Growing Medium Problems

Marijuana Horticulture

by Jorge Cervantes

These maladies are caused by growing medium problems but manifest as nutrient problems. The solution is found within the growing medium.

When water is abundant in the growing medium, roots easily absorb it. Roots use more energy to absorb more water as it becomes scarce. Finally, the point comes when the substrate retains more moisture than it surrenders, and the roots receive no water. A good growing medium readily yields its bank of stored water and nutrients to a plant’s roots. The more easily cannabis absorbs nutrients, the higher the yield.

The cation-exchange-capacity (CEC) of a growing medium is its capacity to hold cations that are available for uptake by the rots. The CEC is the number f cation charges held in 3.5 ounces (100gm) or 100 cc of soil and is measured in milli-Equivalents (mEq) or Centi-Moles/kg on a scale from 0-100. CEC of 0 means the substrate holds no available cations for roots. CEC of 100 means the medium always holds cations available for root uptake. Growing mediums that carry a negative electrical charge are the best.