endo pendo

OK, thanks for clearing that one up for me Ben. I must admit, I kind of quickly browsed through that one

Yea, I agree with you. That's the point that I was trying to say is that this is really splitting hairs, and either way will work just fine.

pendo

bgetting

I guess this didn't come across well earlier, either. The plants do need a rest period. Chlorophyll is not a magic molecule that cannot be damaged. It will overload and be damaged, which is the reason behind photorespiration. During the dark cycle the plants use the sugars that the synthesized that day. It has never been shown that there is an increase in root growth due strictly to a lack of light for hours a day. That is dependent on other factors. It is good to let them rest for a short time each day, partly so that they can maintain their natural circadian rhythm, but also so that membrane potentials and other gradients built up through the light period can have a chance to disperse, just like in nature. Use 24/0 if you like, but any botanist in the world will tell you that after a certain cut-off period (18 hours for MJ) over which is wasteful. 18/6 is ideal for huge lighting set-ups, but I think 20/4 is a good idea.

People are attributing photoperiod to affect a whole slew of things that it just doesn't affect. Sex being one of them. Although complicated, sex determination is not determined strictly by photoperiod during veg, especially if all other factors are equal. It just doesn't work that way, as in nature there would be not info given from day length that would tip the plant as to which sex would be better. Other environmental factors do.

If someone out there has any data that can shed light on this, I wouldlove to see it posted. Otherwise I guess we will have to rely on the fact that MJ isn't that different from any other plant, and currently most data supports a rest period.

Spaceman_Spliff

Cool.

Would 20/4 be best for a setup with fluoros aswell as for HIDs? I've got a fluoro setup (low budget). 20/4 sounds like the thing to do, regardless of what lights one is using. Is that right?

I do have the info on environmental conditions which influence the sex of the plant, but I forgot to look for it yesterday. Hopefully I'll stop being a basehead and remember it tonight.

Later -~

hkitty420

this is interesting..now I'm a little worried. My plants have been in veg for about 1 month now...7 plants under a 270 watt son agro (about 5900 lumens per square foot)...(actually, for the first few weeks they were under a 250 watt MH and then i switched to the son agro, which they REALLY like). Anyway, from the beginning i've had them under 16/8 because i live in an apartment and i'm worried about a maintenance person coming in while i'm at work or something and seeing it ...or a fire hazard(i have pets) (i'm very paranoid!)...the plants are about 4"-6 1/2" and at about the 5th-8th internode(all have been topped and have great axial growth). Now I know my plants are growing more slowly than most people. is that because the lights are 16/8??? i don't mind waiting longer..I just don't want to stress my plants, or make them be too small in the long run because of this. is 16/8 going to be ok until i switch to flowering and how long do you think it will take until i can flower with the lights being 16/8????? at this point is there any reason i should try and switch to 18/6 or 20/4??? thanks...sorry so long!!!----hkitty

skunk0526

In general this is what i've gotten out of this thread so far in short:

24/0 may stress plants
20/4 optimal
18/6 growth slows, but continues. Least stress? Possibly less potency?

In my opinion,If you're not in a hurry and security is a problem, I would definitely stay where you're at. It's not worth getting caught just for some head bud.

As far as flowering, you should usually wait till they get to about 12" or so. You should have minimal stress making the transition from 18/6. Flower them separately if you have to. That way you'll always have a flowering plant.(If they're not all growing at the same rate.)

At the rate they are growing now, it will probably be at least another 2-1/2~3-1/2 weeks before you hit 12".

*Hints: Lots Of Love
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Do what they tell you.

Do you have a fan on them? It's probably a good idea at least when you're home. You can get a small quiet one that clips to anything at wal-mart.

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SKUNK0526

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UncleBen

Kitty, I think you need to add a few more hours to that 16/8 photoperiod, and no, there are more issues contributing to your slow growth than your photoperiod schedule.

Like I said, a 20/4 is a great compromise regarding the value of a dark period and it's affect on plant health as reflected by bgetting, it does save you a few bucks over the long haul, it gives the garden and equipment a chance to cool down which is very important to me, and I have a thread somewhere that DOES show that too much of good thing can be bad.

Now, would someone please point me to the idiot who made up this odd ball 24/7 photoperiod? Sounds like HT cheese to me and is still promoted amongst the "elite" groups hehe. I'll be glad to show him/her that 22.228/9.984 photoperiod is MUCH betta :-) Thanks but no thanks, think I'll stick to an au natural 24 hour period.

Ah see da light,
Ben

greenskeeper

There are many different things you'll read on the net, and I'm going to share a few with you in addition to some strange things that I've experienced. One source says that an 18/6 period is good because once you get past 18 hours of light, there isn't much difference between turning the lights off then or letting them go the extra 6 hours. As I've said on my gorw site, if there is little difference, then there is some difference, and I agree with the 24 hour lighting which allows the plants to grow as big as they possibly can. I've heard from a source that when you're flowering, if you have the lights on for 12 hours and off for 12 hours, you can interrupt the off time with one hour of light and it's supposed to make more females. I've never tried that, but apparently cannabis plants can change sex at any time before they are in full bloom. This brings up my next point. I planted a few seeds at the end of the last crop's flowering period and they were born into 12/12. They were too small to flower, but they grew like they were trying to develop a large top cola. As a result, they're now in 24 mode and there are 8 internodes in 1 1/4 inches. These babies are really bushy and they're only about 4 inches tall. The only problem with them is that they started making premature male flowers which I knocked off to try to discourage them from that, and they're now making female preflowers higher up. I'm hoping they don't go herm on me, but I will have to wait a couple of months until it's time to flower them to find out. If you do run into hermaphrodites that have the female and male flowers on seperate branches, try cutting off the male flowers and keep the female buds. Some females will make one or two male flowers if they get desperate for pollenation and when you cut these off, it works well, so why not on larger scale too? Also, another point about the timings on the lights- my closet gets pretty hot since I've got a few of those double 4 foot fluorescent tubes going as well as a couple of those neat coil fluorescent bulbs. The coils heat up a lot more and get the closet pretty hot even with the fan going, so I've taken to using them for about 18 hours a day, not in a row (this is where you can use a timer for something other than flowering), and leaving the big tubes on constantly. The heat from lights can wilt and even cook the plants while they're trying to grow so watch out for that. I'm assuming that perhaps the 18 hour light period might be along the lines of keeping too much heat out of the grow room as well as saving money on electricity. If you want to try something even weirder with flowering, you can set your timer differently every day so that you go in 8 hour intervals of light, so that there will still be 12 hours per day of light and dark, but they won't be all in a row. This might fool the plants into flowering faster and getting the harvest done a third of the time sooner. It might also make the harvest a third smaller. I've never tried that but I'm wondering if it might work, and what the results would be. I hope this helps you some.

Afghaniman

Have read all posts and must say that there is quite a contraversy on the number of hours used for foilage growth and determination of sex. I have in the past used books but only as a guide and not as the written rule of thumb so to speak. (You must remember,It's another persons opinion thats all). As far as my (opinion) goes, 24 hrs. is the only way to go. Getting them to 12-18 inches only takes 2-3 wks or less depending on strain which is very important!!! Indicas are slower than sativas as far as growing height so be patient. I myself prefer an indica/sativa cross, therefore I have the best of both worlds. As far as male/female ratio goes I have had excellent results (females) planting in soil with high nitrogen,phosphorous,and low potash levels. Buy a soil test kit and check your soil definetly or your just guessing and that could be devastating to the final result. Your PH needs to be nuetral and is also very important. The last thing I'm gonna say before I go, Simplify, don't make it hard and stick with the basics. You'll be a less stressed and a much happier grower. Thats what its all about.

Spaceman_Spliff

Okay, sorry it took so long, but I found the info on what enviro conditions encourage the development of females. This is straight out of the grow guide that comes with Marc Emery's catalogues:

"With good conditions in a natural outdoor field, you would see only a few male plants compared to the number of females, since the males produce a lot of pollen ensuring plenty of seeds. But if the conditions should be less than desirable more males will emerge, making sure that if there are not many plants that are able to grow, you only need one female to produce thousands of seeds. Conversely, if female plants remain unpollinated they have the ability to produce male flowers and pollinate themselves ensuring their survival.
It doesn't appear as though the sex of these plants is predetermined. It's not like some seeds will be males and some will be females. We know that they all can be either, containing all of the genetics of both sexes, and we've seen them change from females into males and males into females.
The Dutch Passion Seed Co. has done a lot of research and tests in developing their all-female strains. Here's what method they found promotes the most female growth;
-Higher nigrogen content in the seedbed
-Lower potassium content in the seedbed
-Higher moisture levels and humidity
-Lower temperatures
-Less hours of light per day, i.e. 8 hours for the first week or two.
-More blue light like metal halide or fluorescent
Coincidentally enough, this emulates the great outdoors in the springtime.
This info also leads us to believe that sex is determined only by environment and the plant decides when it comes through the soil. We generally are being too kind to them...almost opposite what the tests reveal.
The ability of the plant to change sex is used as a survival technique. When clones are taken from a female plant that has been grown in the vegetative stage for along time, they may have a tendency to produce male flowers near the end of flowering indicating the stress they feel from not being pollintated and producing seeds for the next generation. This can be compounded by changes in environment and the general health of the plants. The resulting seeds from hermaphroditic pollination tend to be more prone to being hermies if the conditions are not right or stresses exist when they are grown."

Those are Marc's words; not mine. They make sense to me. I don't think the enviro conditions affect the female/male ratios all that significantly, but it's best to get all the help you can get to have the most females possible.

-~

DirtyGreenMofo

I grew my plants under 24 7 lighting for about a month and a 1/2 then flowered them with no draw backs. The plants responded to light change within two days, 2 plants were male and three were female. Now that they're flowering ive got them set to 12on 12off. I think this is the best way because the plants are almost shocked into flowering.

DGM

p.s. I got lots of pics to get developed