What Are Low Stress Training Methods?
Low-stress training methods elicit similar effects to high-stress training (HST) like increased yields and more productive bud sites. However, low-stress training does not risk causing as much damage as high-stress training methods. Low-stress training cultivation methods may be seemingly mundane but are actually taking advantage of highly complex chemical signaling mechanisms inside the plant. If performed properly, no greater harm comes to the plant.
Low-stress training (LST) may be used indoors or outdoors. These techniques alter chemical balances in plants and result in changes to the way plant look and how they grow. LST does not cause damage to the plant, where HST does involve breaking or cutting the plant. Both techniques aim to prevent the plant from growing in its natural state which produces one large main bud on the top of the plant (the cola), minimizing floral yield. The hormone auxin causes plants to grow in height and levels of auxin are highest in the top-most parts of the plant. Reducing this hormone concentration produces a larger canopy with fewer large singular colas.
Low-Stress Training Methods: Tying
The main stalks of the plant may be bent in an “L” shape to force more auxin to be distributed to the rest of the plant. The top of the plant may be continually tied down as the plant grows. Plant tape is best to use to prevent damage. The end result is a plant with stalks that lie around the plant’s pot and have several exposed budding sites. In the floral growth stage colas of flowers will grow upwards towards the light. Screen of Green is a modified form of this method where branching growth is woven and tied into a screen.
Low-Stress Training Methods: Screen of Green
Screen of Green (SCROG) is a method of low-stress training that optimizes light use by forcing lower plant parts to grow to the top of the canopy to allow for more floral production and a bushy plant shape. It can be used effectively with high intensity or fluorescent lighting and optimizes yield when space is limited.
The SCROG method involves tying plants to a suspended screen above the canopy as they protrude to train the plant to grow a level floral and leaf layer with stems and branches below the screen. The tops of the plants are trimmed off to encourage plants to grow outward instead of upward. It has been estimated that the SCROG method can increase yields by up to 20%.
Screen of Green
- Rooted seedlings or cuttings (about 1-month-old) are transplanted into a 5-7 gallon pot or bucket filled with soil medium. Seedlings should be watered with ~8.5 oz pH 6.0 water near the stem of the plant.
- 2x2 inch Screen is cut to fit the tent or grow room and set ~15 inches above the plants. The screen should not be tied up too tightly and it should allow for movement. Cable ties are recommended of suspending the screen from dowels or tent poles. 20-25 inches more space is needed above the screen for the grow lamp.
- When the plant grows to ~10 inches height, top cluster of buds may be pruned. When the top of the plant reaches the screen bottom branches may be pruned, this practice is termed “tucking.” Clean and sharp scissors should be used to prevent damage or infection to the plant. Plants should be kept in vegetative growth until the mesh screen has been filled below the screen without gaps. Any branches that begin to protrude earlier may be gently bent back under the screen.
- Two days after pruning, usually 6-8 weeks into growth, flowering may be induced. If a hydroponic system is being used, growth times may be shorter. Switching the light exposure time from 18-24 hours to 12 hours of light and 12 hours of dark will induce flowering. When the branches have grown 4 in through the screen they may be tied to the screen with wire or rope. New growth may be pruned or tied as needed to maintain a level canopy, any branches that do not grow through the screen should be pruned so as not to waste plant resources on buds that will not mature into usable floral material.
How Much More Money Can You Make Using Screen of Green?
The Screen of Green method was tested in a 2010 study aimed at determining the yield and income of illegal growers for the purpose of aiding prosecution. The cultivation method was selected to replicate typical illegal indoor hydroponic growing operations. Though the purposes and scale of the study are not quite the same as looking at a greenhouse business, the difference in crop productivity is notable!
- The most successful cycle yielded an average of 881g (31.1oz) of dry, groomed female flowering head per plant
- Over the whole study, the 18 plants yielded an average of 687g (24.2oz) of dry head per plant
Value of Plants Harvested in Study
|Treatment Group||Sold as Pounds ($3500-5000)||Sold as Ounces ($250-500)||Sold as 0.5-1 Grams ($20)|
|Grow 3 (no ScrOG)||$20,615-29,450||$23,555–47,110||$53,420-106,840|