The following is a reprint from Pod Racer (major props for all his forums/journals have done to enlighten me) long before 'Feminized" seeds were being promoted. It provides numerous tips to tilting the amount of females (or males) you wind up with ...
1. Level of nitrogen and potassium of the seedbed: A heightening of the standard level of nitrogen makes for more female plants originating from the seeds. A lowering of the nitrogen level shows more male plants. A heightening of the level of potassium tends to show more male plants, while a lowering of the potassium level shows more female 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
2. Humidity and moistness of the seedbed: a higher humidity makes for an increase in the number of female plants from seed, a lowering for an increase in male plants. The same is valid for the moistness of the seedbed.
3. Temperature: lower temperatures make for a larger number of female plants, higher temperatures for more male plants.
4. Light Spectrum: more blue light makes for female plants from seed, more red light makes for more male plants.
5. 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 plants.
Now let me just make a few adjustments here to this. You can do whatever you want to your plants in seedling stage and early vegetative stage of growth and it will not effect your final male to female ratios.
6. Critical Time: The time when things should be near perfect is in or around the 3rd to 4th week of vegetative growth. This is the CRITICAL TIME for getting those female ratios up and up. I realized this clearly when noticing how some plants hermed because of problems that occurred around this period of the plants development. If the problems occurred before this time - no herms. So for this reason I surmised that this is when the crucial gender selection is made by the plant. Now I believe that the genders are set in the seed however the environment has a massive impact on how this is expressed in the final phenotypic expression of the plants gender. There are probably many genes that govern this, however lets get into how to up these female ratios.
At the 3rd to 4th week of vegetative growth make sure that your plants are free from stress. No pests attacks, no fungi attacks, no mold, no irregular photoperiod, not underwatered, not overwatered, not pruned or topped, a cannabis friendly soil mix, not recently transplanted, no small pots. If have these basic growing conditions under control then we can move onto the real forces of female production from standard seeds.
7. Nutrients: N
:K and nutrients. What this simply boils down to is that you have the right nutrients present in the right ratios. A nutrient formulation that has roughly equal parts N, P and K is great but if the P levels go up or the N levels go down you are starting to look at a flowering type food for cannabis. If you do this then your odds of producing mostly females is greatly decreased.
Make sure that you get those N, P and K levels to almost run from higher to lower amounts from N to P to K. I have noticed that equal portions of N to P an K can help with the female ratios but the higher N is certainly more helpful. So around the 3rd of 4th week of growth make sure that the ratios are good and that P or K has not gone above the N and P or else more males will occur. Obviously this means to avoid overfeeding your plants around this time too.
Never let your medium dry out completely around the 3rd to 4th week of vegetative growth. If you make sure to water occasionally, but not to over water your plants, you will get those female ratios on the up and up.
Both over watering or drying out of the medium will produce more males. For consistent results in getting more females keeps those mediums moist.
8. Humidity: Now this is the tricky one. High humidity levels only promote fungi and mold development and lowering humidity levels is the way to cure most of this rot but by keeping those humidity levels up in or around the 70 RH factor will help to produce more females.
If you have a low humidity grow room then you should get to hold of a humidifier. Now high humidity levels like 70 RH cause the medium to dry out a lot quicker so you have to keep this under control too. Keep those mediums moist and those RH levels at 70. This will help to improve those female to male ratios. Again, getting them on the up and up.
If you run the 24/0 photo period then do not allow those temps to go anywhere above 85 unless you have an equatorial strain. 75 is the best but going a little lower is not a problem for helping those female ratios. If you can get in at around 65 then those females are going to be popping up all over the place. The problem with this is that some growers like to use the 18/6 photo period and when the lights are off the temps drop from around 65 to 50 and even less. Try not to be below 55 because this has the adverse effect on the plants producing more males than females. Again between 65 and 75 is where you want to be during the 3rd to 4th week of vegetative growth, the preference being 70.
The following is pre LED
Invest in a MH Light for vegetative growth. Dump the HPS bulb for flowering later. I have noticed that HPS lighting during vegetative growth simply sends those males to female ratios all over the place. With MH lamps the females are everywhere. Invest in some MH HID lights. It makes all the difference in getting those females to show more often. This is worth repeating! MH Bulbs produce more females under optimal conditions especially if they are present during the 3rd and 4th week of vegetative growth. Surprising enough you can start seedlings under HPS and it will not have an effect on those female ratios. Again the 3rd to 4th week of vegetative growth is what is important here.
No stress during the 3rd to 4th week of vegetative growth. That is all there is to it. If you got your garden growing in optimal conditions without plant stress then the impressive 90% to 95% females start to emerge from standard seed packs.
I find that topping is best done at the second to third week of vegetative growth but that this is a little stressful and can lead to those female ratios dropping again. Avoid topping or pruning if you are looking to up the female count.
1. Level of nitrogen and potassium of the seedbed: A heightening of the standard level of nitrogen makes for more female plants originating from the seeds. A lowering of the nitrogen level shows more male plants. A heightening of the level of potassium tends to show more male plants, while a lowering of the potassium level shows more female 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
2. Humidity and moistness of the seedbed: a higher humidity makes for an increase in the number of female plants from seed, a lowering for an increase in male plants. The same is valid for the moistness of the seedbed.
3. Temperature: lower temperatures make for a larger number of female plants, higher temperatures for more male plants.
4. Light Spectrum: more blue light makes for female plants from seed, more red light makes for more male plants.
5. 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 plants.
Now let me just make a few adjustments here to this. You can do whatever you want to your plants in seedling stage and early vegetative stage of growth and it will not effect your final male to female ratios.
6. Critical Time: The time when things should be near perfect is in or around the 3rd to 4th week of vegetative growth. This is the CRITICAL TIME for getting those female ratios up and up. I realized this clearly when noticing how some plants hermed because of problems that occurred around this period of the plants development. If the problems occurred before this time - no herms. So for this reason I surmised that this is when the crucial gender selection is made by the plant. Now I believe that the genders are set in the seed however the environment has a massive impact on how this is expressed in the final phenotypic expression of the plants gender. There are probably many genes that govern this, however lets get into how to up these female ratios.
At the 3rd to 4th week of vegetative growth make sure that your plants are free from stress. No pests attacks, no fungi attacks, no mold, no irregular photoperiod, not underwatered, not overwatered, not pruned or topped, a cannabis friendly soil mix, not recently transplanted, no small pots. If have these basic growing conditions under control then we can move onto the real forces of female production from standard seeds.
7. Nutrients: N
:K and nutrients. What this simply boils down to is that you have the right nutrients present in the right ratios. A nutrient formulation that has roughly equal parts N, P and K is great but if the P levels go up or the N levels go down you are starting to look at a flowering type food for cannabis. If you do this then your odds of producing mostly females is greatly decreased. Make sure that you get those N, P and K levels to almost run from higher to lower amounts from N to P to K. I have noticed that equal portions of N to P an K can help with the female ratios but the higher N is certainly more helpful. So around the 3rd of 4th week of growth make sure that the ratios are good and that P or K has not gone above the N and P or else more males will occur. Obviously this means to avoid overfeeding your plants around this time too.
Never let your medium dry out completely around the 3rd to 4th week of vegetative growth. If you make sure to water occasionally, but not to over water your plants, you will get those female ratios on the up and up.
Both over watering or drying out of the medium will produce more males. For consistent results in getting more females keeps those mediums moist.
8. Humidity: Now this is the tricky one. High humidity levels only promote fungi and mold development and lowering humidity levels is the way to cure most of this rot but by keeping those humidity levels up in or around the 70 RH factor will help to produce more females.
If you have a low humidity grow room then you should get to hold of a humidifier. Now high humidity levels like 70 RH cause the medium to dry out a lot quicker so you have to keep this under control too. Keep those mediums moist and those RH levels at 70. This will help to improve those female to male ratios. Again, getting them on the up and up.
If you run the 24/0 photo period then do not allow those temps to go anywhere above 85 unless you have an equatorial strain. 75 is the best but going a little lower is not a problem for helping those female ratios. If you can get in at around 65 then those females are going to be popping up all over the place. The problem with this is that some growers like to use the 18/6 photo period and when the lights are off the temps drop from around 65 to 50 and even less. Try not to be below 55 because this has the adverse effect on the plants producing more males than females. Again between 65 and 75 is where you want to be during the 3rd to 4th week of vegetative growth, the preference being 70.
The following is pre LED
Invest in a MH Light for vegetative growth. Dump the HPS bulb for flowering later. I have noticed that HPS lighting during vegetative growth simply sends those males to female ratios all over the place. With MH lamps the females are everywhere. Invest in some MH HID lights. It makes all the difference in getting those females to show more often. This is worth repeating! MH Bulbs produce more females under optimal conditions especially if they are present during the 3rd and 4th week of vegetative growth. Surprising enough you can start seedlings under HPS and it will not have an effect on those female ratios. Again the 3rd to 4th week of vegetative growth is what is important here.
No stress during the 3rd to 4th week of vegetative growth. That is all there is to it. If you got your garden growing in optimal conditions without plant stress then the impressive 90% to 95% females start to emerge from standard seed packs.
I find that topping is best done at the second to third week of vegetative growth but that this is a little stressful and can lead to those female ratios dropping again. Avoid topping or pruning if you are looking to up the female count.
