mm.

Diagonally cut one end of the 220 mm length. It is to be inserted onto the fill pipe with the opening down, so the water flows out when the water flows out when re-filling the reservoir when it is full. Cut a 20mm hole through the liner and weed mat, 950 mm from the bottom and opposite the hole in the PVC pipe.

Placing The Overflow

Unscrew the nut and one washer of the tank outlet, leaving one washer at the outside.

Push the outlet from the outside in through the 20mm hole in the weed mat and liner, and screw the nut and washer back on from the inside.

Push the uncut end of that 13mm poly pipe onto the tank outlets’ 12mm and the cut end into the fill pipe with the cut facing down.

At the outside, place the two short bits onto the 90° bend and push one end into the tank outlet. These can be swivelled to raise the water level in the bed when needed.

Soil

The volumes of the beds are respectively 288L and 216L. Allowing for 30mm freeboard for mulch, the rectangular bed needs about 270L of soil and the round bed 195L. See Mixing Your Own Healthy Soil for Wicking Boxes and Tubs to get your own healthy soil.

When filling the bed with soil, make sure that there are no corners of the lining lying flat; all the plastic must be upright against the wall. If needed use, duct tape to hold it in place – learned the hard way.

Weed Control Around the Beds

In the photo showing the overview, we covered the area below and between the beds with builders’ plastic and then weed mat. While weed seeds still germinate and grow their roots under the beds, they are easy to pull out as their roots cannot grow through the plastic.

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To function correctly, a wicking bed requires:

• A 90 mm PVC pipe to hold about half of the plant-available water below the level of the overflow pipe and the bottom of the bed. The other half is held in the open spaces between the soil particles – water that would normally drain away. 
  As the pipe fills up quickly but the open spaces only slowly, filling up a bed with an open tap to get it fully filled means coming back once or twice after water comes out of the overflow; with the tap only partly open it takes a bit more time.
• A fill pipe: from the surface into the reservoir pipe for refilling.
• An overflow pipe: An overflow pipe from the top of the reservoir pipe through the wall to the outside, to prevent beds and boxes from becoming a swamp during heavy rain or over-watering.

Common Wicking Containers

Styrofoam Boxes

Styrofoam wicking boxes can be placed on tables for easy access. They are portable, durable (lasting over ten years), and help regulate soil temperature. They are also easy to make and often available for free from greengrocers or vegetable wholesalers. (See making a Styrofoam wicking box)

Wicking Tubs

Larger pots and tubs can be converted into wicking containers by adding a plastic liner (if necessary), a 90 mm PVC reservoir pipe, a fill pipe, and an overflow. Black tubs may overheat, so surrounding them with shade cloth can help regulate temperature. Tubs can also be moved easily using a trolley.

Wicking Beds

Wicking beds are permanent structures that come in various shapes, sizes, and materials. (See the countless ways to make wicking beds for examples.)

Key Guidelines

• When building your wicking bed, it is important to keep the following essential requirements in mind.
• An overflow pipe should be fitted 100 mm from the bottom to prevent the box from swamping from excess water.
• Soil and mulch should not exceed 400 mm above the water reservoir.
• No plant should be more than 350 mm from an outlet hole in the reservoir pipe.
• A U-shaped reservoir is required for beds wider than 800 mm to ensure even water distribution.

The post The Basics of Building your own Wicking Beds appeared first on Healthy Plants - Healthy People.

Construction Materials

Wicking beds built on school grounds must be made from safe, durable materials that meet regulatory standards. All materials should be non-toxic and able to withstand long-term outdoor exposure without breaking down.

Key requirements:

• Materials must be non-toxic and suitable for outdoor use.
• Timber must be:
  • Sustainably sourced
  • Durable enough to withstand long-term outdoor exposure (7 years or more)
  • Free from rot, fungus, and pests
  • Not treated with CCA (Chromated Copper Arsenate).
• All bolts and screws must be:
  • Galvanised for weather resistance
  • Installed flush with timber surfaces to avoid injuries

Source:

• 12.5 External timber finishes and decking

The timber we suggest complies with these regulations:

• Micro PRO Sienna treated pine for logs and decking
• ACQ-treated timber for vertical joint covers
• Hardwood fence palings (which are naturally durable) to protect the liner.

Location

When selecting the location of wicking beds, regulatory compliance has to be taken into account, as well as plant health and the convenience of staff and students.

Key requirements:

• Beds must not block the view of staff or security personnel, preventing blind spots.
• The combined height of the bed and plants must allow adequate supervision of the school grounds.
• Beds should be positioned so that they cannot be climbed and present access to other areas such as walls or roofs.
• Beds must be placed in a location which receives 6–8 hours sunlight per day.
• Location of the beds must allow students to effectively reach all areas of the bed, and ensure that children don’t feel inclined to climb in.
• Hoses must be secured in a manner that prevents tripping or children from accessing them unless supervised.
• Tools should be stored safely when not in use.

Source:

• 21.1.4.1 Raised planter beds
• 7.9 Safety and security in design
• External areas | worksafe.gov.au

Growing and Plants

When growing plants in school wicking beds, the following requirements apply:

• No plants that are common allergens or produce excessive pollen or dust are to be grown.
• Plants must not create blind spots nor present a risk of causing injury if toppled and falling out of the bed.
• No fresh animal manures allowed in the beds.
• Compost, soil conditioners, mulches, potting mixes, and soils must comply with Australian Standards, including:
  • AS 4454 Compost, soil conditioners and mulches
  • AS 4419 Soils for landscaping and garden use
  • AS 3743 Potting mixes

We suggest:

• Avoid industrial chemicals to protect the soil biology and ensure long-term plant health.
• Work with your groundskeeper to ensure no chemicals are used around the wicking beds, helping to maintain the integrity of the soil and plants.

Disclaimer

The information provided on this site is for informational purposes only and is provided “as is” without any warranties or guarantees. It does not constitute legal, regulatory, or professional advice. You are responsible for ensuring compliance with your local laws and regulations. Always consult with a qualified professional regarding your specific situation.

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Wicking refers to water moving sideways and upwards without any external support due to its molecular structure. For the science-minded, wicking happens because a molecule of water has a positive and a negative end. These ends attract each other, making water molecules stick together. The power that links the molecules is not very strong, but is sufficient to pull the water up to 30cm.

Good soil, cloth, and other materials contain countless small channels called capillaries. These very small and connected channels make it possible for water to move up and sideways. Without them, or if they are blocked, wicking cannot happen. To see this in action, hang a wet towel half in and half out of a bucket of water, and watch as water slowly drips onto the surface. Wicking in soil works similarly but at a slower rate.

In some soils, wicking can draw water upwards to 300cm. This allows for a reservoir of water inside beds or boxes, enabling bottom-up watering in addition to the traditional surface-down method.

What Are Wicking Beds and Boxes?

Wicking beds and boxes are the containers we use to grow plants in a way which maximises water efficiency and provides an environment for optimal growth. They are waterproof or lined with a waterproof liner and have an overflow to allow for excess water to drain out. At the bottom of the container is a pipe filled with water that, with the surrounding soil, forms a reservoir of water that will wick up and water the roots. There is an overflow at the top of the pipe to drain excess water from rain or over-watering.

Advantages

Wicking beds and boxes offer numerous benefits:

• Suitable for many more locations as they can be placed near trees, on heavy clay soils, concrete, balconies, or even tables.
• A built-in water reservoir provides plants with consistent moisture over longer periods, reducing the need for frequent shallow watering as the water is stored in the root zone. This encourages root development and, with proper nutrition, ensures healthy soil and plants. (See our guide to making your own healthy soil)
• Optimised water use as they are self-contained; no water percolates below the box and tree roots cannot invade the beds. Over-watering is prevented by the overflow.
• Less frequent watering makes it a convenient weekend task, especially for busy individuals.

Warnings

Since we introduced wicking beds online 20+ years ago, several incorrect designs have emerged. To avoid these pitfalls, refer to our article on common misconceptions and wrong designs.

One major issue is designs that use stones and cloth to separate soil from the 90 mm PVC pipe. This approach is flawed because:

• The cloth creates an airlock, preventing wicking (air does not wick).
• Stones replace essential soil biology, which is crucial for plant health.
• Water-holding capacity is reduced.

For a detailed explanation of why these designs are ineffective, see the real cost of using cloth and stones in wicking boxes and beds. Disappointingly, even the ABC has promoted these flawed designs.

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Healthy Soil-Biology is Essential for Healthy Plants

Soil-Biology refers to the viruses, bacteria, archaea, fungi, algae, slime moulds, protozoa, and nematodes which feed the plants and create many compounds the plants require for healthy growth.

Stones lack the large surface area needed by the soil-biology

The Soil-Biology needs surfaces to attach themselves to and countless hidey-holes for protection. Stones are solid without hidey-holes and provide a very limited surface area. A spoonful of clay when spread out has far greater surface —equivalent to the size of a tennis court. Because of this, using stones in a wicking bed is a waste of space that should instead be occupied by nutrient-rich soil, home to a vibrant soil biology.

Cloth Will Create Airlocks and Stop Wicking

Some people add cloth to cover the reservoir and stones to prevent soil from washing into the reservoir pipe. This is not an issue in properly made wicking beds, where the holes on the reservoir pipes point downwards.

The fine roots can penetrate the cloth and larger roots grow around it to reach the water. As the water level drops, this space is filled with air as it moves in to replace the water. Air does not wick water, and this creates an airlock between the cloth and the water.

The bed above the cloth ends up like a reduced regular garden bed. It has a permanent water supply at the bottom, rather than wicking soil, and the space below the cloth has no soil biology.
As the water becomes permanent, it can become a haven for mosquito larvae. In a wicking bed the reservoir pipe is surrounded by soil and there is no permanent water as it gets used within days.

In the photos below, we show a simple demonstration of the wicking effect on the left and the lack of it on the right.

The pipe with only soil (left) was able to wick water up 35cm in 24 hours (and further) but the pipe with stones and cloth (right) failed to wick. In the photo above, it is clear how the air gap caused by using cloth and stones prevents wicking.

Soil Holds More Water than Sand or Stones

A good soil mix retains more water than the same volume of stones, coarse sand, pebbles, or fine sand. To demonstrate this, one-litre samples of soil, stones, and sand were dried in the hot sun, weighed, soaked, and then measured again to determine how much water they held.

Since a gram of water is equal to one millilitre, the difference tells us how much water there is in each litre of soil. In the tables below, ‘Inert material’ refers to rocks, stones, sand, loam, and clay.

As the soils in our beds vary a lot, we first took one litre of soil from three beds, filled each container with water, drained the free water out and weighed it wet. We then spread the soil out on a table, let it dry in the sun and weighed it again in the container.

Average Soil Mix

We used the average of those three samples from the table above in the table below. We then filled four containers, with respectively stones, coarse sand, pebbles and fine sand. As with the soils, we filled them with water, drained that, spread the content out to dry in the hot sun, put it back into their containers and weighed those again.

Comparison of the Five Materials

Conclusion

Our soil mix held more water than stones, which held more than pebbles or sand. Much of that water is normally held in the bodies of the soil biology. For suggestions to improve your soils and stimulate your soil biology to grow, see our guide to create and improve your own soil.

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Styrofoam Boxes

Styrofoam boxes of all sizes can be turned into wicking beds, from 50-litre boxes to 13-litre mini versions using 40 mm PVC pipe as a reservoir. These can be decorated and placed on tables for convenience.

If you want to make your own, check out our guide on making a Styrofoam Wicking Box.

Commercial Wicking Beds

Some commercial wicking beds suffer from the two common misconceptions of wicking bed designs and isolate the soil from the water reservoir. Luckily, many of these beds can be converted to fully functioning beds simply by removing the plastic or fabric separator and stones. Designs that use Wicking Cells as above (where soil is allowed to reach down into the water reservoir) are acceptable.

Designs that separate the soil and the water, typically using stones or plastic risers, are not true wicking beds.

Drums

Metal and plastic drums (876 mm high, 597 mm diameter) can be cut to 400 mm high to match the maximum wicking height of 350 mm. Use food-grade barrels or thoroughly clean them.

A proper setup includes the drum, a fill pipe, a reservoir, and a 12 mm poly overflow pipe sealed into the wall with silicone. Avoid vertical cuts across the diameter, as they reduce soil space and require extra support structures.

Avoid vertical cuts across the diameter, as shown in the photo below. This requires extra support structures and thus cost. The ones on the photo have no overflow to drain excess watering and heavy rain. They are a swamp waiting to happen.

When cut to 400 mm high, all they need is the fill pipe, the reservoir and a 12 mm poly overflow from the reservoir through the wall, with the joint sealed with silicone.

Wire Mesh and Weed Mat

Inexpensive wicking beds can be made using wire mesh and weed mat, requiring minimal tools: a wire cutter, C-clips, and scissors. The example below is made with 80 mm x 50 mm mesh and 1m wide weed mat. They can be made to almost any size and shape.

Plastic Containers and Tubs

Plastic containers and tubs work well as wicking beds. If you are using black containers, cover the outside with double shade cloth to keep them cool.

Cut a reservoir pipe to fit the tub, a fill pipe and a short length of poly pipe for the overflow, as shown in making a Styrofoam wicking box. Place the reservoir in the tub, drill a 12mm hole 85mm from the bottom and press the 12mm Poly overflow through the wall into the reservoir pipe. Then silica it in place. (The photo shows no overflow, which could lead to turning into a swamp during heavy rain or accidental over-watering.)

Concrete Tubs and Bathtubs

Concrete tubs and old bathtubs can be easily converted into wicking beds. An 80 mm outlet of 40 mm PVC pipe is sealed into the plug hole using silicone. A corresponding hole in the reservoir pipe is to be positioned over it.

One key difference when making them in this manner, is that your overflow is inside the reservoir pipe and one outlet hole in the reservoir hole is placed exactly over the drainage hole of the concrete tub. The other end of the reservoir pipe is sealed with an end cap or duct tape. In Bathtubs the overflow is the same, but the reservoir pipe is the length of the bath with several outlet holes no more than 70cm apart.

Galvanised Iron

Large galvanised iron containers make great wicking beds. A poly overflow pipe in a U-shape runs between the liner and the wall, then under the wall and back up to100mm above ground level.

In a round bed, the reservoir is made in a U-shape to ensure that no plant is more than 35cm from an outlet hole

Sleepers

When using sleepers, reinforcement should be on the outside to keep the inside smooth and prevent damage to the liner.

See our guide on Building Wicking Beds for Schools for more details.

1,000 Litre Pods Cut in Half

Large 1,000-litre water pods can be cut in half and placed under shade for efficient wicking beds. Make sure to only use pods that have not been used for dangerous chemicals.

To store more water and ensure no plant is more than 35cm from an outlet, the reservoir pipe can be made in a U-shape.

Even Old Leaky Boats

An old boat can be converted into a mobile wicking bed. The bow is lowered, the stern raised, and the bungs removed to allow excess water drainage when it rains. This setup is ideal for renters who want to take their wicking bed with them when they move.

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We started our business off by selling seedlings we bought and raised
for several months during school. We made recycled newspaper pots to
grow them in and we started a roster for watering.

After a few months we sold a heap of these little seedlings to people
who wanted to start their own little garden. We raised 100 dollars in
that fundraiser but we need some more support which is why we are
selling these huge lemons for 1 dollar each. With all the support we get
we are going to help all the year 6’s to camp in Tallebudgera.

This was written by a one of the students participating in the project. We also asked their teacher for their comments:

The project to raise seedlings was designed and run by year 6. During planning they came up with every aspect of growing: ‘Where to get seedlings’, ‘What to put them in?’, ‘Where to place them?’ (as you can see: in the classroom – outside some naughty kids or animals might harm them), ‘What to sell them for?’, ‘How to get the seedlings home safely?’ and of course ‘Who should look after them and water them?’.

The project to raise seedlings was designed and run by a year 6 student.

During planning they came up with every aspect of growing: ‘Where to get seedlings?’, ‘What to put them in?’, ‘Where to place them?’ (as you can see: in the classroom – outside some naughty kids or animals might harm them), ‘What to sell them for?’, ‘How to get the seedlings home safely?’ and of course ‘Who should look after them and water them?’.

Wicking Beds Are a Useful Teaching Tool

Wicking beds are a great way for schools to get students involved in gardening. They make growing plants easier and more accessible, helping students learn about nature while taking care of their own crops. With low maintenance and high success rates, wicking beds keep students engaged and excited about growing food.

The students at this school have had great success with wicking beds in the past, producing enough harvest for them to take some home over the Christmas holidays. They later decided to plant the second bed with sunflowers.

If you’re interested in creating your own school wicking beds, check out our article on building wicking beds for schools.

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In this article, we show how to build wicking beds that complies with school regulations but are just as productive and toxin free when used in home gardens and small commercial businesses. While it may seem complex at first, they are easy to build and can be assembled by two people in a few hours.

These designs were developed in consultation with local teachers and school staff to ensure they are suitable for outdoor classes and school requirements. Their input helped shape a design that is safe, durable, and easy for students to work with across multiple age groups.

Design Considerations

The materials we have used are safe and non-toxic. Pay attention when picking your timber to not use anything treated with CCA (Chromated Copper Arsenate) or LOSP (Light Organic Solvent Preservative). All timber used should be treated with ACQ (Alkaline Copper Quaternary) or MicroPro® Micronized Copper Azole (MCA).

The bed can be packaged into a kit and prepared offsite. By doing most of the work offsite, it’s possible to quickly and easily set the bed up at its location. This has encouraged service organisations, PNC’s and individuals to donate them to local schools. When prepared as a kit, it is essential that you dont pierce the liner until it is installed at its final destination. It is near impossible to realign the holes in the liner and the frame once moved and installed.

Selecting your bed design

We have three bed designs, each suitable for different purposes. All the beds are 40cm high. Click on the diagrams below to enlarge.

The first is the Long Narrow Bed, this is best for primary schools as it allows even small kids to reach the centre. It is large enough to allow a half or more of a class to surround the bed. It’s also the simplest of the three designs.

Next up we have the Long Wide Bed, this is better suited to older kids and adults. It’s large enough to grow a greater diversity of vegetables and gives you plenty of space to work with.

Finally, we have the Square Bed. This works best for projects, allowing you to give a group of students the responsibility of taking care of a crop from preparing the soil to harvesting.

Involving the Groundskeeper

Try to get the groundskeeper involved and keep them informed. They can provide valuable knowledge and assistance, and can help to prevent costly mistakes. If you’re lucky, they may also look after your bed over the holidays!

Keeping the groundskeeper informed from the start helps to ensure the beds remain free from accidental sprays. It can also we can also prevent time-consuming mistakes like the time a well-meaning groundskeeper folded down the liner walling the bed and then filled it, resulting in needing to dig out the bed and pull the liner back up to allow the bed to hold water again!

Picking the right location

When choosing a site, consider the location with care.

The site will need at least six hours of sunlight during the winter and avoid shade from trees and buildings. The ground should be level and free of large rocks and sharp objects. The site should not be too windy, avoid area’s such as wind tunnels.

The location should be easily accessible, and the beds should be given sufficient space to allow the students to surround them. There should be easy access to a tap. Think ahead and plan out where the bed’s outlets will be to prevent the overflow from making the ground a slippery swamp.

Preparing the ground

If nut grass or other aggressive plants are present that may penetrate the liner, place a metal sheet or other hard barrier under the bed to prevent future leaks.

Clear away all sharp objects, including sticks, roots, and debris that could puncture the liner and then level the ground carefully to create a smooth, even base.

Materials and Equipment

All materials required are available from your local hardware or garden store, and common household tools are all that is needed to build the beds. Make sure to measure twice, cut once. We learned the hard way.

Checklists with all the materials and site requirements are available at the end of this article. We have separate documents for each design.

Schools have strict legal requirements on what materials can be used, so make sure that everything complies with school regulations. It is essential that all timber used should be treated with ACQ (Alkaline Copper Quaternary) or MicroPro® Micronized Copper Azole (MCA).

The Frame

The frame consists of two layers of sleepers held together with four wooden uprights, fastened with heavy-duty countersunk screws.

Timber

Use Micro PRO Sienna treated pine, available in sleepers of 2.4 m x 20 cm x 5 cm.

• Long Narrow Bed Six sleepers of 2.4 m in total. One sleeper is cut into three 0.8 m pieces, and the other sleeper is cut into an 0.8 m length leaving a spare 1.6 m offcut.
• Long Wide Bed Six sleepers of 2.4 m in total. Two of the sleepers are cut into lengths of 1.2 m resulting in a total of four 1.2 m sleepers.
• Square Bed Four sleepers of 2.4 m in total. Each sleeper is cut in half to form eight 1.2 m sleepers.

Always measure your sleepers before leaving the store. Even when listed as 2.4 m, lengths can sometimes be slightly longer than described.

Many hardware stores, such as Bunnings, offer a cutting service. The first cut is free, and additional cuts typically cost a dollar per cut. This can make transport much easier and save you time and effort on site. The Bunnings order form below already contains the specifications. After the store cuts the sleepers, measure them again to ensure they match your required dimensions before you leave. Delivery services are also available if transporting long materials is difficult.

You will also need four lengths of 40 cm ACQ-treated decking timber to give vertical structural strength. This is typically about 9 cm wide and 2 cm thick.

Fasteners

The screws must be weather treated and countersunk to avoid injuries.

You will need:

• 16 batten screws (18-8 × 100 mm) that hold the battens together
• 32 screws (10-8 × 40 mm) to connect the uprights to the battens.

The Liner

To make the bed watertight, use Concrete Underlay AS 2870 (200-micron, 2 m wide rolls when folded, or 4 m wide when unfolded). It should be folded over and used doubled up for extra thickness and durability, this acts as insurance against leaks. When purchasing, we prefer using the rolls that are already doubled up such as the example linked above. It should cover the floor and all four sides of the bed.

Look for a store that allows you to buy it by the meter, as full rolls can be quite expensive and are too large for our needs. Make sure to check the packaging for holes or damages before purchase.

The Water Reservoir

Apart from during heatwaves, the reservoir holds enough water for up to a week for the plants to grow, which makes watering mostly a weekend job. Connecting the overflow directly into the reservoir prevents it clogging up during heavy rainfall and thus the bed turning into a quagmire.

Pipe and Connections

Both the fill pipe and storage pipe(s) are 90 mm PVC Stormwater Pipe:

• Long Narrow Bed
  One length of 0.5 m
  One length of 2.1 m
  One elbow
• Long Wide Bed
  Two lengths of 0.5 m
  Two lengths of 2.1 m
  Three elbows
• Square Bed
  Two lengths of 0.5 m
  Two lengths of 0.8 m
  Three elbows

All the beds will additionally need:

• One end cap
• One screen cap (this prevents objects being dropped into the reservoir and stops mosquitoes, frogs and other small wildlife getting in. It is required in Townsville.)

The Overflow

The overflow allows excess water to drain from the bed. By connecting the overflow to the reservoir directly, we eliminate the risk of the overflow clogging, keeping the bed safe even during heavy rainfall.

• GD Watermark 15mm Female Tank Access Outlet
• Toro 13mm Tail x 15mm BSP Male Director

Tools

You will need an electric drill with:

• 60 mm hole-saw (to cut the drainage holes in the PVC pipe)
• 22 mm drill bit (to cut the outlet hole in the timber)
• 12 mm drill bit (to cut a hole in the PVC pipe)
• 6 mm drill bit (to predrill holes for the screws when assembling the timber frame).

A method to sand the corners of the sleepers, such as a flat or belt sander (80 grit).

Various hand tools such as:

• A small pair of pliers (to remove the cut-out bits from the hole-saw).
• A screwdriver (to put the frame together).
• A rats-tail rasp (to widen the 12 mm outlet hole in the fill-pipe to 13 mm).
• A pair of scissors (to cut the liner).
• A pair of nail scissors (to cut the outlet hole in the liner).
• Clamps or duct tape (to hold the liner in place while filling the bed with soil).
• A hacksaw (to cut the PVC pipes).
• A permanent marker (to mark where to cut)
• A tape measure (to measure the pipe and sleepers)

Building the Bed

The bed can be built both onsite directly, or prepared into a kit allowing for it be put together elsewhere in under two hours. When preparing as a kit, make sure to not pierce the liner until it is at its final destination.

Before heading out to install the bed, double check that you have all your tools and everything else you need (we know from experience). When you arrive, check that the site is still in a good condition for building.

Checklists with all the materials and site requirements is available at the bottom of this article.

Assembling the frame

To ensure that all the sleepers are cut to the correct lengths, lay the sleepers out on the ground so that the lengths match the diagrams from above.

Label each of the eight sleepers, marking each sleeper with its position (upper layer or lower layer) and the side (front, back, left or right as it relates to the diagrams below). An example of the appropriate labels is shown below in diagram 4.

Take the Lower Left sleeper and mark and drill a 22mm hole. Depending on the size of bed, you will have a different location to drill.

On Long Wide Beds or Square Beds, the hole should be 0.3m from the right edge and 9cm above the bottom edge.

On Long Narrow Beds, the hole should be in the centre (or 0.4m from the side) and 9cm above the bottom edge.

Take the Lower sleepers and place them in their respective positions as shown. The sleepers on the left and right should have their ends butted up against the sides of the front and back sleepers.

Measure and adjust the distance between opposite corners until they are the same and the sides of the bed are parallel. This ensures that the corners are square.

Screw in 2 x 100mm batten screws for each corner of the bed. Screw in through the front and back battens into the side battens placing the screws 5cm from the top and bottom edges.
Repeat the process with the Upper sleepers, and place them on top of the first layer.

The 400 mm long, 90 mm wide planks secure the two courses so they are firmly connected and prevent the top layer from sliding sideways. Use eight 10-8 × 40 mm fasteners per securing plank, as shown in the diagram below.

We found that pre-drilling is not necessary. However, when drilling into the side of a sleeper, it can help to pre-drill a hole with a small drill bit about half the length of the fastener. Do not pre-drill into the cut end, as the screw runs parallel to the wood fibres and will already have less grip.

Use a sander to round the edges.

Adding the liner

Ensure the liner is cut to size and folded over into its doubled up state. For those who have done origami, the steps below may feel familiar. If you are having trouble understanding, we have demonstrated the folds in the slider below.

Fold over the long sides by 40cm, pressing hard to get a good crease. The lengthwise folding must be done first so that, when opened, the excess liner in the corners will sit against the long side and not be in the way for the overflow.

Fold over the short sides by 40cm, once again pressing hard to make a crease. Fold each corner in, crease hard, then unfold them, we will use these creases later to help fold the plastic into its final position.

Lift the liner into the bed. It should cover the entire bottom of the bed.

Fold up the short edge against the side of the bed. Use pieces of duck tape to hold it up. Unfold the long edge, tucking a triangle of the plastic against the outside long edge.

We have demonstrated the appropriate folds below on a piece of paper. You’ll know you have it right when the liner can be pressed tight against the timber, the liner is not stretched, its corners are supported and there is a right angled triangle of excess is against the long edge of the wood.

Assembling the Water Reservoir

The water reservoir holds the water in the bottom of the bed while still allowing it to be filled rapidly using the fill pipe and it facilitates drainage to prevent the bed flooding during heavy rain.

Cut the pipes to the sizes mentioned for your bed in the materials section. There are many ways to cut the pipe, the cuts don’t have to be perfect. It may be possible get the pipes pre-cut, the Bunnings order form below contains the specifications.

Click here for a quick guide to cutting the pipe at home

Tie the pipe onto a table with bungee cords at each end of the table and mark where to cut it, using a tape measure held by the bungee cords.

At each mark, wrap the straight edge of the piece of lino or paper tightly around the pipe so it forms a circle and mark that circle around the pipe with a pencil. When cutting with a hacksaw, roll the pipe towards you and follow that circle. The cuts don’t have to be perfect, but smoothing them with sandpaper will make it easier to push them into the bends.

Depending on the type of bed, the reservoir assembly is slightly different. The long narrow bed has a single pipe and the Long Wide and Square beds use a U shaped layout.

All of the pipes longer than 50cm, need to have holes drilled along the length of the pipe. The holes should be spaced 30cm apart and be at least 15cm away from the ends of the pipe. Mark out the locations and use a 60mm drill bit (no larger or smaller) to drill the holes. When installing the pipe, make sure the holes face down.

Click here for a quick guide to drilling the pipe

Strap the length(s) of pipe to the table with bungee cords at both ends of the pipe. Then mark the centre of the first outlet at 15 cm from one end and the centres of the other holes at 30 cm apart.

Drill the first outlet hole and slide this under a bungee cord to prevent the pipe rolling somewhat and drill the other holes at the marked spots.

All beds use the same Fill Pipe Assembly and Overflow.

Assembling the Fill Pipe

To assemble the fill pipe, attach the mesh filter to one end of the 50 cm pipe and a 90-degree elbow to the other end. This is the upright pipe you will fill the bed with.

The 90 degree elbow attached to the fill pipe will need a 22mm hole drilled, this will be done when setting up the overflow.

Assembling the single pipe layout

For the long narrow bed, attach an end cap to one end of the 2.1 m pipe and connect the fill pipe assembly’s 90-degree joint to the other end. When installing it in the bed, support the pipe so the fill pipe points upward. Once the bed is filled with soil, the pipe will remain stable.

Assembling the U shaped layout

For the long wide bed and the square bed, attach a 90-degree elbow to each end of the 50 cm pipe. Then attach the long pipe segments (2.1 m for long wide beds, 0.8 m for square beds) to each elbow so the pipes form a U-shape lying flat.

With the U-shape open side facing up, place an end cap on the right pipe and attach the fill pipe assembly to the left pipe, with the fill pipe pointing upward.

Putting it all together

By this stage, the bed should already be in its final position with the liner installed. Begin by marking and then cutting or piercing a hole in the liner that aligns with the overflow hole in the bottom left sleeper. You can easily make the hole by stabbing with a screwdriver through the hole in the sleeper from the outside, resulting in a small hole in the liner. You can then use a small pair of scissors to cut the hole to size.

The overflow is one of the most important parts of the bed, so take care when installing it. Insert the tank fitting through the hole in the sleeper and the liner, then secure it firmly. The male threaded end of the tank fitting should be pointing into the bed.

Onto the outward facing end, screw on the male director fitting.

Next, place the reservoir assembly you prepared earlier into the bed. With it in position, mark the spot on the fill pipe elbow where a hole will need to be drilled. This location should line up with the part of the overflow sticking into of the bed. When the hole is drilled, the overflow pipe should slide into the fill pipe without lifting the pipe off the ground.

Remove the reservoir assembly from the bed again and detach the fill pipe section for now. Drill a 22 mm hole in the fill pipe elbow at the marked spot. Once this is done, reattach the fill pipe to the reservoir assembly.

Finally, place the reservoir back into the bed. The hole in the fill pipe elbow should now align with the overflow, allowing the pipe to slot neatly onto the overflow fitting. You will need to support the upright pipe until the bed is filled with soil.

Tips when building offsite

When making kits and building offsite, don’t pierce the liner until you reach the final destination!

Once the liner has been pierced, it is almost impossible to realign the holes if the bed or liner is moved. For this reason, do not make any holes in the liner until it is assembled in its final destination.

If the bed ever needs to be relocated, a new liner will need to be prepared.

Finishing the Bed

Once assembled, the bed will need to be filled with soil to the top of the bed. The soil is expected to settle and the airspace above is used for mulch. The amount of soil varies depending on the type of bed is shown below.

To give an idea on how much soil is needed, the average wheelbarrow load is between 85 to 100L. To learn how to make your own soil, check out our guide to Mixing Your Own Healthy Soil for Wicking Boxes and Tubs.

Once the bed is filled with soil, fill the reservoir till it starts overflowing. Then water the bed from the top till it starts overflowing again, using the “shower” setting on the hand piece to ensure it is a gentle rain. This will wet the soil and provide the right compaction to ensure that wicking will happen.

It may take a surprising amount of water and take a long time to fill.

Final Step

About a month later, once the bed has fully settled, cut the liner just at or below the soil level of the bed. This keeps the bed looking neat and protects the liner from solar deterioration.

Maintaining the Bed

Don’t leave the bed empty when not in use, plant a green manure crop instead. This is especially important if the bed will be unattended over the holidays or for an extended period. Keeping it planted prevents the soil from drying out and helps maintain its soil biology and structure.

Checklists & Order Forms

Coming Soon!

The post How to make school wicking beds, suitable for all age groups appeared first on Healthy Plants - Healthy People.

Misconception 1: Soil Filling the Reservoir

Some believe that rain or excess surface watering will cause soil to fill the water reservoir. This only happens if the outlet holes of the reservoir pipe face upwards. When properly positioned downward, water moves through soil too slowly to carry soil particles into the reservoir.

Through years of testing and examining dozens of wicking boxes—some exposed to heavy rain and the floods in 2011 and 2013—only a few contained small amounts of soil in the reservoir pipe, and even then, just a handful.

While some designs use cloth to separate the soil from the reservoir, this disrupts the wicking process. Plant roots can still grow between the bed walls and the lining to access water, which lowers the water table and creates an air gap. Since air does not wick, the wicking action stops entirely.

Misconception 2: Water-Logging

There is a common but unfounded fear that wicking beds will become waterlogged. However, water in the bottom layer (below the overflow level) does not remain stagnant for long. Transpiration from plants and evaporation from the surface quickly draw water up, allowing air with oxygen to return to the lower layers. Even in the absence of plants, natural evaporation is sufficient to prevent water logging.

Many designs incorporate stones in the bottom layer, but in addition to creating an airlock this is ineffective for two more reasons:

• Stones do not store water, and the open spaces between them lack capillaries, meaning they do not wick.
• This wasted space should instead be filled with soil, which holds more water and supports beneficial soil biology. While this may sound counter-intuitive, we have tested this, and you can check the results in our article on the real costs of using cloth and stones in wicking boxes and beds.

We hope by understanding these design flaws and avoiding common misconceptions, you can create a truly effective wicking bed that functions as intended. If you want to learn about how to improve your soil (particularly in cases of sandy soil), read our guide to making your own healthy soil.

The post Consequences of Misconceptions in Wicking Bed Designs appeared first on Healthy Plants - Healthy People.

Be aware that there are on the Internet a lot of guides about making wicking beds that are flawed – even on the ABC – as explained in common misconceptions and design flaws of commercialised and popularised wicking beds.

Materials

• Watertight box of any size. The example uses a 30 litre broccoli box made of Styrofoam.
• A length of 90 mm storm drainpipe (PVC pipe) long enough to go across the long edge of your box.
• 500 mm of 40 mm PVC pipe
• 90 mm of mosquito screen
• Duct tape
• Where pardalotes are present, a strip of shade cloth.

Getting Started

Once all the materials on hand, please read through the instructions in advance to prepare the bits and put them together.

Preparing the Box

Drill a 10 mm hole in the centre of a short side of the box, 95 mm from the bottom edge, so it opens directly into the top of the reservoir pipe. This prevents them from being clogged up by worms. The 10 mm size keeps cane toads out, as larger holes allow small ones to enter. The box can be painted and made a bit more attractive. The green boxes above were made by a girl guide to get a gardening badge.

Cutting the Pipes

Cut a 90 mm PVC drainpipe to fit lengthwise inside the box, this will be the water reservoir pipe. Measure carefully, as box sizes can vary in wall thickness and some may be tapered at the base. If needed, cut wedges from the ends of the pipe to ensure it sits flat at the bottom.

Cut two 60 mm holes in the water reservoir pipe, positioning the centres 150 mm from each end. On the opposite side of these large holes, cut a 40 mm hole for the fill pipe, positioned about 70 mm from one end. Take care to ensure the hole is drilled on the opposite edge so that the 60 mm holes face straight down. Cover the end of the pipe at opposite of the overflow with duct tape to prevent soil from washing in.

Cut a 500 mm piece of 40 mm PVC pipe and insert it into its hole in the water storage pipe. Use a round file or sandpaper to ensure a snug fit, if necessary.

Putting it All Together

Place the water storage pipe in the box with the large holes facing the bottom. Position the fill pipe opposite the drain hole. Attach mosquito screen to the end of the fill pipe to keep mosquitoes and other small creatures out of the reservoir.

While filling the box with soil, pack some of it behind the closed end to ensure the open end fits snugly against the side of the box. For soil recommendations, see our guide to making your own healthy soil.

Before planting your first seedling, saturate the box by filling the reservoir with water, then water from the top until water begins to flow out of the overflow. A 30-litre box may need about 5 litres of water.

Cover the front of the boxes with shade cloth to protect them from pardalotes. While they help control caterpillars and aphids, pardalotes tend to enlarge the outlet hole to build nests inside the box — something learned the hard way!

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