Bending and Pruning...to maximize light

In some growing situations it is more advantageous to have plants that are wider than taller in order to maximize the number of branches or "leaders" within a given area. It is less efficient in most indoor applications to have one large branch than it is to have several smaller ones. This is true due to the fact that when dealing with distance in terms of height, you must consider that artificial light intensity typically drops 50% for every foot it travels away from the initial source. So if a 5' tall plant has a 1000Watt HPS producing 140,000 initial lumens is suspended 18" (1.5 ft ) above, theoretically, the most light the lower branches may receive would be around 2187 lumens, only 1.5% of the amount of light available in the first foot away from the light source. For example:

1st foot: 140,000lumens X 0.5= 70,000 lumens
2nd foot: 70,000lumens X 0.5=35,000 lumens
3rd foot: 35,000 lumens X 0.5=17,500 lumens
4th foot: 17,500 lumens X 0.5=8,750 lumens
5th foot: 8,750 lumens X 0.5=4,375 lumens
6th foot: 4,375 lumens X 0.5=2187.5 lumens

Shorter plants will receive more even lighting from top to bottom, and as a result will ripen more evenly, have a higher percentage of A+ flowers, have a lower percentage of "trash" to be cleaned off the finished product, and yields become very consistent from plant to plant. Once the technique is mastered, it will simply be a matter of counting stems to determine yields. One of the most common methods used is to take advantage of these principles is the "sea of green method". There has been a lot of good writing on this method, and it has proved to be very effective for many growers who are willing to endure a couple of experimental crops while they are learning the technique. Once dialed in, growers usually have to pick up their jaw at harvest time. One of the disadvantages to the sea of green method is that it requires a large, constant supply of fresh plants. Where the grower may have had one plant in the past, they now have nine.

There is a specialized method of keeping plants very short, while producing many upright branches without the use of chemical growth regulators. So now instead of having 9 plants in a 2' square you can have one plant that will have as many upright branches of the same height than with a conventional sea of green method. The plants are wider than tall, and allow maximum light intensity to penetrate the dense canopy to reach each individual flower. The finished plant should have the appearance and glow of a chandelier by harvest time.

The best candidates for this technique are plants that like to branch a little more, plants that tend to branch less are still very suitable but may require a little more time in vegetative growth before they can be flowered. One of the keys to this technique is the timing of when cuttings are removed from the mother plant. Typically, growers remove clones from mother plants that are maintained in the vegetative growth phase. For success with this technique it is best if cuttings are taken in the 2nd or 3rd week of flowering. For growers who have never tried to root a cutting from a flowering plant, relax: they will root and you will be pleasantly surprised at the results. Some growers may not even recognize their plants during phases of this technique. There are several advantages to taking the cuttings from flowering plants. One benefit is that the grower can devote less space to mother plants, and can take cuttings from the crop in progress provided that it is healthy and vigorous, has not been over-treated with growth regulators, and appears to be free of disease and pests. Also, the cuttings taken from early flowering plants will take longer to root, usually 2 weeks or so for the rooting phase. Rooting pre-flowering cuttings requires 24hrs of light. This works out very well, as timing is very important to achieve success with this technique. If your plants require an 8 week flowering period, and cuttings are taken two weeks into flowering it leaves 4 weeks for vegetative growth after accounting for the 2 week rooting period. This is the perfect amount of time to develop short, highly branched plants ready to re-fill the grow room after harvest.

The main reason that cuttings are taken early into flowering is that many flowering short-day annuals will develop more internodes per inch of shoot growth in early flowering than in vegetative growth phase, where internodes tend to be spaced further apart. This will translate into many branches extending from a central point after returning to vegetative growth on a plant that has increased very little in height. In order to ensure profuse branching, one week after rooting (allowing some time for the plant to develop some new shoot growth), the apical meristem or central growing point is either bent back and tied with copper wire (ground wire from old discarded residential wiring works great) or simply removed. The bending method is preferred as it may allow for hormones within the growing tip to be diffused and translocated to other growing points, as opposed to being removed all together. The result will be an extremely short plant with many, many branches. Internodal growth tends to be tighter as the plant is still partially flowering while growing. Also, the plant will have maintained some of it's flowering hormones and will respond very quickly when returned to flowering. Once or twice during the four weeks of new growth after rooting, lightly mist your plants with high quality fulvic acid mixed with a liquid sea kelp product as per the manufacturer's directions. The natural cytokinins will encourage branching and rapid cell division.

As for nutrients, start by pre-soaking the rooting medium in 1/4 strength (about 350ppm) full spectrum hydroponic bloom formulation (higher in phosphorous and potassium). Additions of high quality fulvic acid will also encourage healthy roots and vigorous new plants. After the cuttings have rooted, use a half grow to half bloom solution at around 500 ppm. One to one and a half weeks later, switch to a 3/4 to 1/4 ratio of grow to bloom solution and gradually increase the nutrient concentration to 1000 ppm. Make sure that the fertilizer you are using is complete and contains all the necessary elements required for plant growth (N, P, K, Ca, S, Mg, Fe, Zn, Mn, B, Mo, Cu and possibly Co and Ni) Your plants may not look as they usually do in this stage of growth, not to worry though, likely you have been surprised by the increased rate of branching. You may need to bend and prune some of the branches off in order to maximize light entering the plant canopy. For the last week of vegetative growth, use a full strength growth formulation. For feeding plants in a soil/soilless mix, follow the strength(s) recommended above every 1/3rd watering or use at 1/4 strength each watering. Allow 10 to 15% of nutrient to run-off with each irrigation to help to reduce salt build up in the root zone (rhizosphere). Follow your usual regimen for feeding in the bloom phase. A light spray of cytokinin containing products such as sea kelp with high quality fulvic acid once a week for the first three weeks of flowering will increase the number of flowering sites produced on each plant, and provide a full range of naturally occurring and trace elements. You may not want to spray kelp products on your plants while adding flowering enhancers to your nutrient solution.

If the final space allocated to each plant is to be a square foot, prune and bend the plant so that there are about 9 branches equal in height per plant per square foot of growing area. After two to three weeks into flowering, the lower 1/3 portion of the plant can be trimmed to supply cuttings for the next crop and improve air circulation in the plant canopy.

As a word of caution, if a plant is re-cut and re rooted many times, the window of opportunity for viruses and other growing problems increases. Occasionally, it is a good idea to start fresh mother plants from seed to ensure healthy crops, although you may consider otherwise if your crop continues to perform.

Hopefully, you will enjoy continued success with this technique, which stems from ancient bonsai pruning practices. Although thousand of years old, these practices can help even the most cutting edge grower realize improved results. It's an interesting thought to note that many of the modern practices developed today might be followed by other growers centuries from now. We may not live forever, but what we leave behind can.

Here are some additional tips for producing low profile, densely branched plants:

• Target your oscillating fans to vigorously sweep the upper portion of the plant canopy
• Enhanced HPS or metal halide bulbs produce more light in the blue portion of the spectrum. This often results in tighter internodal spacing in many plant varieties.
• Plants will stretch more in high humidity. Wire a de-humidifier or small exhaust fan to a de-humidistat to keep humidity below 60%
• Day / Night temperatures can tighten internodal spacing. Shorter, bushier plants can be influenced by maintaining the day time temperature less or equal to night time temperature
• High light, low heat produces very healthy plants. Air cooled shades can help to control heat, while increasing lamp to plant tolerances