Marijuana Horticulture: The Indoor/Outdoor Medical Grower's Bible

mix heavy in coco peat to wick up the nutrient solution. Such low-tech gardens are very productive.
    Dutch growers line the floor of a room with heavy plastic or pond liner. They fill three-gallon (3 L) pots with an absorbent soilless mix that holds plenty of air. They flood the garden with two to three inches (6-9 cm) of nutrient solution. Roots absorb the nutrient solution in two to five days. No nutrient solution is drained off; it is all absorbed by plants!
    One Spanish grower uses passive irrigation to water his garden. He drives a delivery truck and is away from home five days a week. He keeps his indoor garden under a 400-watt HPS lamp. The plants are in a rich potting soil, and the pots are in a large tray with four-inch (12 cm) sides. Every Monday morning he fills the tray with mild nutrient solution. When he returns on Friday, the plants are strong and happy!
    Active hydroponic systems “actively” move the nutrient solution. Examples of active systems are: flood and drain, and top feed. Cannabis is a fast-growing plant and very well suited to active hydroponic systems.
    Active hydroponic gardens are considered a “recovery” system if the nutrient solution is recovered and reused after irrigation. A “non-recovery” system applies the nutrient solution once, then it runs to waste. The solution is not reused. Non-recovery systems have few complications but are not practical for most cannabis hydroponic gardens. The commercial growers “run-to-waste” systems are avoided, because they pollute ground water with high levels of nitrates, phosphates, and other elements. Indoor growers seldom use non-recovery systems, because they require disposing of so much nutrient solution into the local sewer system.
    Active recovery hydroponic systems such as the flood and drain (ebb and flow), top feed, and nutrient film technique (NFT) are the most popular and productive available today. All three systems cycle reused nutrient solution into contact with roots. Recovering and reusing the nutrient solutionmakes management more complex, but with the proper nutrient solution, schedule, and a little experience, it is easy to manage. Active recovery systems use growing mediums that drain rapidly and hold plenty of air, including: expanded clay, pea gravel, pumice rock, crushed brick, rockwool, and coconut coir.
Ebb and Flow Gardens
    Ebb and flow (flood and drain) hydroponic systems are popular because they have proven track records as low maintenance, easy-to-use gardens. Ebb and flow systems are versatile, simple by design, and very efficient. Individual plants in pots or rockwool cubes are set on a special table. The table is a growing bed that can hold one to four inches (3-10 cm) of nutrient solution. Nutrient solution is pumped into the table or growing bed. The rockwool blocks or containers are flooded from the bottom, which pushes the oxygen-poor air out. Once the nutrient solution reaches a set level, an overflow pipe drains the excess to the reservoir. When the pump is turned off and the growing medium drains, it draws new oxygen-rich air into contact with the roots. A maze of drainage gullies in the bottom of the table directs runoff solution back to the catchment tank or reservoir. This cycle is repeated several times a day. Ebb and flow systems are ideal for growing many short plants in a Sea of Green garden.

Nutrient solution floods the growing bed and drains back into a reservoir in an ebb and flow garden.

Nutrient solution is pumped up into the bed via the short flood fixture on the left. The overflow fitting on the right guarantees the nutrient solution will not spill over the top of the table.

Self-leveling legs, similar to those of a washing machine, support this ebb and flow garden bed and ensure all plants receive a level dose of nutrient solution and that it all drains back into the reservoir below.

Nutrient solution can be applied from above and the table serves as a drain.

The grow room is lined with white Visqueen. The grower takes off his shoes to avoid damaging the plastic and to keep the grow show clean.
    Flood the table to half to three-quarters the height of the container to ensure even nutrient solution distribution. Avoid lightweight mediums such as perlite that may cause containers to float and fall over.
    A large volume of water is necessary to fill the entire table. Make sure the reservoir has enough solution to flood the reservoir and still retain a minimum of 25 percent extra to