Australia is home to some of the world’s most innovative horticulturists, and we would rate Mark Paul – founder of The Greenwall Company – as one of our finest.
He has specialised in green walls and green roofs for over 25 years, and his design for a vertical food garden using recycled bottles provides a practical way of growing edible plants in the smallest of spaces.
This design has been used in a variety of community garden projects, and has also been utilised as a wonderful educational tool in school gardens across Australia and overseas.
Mark perfected his vertical food garden concept at his nursery in northern Sydney, where he experiments with all manner of green walls, most of which are designed as low-maintenance permanent installations.
His extensive experience with vertical gardening has taught him that edible plants need a much higher level of care than ornamental plants, which can cope with the variable moisture levels that most green walls experience.
Mark’s long-term green walls feature plants such as succulents and bromeliads, some of which can provide an edible yield; however, this is not usually substantial enough to offer anything more than novelty value.
A lightweight, freely draining, 50:50 blend of perlite and coconut coir is an ideal potting mix for this green-wall system
The popularity of growing your own food and urban farming led Mark to develop solutions to the problems of the high-maintenance requirements of edible green walls. He stresses that most edible crop plants are either too large for vertical gardens (for example, sweet corn), or demand higher levels of water and nutrients than are practical to supply in vertical installations.
Mark’s greenhouse has provided him with an environment that mimics the balcony and verandah situations that are typical for urban farmers in areas of high population density. He recommends installing a drip-irrigation system and using either controlled-release fertilisers or liquid feeding to maintain the high level of nutrition that crop plants need.
Mark suggests that perennial herbs (such as mint and thyme) are more suitable for long-term plantings, and notes that fast-growing annual crops (such as lettuce) require nutritional input every day or two to reach their full potential.
Edible green-wall gardens require a considerably higher investment in time and inputs than ornamental gardens. However, in confined spaces where horizontal space is limited, the judicious use of the sort of concepts that Mark has developed can provide a viable solution.
Make your own
This very simple system devised by Mark Paul is cheap, effective and very strong. Unlike commercial systems, which usually have fixed positions suitable for amenity plantings, Mark’s design works well with food-producing plants that vary greatly in size. It is made using the following materials and method.
Mark attaches containers to wire mesh using cable ties
Materials
- Galvanised wire mesh, 1200 by 1800 mm, 2.5 mm wire thickness
- 8 x 23 mm screw hooks
- Electric or cordless drill and appropriate drill bits
- Masonry plugs if screwing into brick, stone or concrete
- 90 x 1.25L or 2L PET bottles, washed and without caps
- Porous fabric squares cut from a material such as kitchen bench wipes
- 2.5 mm thick galvanised wire
- Metal-cutting shears or aviation snips
- Pliers
Method
1. Line up the mesh on the wall so that the long axis is horizontal, and mark the positions of the eight screw hooks – there should be four along the top, and four along the bottom.
2. Fix the eight hooks to the wall by drilling (for a wooden wall) or using a masonry bit and plugs (for a brick, stone or concrete wall).
3. Hang the mesh on the wall using the hooks. The mesh should end up hanging just a couple of centimetres off the wall.
4. Cut the bottom off each PET bottle at an angle so that the bottle ends up being about 200 millimetres in length on the long side. Then make a 3 millimetre hole in the long side.
This recycled PET bottle has various holes so that it can be hung on the wire mesh, and for drainage and aeration. Porous material is used to prevent the potting mix from falling out of the drainage hole
5. Turn one bottle upside down, plug up the hole in the neck of the bottle with fabric squares, and fill the bottle with growing medium to the top of the short side.
6. Make a small S hook with the galvanised wire, and use this to suspend the bottle in whatever position you want.
7. Repeat the process for the remaining bottles. A 1200 by 1800 millimetre piece of mesh should hold around 90 bottles.
You can make as many of these units as you like, joining them together to create larger green walls. In addition, you can use small plastic pots instead of bottles. The little pots will lean forwards a little, which looks very appealing once they are filled with lush plants.
This simple system has the advantage of allowing you to move plants around at will, depending on their size, so you can close up the spacing between smaller plants or open up the spacing between larger plants – consequently, you can maintain the overall green appearance of the wall very easily. You can also change pot sizes as required, provided that weight does not become an issue for the larger pots.
This is an edited extract from Grow Your Own by Angus Stewart and Simon Leake (Murdoch Books, RRP $45.00).
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