The Concept of NFT is simple. The plant roots grow on a surface that has no more than 1 mm of nutrient moving slowly across it. This is called Nutrient Film Technique, as the nutrients are a film on the base of a flat surface (like a damp surface). The plants roots are not submerged, and have access to the air, yet can draw up as much nutrient as they require from the damp surface. We usually use channels for this as channels or gullies keep the light out of the root zone. Light on the roots generally slows the growth rate. By having a running Solution of 750 ml to 1 litre per minute down a flat surface at 1:40 slope (1:40 = 25 mm drop every meter) we can achieve the nutrient film.

Dr. Allan Cooper in England invented this technique, during the 1970’s to save the British Glasshouse industry from cheaper European imported vegetables. It had to be inexpensive to produce crops, and inexpensive to set-up. Therefore, the nutrient should be the only cost for running (except minimal pump power), and there should be minimal need for cleaning and other labour. NFT has proven to be one of the top performance systems, as well as being the lowest maintenance system in terms of cost.

The Plant is grown in a media that is has low water-holding capacity, and large particles, so air can move around the roots. The Plant is fed by pumping the nutrient through dripper lines. By altering the amount that is feeding the plants or by using a timer, the oxygen to nutrient ratio can be adjusted. The ideal situation is to keep the roots reasonably moist, but not wet. Results are also good if excess nutrient is used to feed the plants roots, followed by a break for them to drain off a little. The plant roots are never immersed in nutrient at any time.

Drip Systems give the greatest latitude to the designer. Almost any container can work as long as it is a food grade Plastic, Fibreglass, Polystyrene, Stainless Steel or other non-phytotoxic container. All you have to achieve is moisture at the plant roots, and have the container drain well to provide good oxygen levels around the roots. As the plant grows, the amount of nutrient required may increase slightly as the plants consumption rate goes up, but oxygen levels must never be compromised.

Drip either onto the surface of the media or just below if you wish to avoid algae on the top of your media. Ordinary garden type drip irrigation fittings seem to work very well. Ensure that drain fittings do in fact drain, and will not get clogged up by media or roots. Any nutrient pooling in the bottom of the container due to incomplete drainage can lead to root problems, as this nutrient can become stagnant, and rot the roots that grow into it. Do not use brass or other metal fittings in your design.

Flood and Drain uses two cycles to feed oxygen and Nutrients to the roots. These are the Flood Cycle, and the Drain Cycle.

FLOOD CYCLE: To get high oxygen into the root zone, we can flood the root zone with nutrients, and expel all “dead air” from around the roots.
DRAIN CYCLE: After the Flood Cycle (2 to 15 mins) we can drain the nutrients quickly to draw or “suck” fresh oxygen into the root zone as the nutrients drain out and at the same time, leave the roots damp with nutrient. (15 to 45 mins) Sound Complicated? It’s as easy as Pump on and Pump off !

The process of growing plants in an air/mist environment without the use of soil or an aggregate media. Aeroponics is all about air --and lots of it-- especially when air is combined with micro-droplets of water. Add a few trace minerals and macro-nutrients to the water, and almost any plant can grow to maturity in air.

The hydroponic method of plant production by means of suspending the plant roots in a solution of nutrient rich, oxygenated water. Traditional methods favour the use of plastic buckets with the plant contained in a net pot suspended from the centre of the lid and the roots suspended in the nutrient solution.

Hydroponic systems can be either active or passive. An active system includes a mechanical means for recirculating the nutrient solution while a passive system relies on capillary action/absorption and/or the force of gravity to replenish roots with nutrient. Besides being generally more efficient, and thus more productive, a nice feature of active systems is the ease at which they may be implemented within an automated greenhouse.

A technique of growing lettuce and other short crops that require no vertical support is the raft system. In this method, plants are supported in baskets that fit into styrofoam sheets and float upon a bath of nutrient solution. The nutrient solution is circulated and aerated from below to maintain a high level of oxygenation and avoid stagnation. The raft system is a very economic means of producing large quantities of lettuce and mixed greens in a short amount of time.