Different hydroponic methods

We investigated the different methods of hydroponics constrained by several factors. We needed the roots to grow quickly, they should be visible, and the method used should allow for many different root growth shapes to be created.

In order to determine the best possible method, we visited the key supplier of hydroponics in the Wellington region, the Switched on Gardener (SOG) in Ngaio gorge. The experts at SOG provided us with three different options, deep water culture, aeroponics, and flood and drain subirrigation. Each of these methods were then investigated further.

Deep Water CultureDeep water culture keeps the plants constantly suspended in nutrient enriched water. This common method was not used as there can often be large amounts of algae growth in the water which will inhibit the ability to view the roots as they grow.

AeroponicsAeroponics keeps the roots of a suspended plant saturated in a fine mist of nutrient enriched water. This method has several key benefits and promotes a much higher growth rate due to the high amount of available oxygen. The resultant plants have an 80% increase in dry weight biomass, however the algae growth in the environment is high which would considerably reduce the visibility of the root growth.

Flood and drain subirrigationIn this hydroponic method the nutrient enriched water is periodically flooded over the roots. This process provides some of the benefits of Aeroponics, but considerably reduces algal growth and was therefore selected as the preferred method.

A flood cycle period of 15 minutes flood every 3 hours was suggested by the experts at SOG, this cycle was adjusted slightly in order to find a good balance between, the best growth without drying out the plants, the least algae growth, and a good level of water oxygenation.