How much light is too much?

Is a 24 hour vegetative photoperiod too long?

I just read an article of yours in which you advocate a 24-hour photoperiod during vegetative growth. I disagree.
I read that the main reason tropical marijuana is more powerful than northern strains is because of the difference in the time required to trigger flowering, as well as the difference in the photoperiod. The article was accompanied with graphs relating THC content to the difference in the maximum summer light available and the minimum flowering period. It clearly indicated that plants that grow closest to the equator have the highest concentrations of THC. Close to the equator, the longest "summer" days are approximately 13 hours, while the minimum "winter" sunlight was still 11 hours. Plants from these areas contained far greater concentrations of THC than the high latitude varieties, where the summers are 15-18 hours and the winters only six to nine hours, depending on latitude.

Northern outdoor grown pot is big and looks good, but it doesn't come close to equatorials like Jamaican tropical Lamb's Bread in its stoniness. Commercial sinsemilla is also inferior. It also looks great and smells delicious, but it just doesn't have the kick! The long days of the high latitude summers are detrimental to THC production.

Connoisseurs should give the plants no more than what keeps them from flowering 14 hours of light and cut it back to 11 hours during flowering for the best kick-ass sinse this side of Jamaica.

The Doobiedoobiedoo Kid,
Internet

You probably read information based on researcher's studies that the THC?CBD ratio of adapted varieties changes with changes in latitude. At the equator, the plants contain mostly THC, the psychoactive cannabinoid. As the latitude gets higher, the ratio of CBD rises in comparison to THC. At the 30th parallel, plants from adapted varieties produce about equal amounts of CBD, a non-psychoactive cannabinoid that potentiates THC, and THC. The 30th latitude bisects the Hindu Kush valley, home to Afghani and Indica varieties.

The adaptation of cannabinoid ratios to latitude evolved over hundreds or thousands of generations with occasional intercession by humans. The plants with cannabinoids closest to the favored ratio for a particular latitude performed better and produced more seeds and offspring. Eventually these plants became predominant in the area.

These plants' cannabinoid ratios are genetically determined. No matter where they are grown ? in their home territory, at the equator or in higher latitude climates ? high THC plants will produce high THC and not CBD. Conversely, high CBD plants grown at the equator will remain high in CBD.

When given different conditions, clones of the same plant vary slightly in their cannabinoid compositions and their potency. Factors that affect cannabinoid production include soil and nutrients, light intensity and the amount of UV-B light. Equatorial and high altitude areas receive more UV-B light than low altitude, high latitude areas. However, a White Widow won't change stripes. Growing a Chardonnay in a different area may change the taste of the grapes slightly, but the wine will remain a Chardonnay and not become a Burgundy.

I don't see how the light cycle during the vegetative stage would affect the plants when they are flowering. The long light cycle just gets the plants to the size for forcing flowering more quickly. Trying to grow many of the commercial varieties under 14 hours of light, 10 hours of darkness during the vegetative cycle would result in the plants being triggered to flower. Even with a continuous lighting regimen for vegetative growth, once the plants are in flowering under electric lighting, they receive almost the same light cycle that they would at the equator, 12 hours with light and 12 hours without light.

To get the intense equatorial highs growing outdoors in a high latitude area, I would start equatorial Sativas under lights with a 12-on/12-off photoperiod. As soon as it is warm enough, the plants should be placed outdoors. However, they should be kept on the 12-12 regimen, or even placed on 13 hours a day of uninterrupted darkness. To force the plants under this regimen, build a frame so that shadecloth or white/black polyethylene can be placed over the plants each evening and removed each morning. This way, the equatorial plants, which flower for up to 180 days, can complete their flowering during the summer, when the light intensity and UV-B light are at their peak.

Your attitude about modern marijuana is unfounded. Breeding programs all over the world have resulted in new varieties that tend to be potent, prodigious and faster growing than in the past. While you might wax romantic about the marijuana available thirty years ago, more of the current offerings are complex and high quality.

Readers with grow questions (or answers) should send them to Ed at: Ask Ed, PMB 147, 530 Divisadero St, San Francisco, CA 94117, USA.
You can also email Ed at AskEd@cannabisculture.com and send queries via his website at www.ask-ed.net.
All featured questions will be rewarded with a copy of Ed's book, The Big Book of Buds. Sorry, Ed cannot send personal replies to your questions.

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