The ups and downs of vertical hydroponics

Hydroponic production only really came into existence in the 1930s, making a name for itself during the Second World War when it was used in the Pacific Islands to grow food for soldiers.

Afterwards, hydroponic production took off in a big way. Various methods were discovered and implemented – some more effective than others. These included the use of gravel beds and the bandolier system. “Gravel beds tend to take up space and don’t efficiently get nutrients to the plant roots,” says John Sandison, an expert hydroponic grower in KwaZulu-Natal. “So people started seeking ways to grow plants hydroponically, but in a vertical format.

Options that were tried included stacking tractor tyres or concrete blocks, but these methods failed for various reasons.” system of plastic pockets was then designed that could be hung from an overhead support. This “bandolier system” seemed promising, but it was soon found that the pockets didn’t allow enough space for the plant roots to develop properly. Plants couldn’t use nutrients to best effect. Another problem was that the plants at the bottom didn’t receive enough light, failing to grow well and producing poor-quality fruit.

Evenly spreading resources
John continues, “Light is a finite resource. In KwaZulu-Natal in summer we get roughly 650 units of light, and in winter about 450 units. Cramming plants together to give them more light isn’t going to work. vertical growing system must be cost-effective. Allow the plants to utilise nutrients efficiently and develop properly, and provide enough light from all points of the compass.”

Other versions of vertical growing systems, such as plastic pipes and plastic sausages, compact the growing medium over time. Again, this eventually stunts the plants’ roots, and deprives them of enough liquid nutrition. John says that water flow in a vertical growing system must be designed to feed plants equally from the top of the system to the bottom, and allow the even spread of light. good growing medium is also important.

Some media retain too much water while others, such as sawdust, make undesirable rivulets. However, it’s been found that pine bark chips and wood shavings are ideal. They allow liquid plant nutrients to percolate at an optimal rate from the top plants to those at the bottom. vertical hydroponic growing system shouldn’t put too much strain on its support structures in case the whole system comes crashing down. Ideally, it should be almost self-supporting. “The Verti-Gro polystyrene pots I use for growing my hydroponic strawberries place no unnecessary strain on overhead support systems", John says,  "They also allow good light and nutrient distribution from the top to bottom of each column.