If you’ve ever grown a backyard tomato, or kept a coleus alive through the winter, you have all the expertise you need to grow plants hydroponically. Quite simply, hydroponics is the method of cultivating plants without using soil. The plants are grown in a non-nutritive medium, such as gravel or sand, or in lightweight, man-made materials such as perlite, vermiculite (a mineral-mica nutrient base), or Styrofoam. Nutrients are then supplied to the plants in one of two ways: either by soluble fertilizers that are dissolved in water, or by time-release fertilizers that are mixed into the medium.
The advantages of a hydroponics system over conventional horticultural methods are numerous and varied. Dry spots and root drowning do not occur. Nutrient and pH problems are largely eliminated, since the grower maintains a tight control over their concentration. There is little chance of “lockup,” which occurs when nutrients are fixed in the soil and unavailable to the plant. Plants can be grown more conveniently in smaller containers. And, because there is no messing about with soil, the whole operation is easier, cleaner, and much less bothersome than it would be with conventional growing techniques.
Most hydroponic systems fall into one of two broad categories: passive and active. Passive systems, such as reservoir or wick setups, depend on the molecular action inherent in the wick or in the medium to make water available to the plant. Active systems, which include the flood, recirculating drip, and aerated water systems, use a pump to send nourishment to the plant.
Most commercially made “hobby” hydroponic systems designed for general use are built shallow and wide, so that an intensive garden with a variety of plants can be grown. However, most marijuana growers prefer to grow each plant in an individual container. Indoors, a three-gallon container is adequate. Outdoors, a five-gallon (or larger) container should be used if the water cannot be replenished frequently. Automatic systems irrigated on a regular schedule can use smaller containers, but all containers should be deep, rather than shallow, so that the roots can firmly anchor the plant.
Written, Maintained and posted occasionally to rec.gardens and alt.hemp by Jeff Burchell