Testing The Varieties: Part 6


Last month, the winter garden was still hanging, taking a long time between drying and curing. Now they are all properly dried and are hanging out in glass jars. The buds were tested using infrared light to determine percentages of cannabinoids. We tested for heated THC and heated CBD for a number of different strains.

Photo 1The THC levels (link the levels to http://www.edrosenthal.com/#!blog/rxf1s)  were not high. The main reason is that the plants were receiving only a moderate amount of light during flowering. The total hours of light averaged only about 10.5 hours daily. The winter and early spring sunlight received was weak and mostly indirect. This was supplemented with six hours of HPS light, still too little to produce maximum bud development and to reach THC potential.

THC levels differed greatly between strains, showing the relative THC/CBD potentials of the varieties. Except for specialty varieties, all had very little CBD. Varieties differ in effects because they have different ratios of terpenes (odor molecules that affect mood and have medical qualities).

About eight weeks ago, I picked up five plants, transplanted them and then let them grow in the Photo 2greenhouse. They were under lights for an extended period each day, long enough to prevent them from flowering.

About four weeks ago, the supplemental lighting was turned off and the plants started to flower. A couple weeks later, the plants were showing the slightest sign of temptation to turn vegetative, some leaf growth and a slight stretching of bud. I had to take action immediately to prevent the plants from returning to a vegetative state. The solution was to increase their dark time to 12 hours or more each day.

I decided to use a 5’ x 9’ “utility frame” built for a previous project and covered it using a high grade reinforced opaque polyethylene film. “Panda plastic” is colored white on one side and black on the other. The frame was wrapped white side out, reflecting sunlight to keep the interior cool. The black interior absorbs any stray light that enters. No light entered when the flaps were closed.

Photo 3Each of the five plants were in five gallon soft containers, sitting in 4’ x 8’ trays and placed on top of a moving caster, for easy mobility. Each evening towards the end of dusk, the plants are pushed into the dark chamber. Yesterday, that occurred at 9pm. In the morning, bright and early at 11am, the flaps are opened and the plants are wheeled into sunlight. They receive about 11 hours of light and 13 hours of darkness daily. The long dark time promotes flower ripening.

The first of the five plants, a Rom-Grapefruit, is almost ripe. In the last two weeks, it transformed from a softy to a hard ripe bud bulging with trichomes. The other four plants will ripen within the next week or two.

The dark chamber is a convenient addition to my tool chest of growing supplies and I intend to use it again for my next crop.


  • The dark chamber is used to prolong the dark period, promoting flowering.
  • The flaps are up and the plants are about to emerge.
  • The tray is resting on a moving caster, making it easy to push around the yard during the day allowing the plants catch the best rays as well as avoid shade.
  • The plants are basking in the sun.
  • Ripening bud of Rom-grapefruit will be picked next week.


When you are growing plants in containers with wheels, it’s easy to move them around. Even large plants can be moved without too much effort.  This can become an important factor as the position of the sun changes over the season. Parts of the garden that were in sun early in the day or earlier in the season often become shaded later on. Moveable plants can always be in a sunny position.

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