AN INTRODUCTION TO

WICKING BEDS

Presenter:Cally Brennan (aka ‘The Wicking Witch of the West’)

Canberra Permaculture Design

PermablitzACT

About me:

• Live in Cook with partner Jeremy, toddler Sophie, and dogs Cassie and Kiki

• Been gardening since I was small

• Completed Permaculture Design Certificate in 2011

• PermablitzACTcoordinator for 2 years

• I hate watering – have been experimenting with wicking pots and beds for over 4 years

Today’s presentation will cover

• The concept of wicking

• Basic wicking bed design

• Examples from my garden and beyond

• Relevance to urban agriculture – how wicking beds

enable more intensive land cultivation

• Pros and cons

• Measuring performance and further research

The concept of wicking

• Water can flow upwards!

• (You need a medium for the water to move through)

• Water can wick upwards about 30cm through soil

• So if you place water at the bottom of a plant pot in

contact with the soil, then it will wick up through that soil

• If you can send water directly to the bottom of the pot, then watering is most efficient (you avoid the

evaporation that comes from watering at the surface)

Wicking bed = a very efficient way to grow plants with high water requirements• Need to water less

often

• Constant access to

‘underground’ reservoir

or aquifer makes plants more resilient in

heatwaves

• Especially good for

vegetables, but even trees seem to thrive in

them.

The basic design of a wicking bed

Common media used in wicking beds

Reservoir

• Anything porous that can hold and wick water while supporting growing medium above - gravel, scoria, clay beads, broken terracotta, bricks, woodchips/coarse mulch, even the growing medium itself if it’s porous enough.

Growing medium

• Anything nutrient-rich, light and friable – compost, composted horse manure (lots of sawdust), coconut fibre (rot it down first), mushroom compost (check pH), good potting mix, coarse sand (add to improve drainage), worms (great for aeration)

Examples: wicking containers can be large or small

and can be made from…

Recycled polystyrene vegetable and fish

boxes

Converted regular plant pots

Even old bathtubs…

Buckets

(a very cheap instant wicking garden)

From small plastic storage

containers…

… to large wooden raised beds, lined with plastic

(we used recycled sections of fence palings for this one)

Old fibreglass containers, repainted,

repurposed and connected together on

our verge

(one watering pipe for all beds)

Relevance for urban agriculture

Wicking beds let us use land more intensively than we could otherwise:

1. Growing in inhospitable places

They enable us to grow edibles in places where these plants would not survive in the ground (or where there is no soil – concrete, pavers)

2. Growing in close proximity

They allow us to grow vegetables in close proximity to other plants with different needs (e.g. fruit trees) without direct competition.

The above may also be true of other types of container gardens, BUT wicking beds need a lot less watering.

Example: Growing edibles where they would not survive in the ground

Location: dry, compacted clay, next to

large gum tree. Strong westerly sun.

Size – 1.5m x 3m. Yield over 1 year:• 9 small butternut pumpkins, • about 10 large eggplants, • 10 Hungarian peppers,

• several bowls of broad beans, • too many chilli peppers to count, • a bowl of cape gooseberries,

Watering: once every 1 to 2 weeks in

the hottest part of summer (none

needed in winter)

Example: Growing plants with different needs close together

This ‘pod’ grows cabbages next to

establishing fruit trees.

• Cabbages need a lot more water and

fertiliser than the trees.

• The cabbages get their own water

and nutrients; overflow goes to the

trees.

• The young trees are protected from

competition; no root disturbance from

having temporary crops in the same

soil.

Pros and Cons

Cons

• They are very heavy

• Large beds can be time consuming to build

• Fittings can be fiddly and expensive

• Like all container

gardens, soil can get exhausted

• Potential for salt build up in some areas

Pros

• Can be made cheaply

• Use up waste containers (old baths, sinks, apple crates, water tanks, polystyrene etc.)

• Not always big or complicated

• Very low maintenance

• Grow things almost anywhere

• Can incorporate worm farms to supply nutrients

• Beds can be designed for periodic draining if salt is an issue

• Your plants don’t die when you go on holiday

Measuring performance – quantifying benefits

We know wicking beds are highly water efficient.

But we could do with a lot more research on:

• Comparing yields per m2 from wicking beds with agricultural yields of the same crop in the ground under similar conditions

• Comparing yield and water needs between wicking beds and conventional raised beds

• Comparing plant growth with aquaponics systems

• Testing whether salt build up occurs under normal conditions

• Analysing performance over time, especially with perennial crops

• Comparing the effects of different growing and reservoir media on plant growth and resilience

• Short and long term effects of additions like integrated worm farms, biochar, and beneficial microbes

How measurement, quantification and research can help

We need more information to help us to make the best decisions about:

• The optimal ratio of reservoir height to growing medium height

• The best places to use wicking beds, and where other technologies would be more appropriate

• How to keep them fertile over long term without importing fertilisers

• How to get the best yields out of them

• Which plants do best in them

• How to integrate them within perennial food forest designs