Yep both me hinks
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Thank you Light Addict! Is sex determined environmentally or genetically, both? I've always wondered how that works with cannabis plants.
This is actually an interesting topic.
Genetically - MJ is pre-programmed to come out 60% female.
The actual sex is not determined until the fourth or fifth week of veg. Depending on environment - I believe you can go as high as 90% males. There was a study done by Dutch Seeds - it is still available on the web - which included this result:
Of the 5 above-mentioned environmental factors the first three are the most practical:
Level of nitrogen and potassium of the seedbed: A heightening of the standard level of nitrogen makes for more female cannabis plants originating from the weed seeds. A lowering of the nitrogen level shows more male cannabis plants. A heightening of the level of potassium tends to show more male marijuana plants, while a lowering of the potassium level shows more female marijuana plants. A combination of a higher nitrogen level for the period of a week or two and a lowering of the potassium level is recommended.
Did not attempt to control N, P, or K specifically for this grow. I just used a modified FF Nutrient Schedule. Thanks to all the information I gathered on this site I avoided over-ferting.
Humidity and moistness of the seedbed: a higher humidity makes for an increase in the number of female cannabis plants from weed seed, a lowering for an increase in male cannabis plants. The same is valid for the moistness of the seedbed.
Humidity was typically 40-60% and was stable whenever the house evaporative cooler was running. This will probably prove more difficult to maintain during heating season without some sort of humidification. The seedbed, once I got the watering schedule under control, was relatively moist. Interestingly enough the male plant came from one of the waterlogged pots.
Level of temperatures: lower temperatures make for a larger number of female marijuana plants, higher temperatures for more male marijuana plants.
I guess I dodged that bullet since my temps were regularly topping out in the mid 80's. Nightime temps bottomed out in the low 70's. In fact. I'm dealing with high temperatures right now in flowering due to the increase light wattage and lower CFM of extraction system, 130 CFM (w/Carbon Filter) compared to 191 CFM from 6" clip fan. I'm hoping that since they vegetated in a high temp environment, that the high temps during flowering won't induce any shock or hermaphrodism.
Colour of light: more blue light makes for female cannabis plants from seed, more red light makes for more male cannabis plants.
I used all blue light (6400K/5000K) throughtout vegetation.
Hours of daylight: few hours of daylight (e.g. 14 hours) makes for more female individuals, a long day (e.g. 18 hours) makes for more male cannabis plants.
Sounds like in my case, GLR might be the biggest contributor to my female ratio. Good news since I plan to adopt GLR for all of my future grows.
I do not plan on topping them for a couple reasons.