The Hydroponic Flytrap - Flood & Flow Technique

In an earlier blog Tim Bailey, Newsletter and Journal Editor for the Carnivorous Plant Society, announced a new innovative pot - Air-pots - which will be on display at the European Carnivorous Plant Exchange and Exhibition (EEE 2011) (Chester Zoo, 2-3 July). Several other techniques Tim uses to grow carnivorous plants hydroponically will also be on display. One of which will be the Flood and Flow Technique (FFT), which he has recently perfected. Tim says "having had success growing VFTs in a deep water 'bubble' system I've been scratching my head to come up with an easy way to do something similar on a large scale, and one that would suit the needs of several genera. After several sleepless nights thinking of bizarre and complex methods it finally dawned on me that I could simply convert a flood and drain (ebb and flood) system into what I have christened the FFT."

Starting with an EF120 ebb and flood system (ebb and flood) Tim blocked the outlet pipe (drain), which sits next to the inlet pipe, and moved it to the other end of the growing tray. The reservoir was filled with rainwater, from which it is then pumped up into the growing tray using a simple circulation pump to create a 'water table' (the water level is controlled by the height of the drainage outlet). Water topping the drainage outlet drains back into the reservoir. The pump is run 24/7 maintaining the water table and creating a flow of water across the tray. This is a departure from normal use where a segmental timer is used to stop and start the pump allowing the water level to rise and fall to optimise the root oxygen supply in the growing medium. Tim says "a rich root oxygen supply is vital to plant growth so I have added high quality air-stones, three in all, to the reservoir. These run 24/7 creating a frenzy of bubbles which highly oxygenate the water. During the night I may allow the water to drain down to a few centimetres once or twice during the night, for 15 minutes each time, using a timer, to keep things really fresh." To help maintain the oxygen level in the growing season Tim plans to place ice packs into the reservoir on a daily basis. The cool water created will also make growing conditions more favourable to a wider group of carnivorous plants, for example Darlingtonia californica - that's his theory.

Flood and Flow Technique (FFT)

Netted pots are used to contain the medium - a 60:40 ratio of washed expanded clay and live sphagnum moss (LSM) collected from a sustainable source. LSM is used here for three main reasons. Firstly, it's important to keep the water clear to stop the circulation pump clogging up. Secondly, LMS helps regulate an acidic pH. Thirdly, it help's keep the medium above the water level wet but airy. Most of the plants roots hang below the water table, with the rhizome a centimetre or so above. Potting before the growing season is a good idea to allow the moss to grow, to reduce plant stress and to allow the environment to settle. Some protection in winter may be required to prevent freezing, e.g. covering with bubble wrap when frost is expected.

Raising the inlet pipe to the same level as the outlet pipe can avert the risk to the plants from pump failure, but it would reduce water circulation. Once the LSM has established then it should give the grower time to rescue the plants. A tip is to have a couple of pipe sleeves handy to add to the inlet pipe so that the water table can be temporarily maintained if failure happens (or you plan to go away for a few days). Spare sleeves can be purchased from a good hydroponic supplier, e.g. Progrow.

Tim concludes, "the plants I'm growing are Darlingtonia californica, Sarracenia purpurea purpurea, Sarracenia purpurea ssp purpurea heterophylla and Dionaea muscipula. I'm also considering adding the Greater Bladderwort - Utricularia vulgaris to the water that surrounds the netted pots. I'm excited by the potential of the FFT - so fingers crossed. By the time of the EEE 2011 the plants should be well settled in their new home."

A further edition to Tim's collection will be a hydroponic mire for Dionaea muscipula, Drosera species and Utricularia species. The system will be a cross between the drip method and flood and drain.