There are basically five growing methods that I have considered. Of these five, I am more interested in the Nutrient Film Technique and the Flood/Drain System. I am thinking that the flood/drain system would be best suited to growing tomatoe crops since you can grow the plants in gallon containers supported by expanded clay pellets. For lettuce and other short term crops, the NFT system would work well to grow lettuce 4 inches apart using no soil or grow media. The lettuce only needs to be supported by holes inside a gutter cover. Here’s an explanation of the growing techniques.
Nutrient Film Technique: The nutrient is fed into grow tubes where the roots draw it up. The nutrients mixed into water are pumped into a 5” pvc drain pipe, plastic rain gutters, or other types of water-tight trays. In any of these containers, holes can be drilled into the tops about 2 inches in diameter to place net pots in them to direct the roots into the nutrient mixture and contain the plant.
Drip-Irrigation or Micro-Irrigation: The nutrient solution is delivered to the plants through drip emitters on a timed system. (This would be my second choice other than flood/drain. It seems to be a very efficient system for any type of crop).
Aeroponics / Deep Water Culture: The Plant roots are suspended in highly oxygenated nutrient solution. (For some reason, I don’t like this method. You have to provide constant oxygen to the nutrient solution as it is not recycled as in the other systems. I guess my previous experiences with aquariums gave be a bad taste for maintaining oxygenated water).
Flood & Drain: The plant medium and roots are soaked, and then drained at specific intervals. (My choice for Tomatoe crops).
Passive Planters or Self Watering Wicks: A porous growing medium to support plant roots, the plants in the nutrient solution at all times. The plant takes as much or as little water as they want. (I wouldn’t mind experimenting with a small project of this nature, but I didn’t choose this because buying the porous growing medium on a large scale would be too expensive for me.)
Lo Jim…. I am growing 105 tomatos / peppers / melons in 90′ of 6″ black courrogated drainage pipe using the nft method. The pipe is wrapped in a circular manner around an 8′ long x 7′ tall x 3′ wide frame. I use a constant feed 30 gal. rubbermaid container as a resevoir…. I also use 2 tbs. miracle grow watersol vegetable grow every two resevoirs. The plants drink about 4 resivoirs a day. The tomato roots have formed 6″ balls of roots that almost block the flow in the pipe… any ideas on how to keep root balls from plugging up the pipe? Deo
Deo,
It would seem that the roots need more room. You will need to transplant them into their final growing media. This is an interesting learning experience. I will do more research to see if we can find an exact solution to the problem, but here is what I have so far.
Excerpt from: Arizona University (http://ag.arizona.edu)
The three stages of early development are germination, post-emergence, and transplant. Germination should occur within one week of seeding, post-emergence is generally 5 to 12 days, and transplanting should be done between 12 and 14 days from seeding. Once true leaves appear (during post-emergence), seedlings should be transferred into larger growing blocks (pots) from the original seedling cubes, then evenly spaced to maximize light to each plant, without any crowding or shading. The transplants must be spaced so as not to touch one another, and may need to be spread several times during their growth. If crowded, the plants will become spindly. A good transplant is one that is as wide as it is tall. If plants are somewhat “leggy”, with long stems, they can be transferred into the larger blocks with their stems bent 180° , so the original cube is upside-down inside the larger block, and the main stem forms a “U” shape, emerging vertically upward from the block. Tomato plants readily grow adventitious roots from the stems if given the opportunity, producing a stronger plant with more roots. Adventitious roots will grow from the bent stem inside the block.
Transplanting into the final growing media should be done before any flowering. The final growing media should be properly leached and moistened and be at the proper temperatures before plants are brought in. Plants should be irrigated with nutrient solution immediately after moving.
The spacing of tomatoes in hydroponic systems can be much denser than in soil. As little as two square feet per plant (0.2 square meters per plant) have been used with good yields and quality under high light conditions. Spacing is a function of sunlight, so in areas of lower light wider spacing should be applied.
Indeterminate tomatoes must be trained up support strings immediately after transplanting. The strings should be hung from horizontal wires, which are connected to the frame of the greenhouse. These wires will need to support hundreds of pounds of weight, as each mature plant with fruit may weigh 20 to 30 pounds (7 to 14 kilograms). Additional vertical poles can be added to help support the horizontal wires. The wires and strings should be put in place before any other paraphernalia is brought into the greenhouse, and should be at least 10 feet (3 meters) above the ground. The strings should not be re-used, however, a variety of clips are available which can be sterilized and re-used. As the plants grow, the strings are unwound from their hangers and moved along the horizontal wire, effectively “lowering” the plants without breaking them. Mature indeterminate tomato plants may be 40 feet (12 meters) in length, and can grow much more.