Singapore’s landscape is highly urbanised and soil for growing plants is largely disturbed and consists of mostly clay with low organic matter and offers poor drainage. In edible plant gardens, raised beds offer the gardener the flexibility to concoct a more suitable soil mix that is used to grow a particular crop. The raised column of soil found in a raised bed can help to keep the roots of plants off waterlogged conditions and allows excess water to drain away. The raised bed frames prevent soil from being washed away during heavy rains.
Raised beds with concrete or brick-lined frames are preferred in Singapore as they are more durable than timber under tropical conditions. Concrete or brick-lined frames, although more durable, are also permanent. They cannot be reconfigured after they have been constructed. One major disadvantage is that the soil column in these concrete/brick-lined raised beds tends to stay wet for long periods, especially during the rainy season.
An alternative type of raised bed can be constructed. Instead of using concrete or bricks, this raised bed is framed by means of a galvanised steel wire mesh that is lined with geotextile fabric on the inside. Cable ties are used to hold the geotextile fabric in place. The thickness of the wire that make up the wire mesh will somewhat determine the shape of the raised beds that can be fashioned as it affects the ease of bending the mesh to give the desired shape.
The geotextile fabric used to make these raised beds offers an added advantage. As it is porous, it allows the column of soil to ‘breathe’. In the tropics where rain can be plentiful, excess moisture in the soil column can evaporate easier and faster in a geotextile fabric-lined raised bed versus one that is lined using thick concrete or bricks. The soil composition is also important – one can concoct a mix that is more porous with lots of coarse sand added to enhance drainage and evaporation that is necessary to reduce the likelihood of prolonged wet feet experienced by our plants.
A second advantage offered by this alternative type of raised bed is that it can be moved around when need arises, although some effort needs to be put in to empty out the soil. The height of this wire mesh raised bed can also be raised to cater to the needs elderly gardeners, people on wheelchairs and those with back issues.
The appearance of these wire mesh raised beds will confer an industrial look to the garden. Depending on the colour of the geotextile fabric, they can discolour over time. For gardeners who are not comfortable to such an appearance, you can put your creativity to use by coming up with ways to disguise and beautify the raised bed’s exterior. One of the ways employed was to plant around the raised bed. Shrubs that can grow up to the height of the raised bed can effectively obscure the exterior of the wire-mesh raised beds.