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Old 12-15-2009, 08:27 PM #1
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Forcing bloom: Manipulating photoperiod for out of season harvest

Mainly I am posting this thread just to see if we can concentrate some knowledge on the subject, there are many threads here with info on the subject, but no regular running discussions.

The subject I am referring to as forcing is also known as "bagging", "capping", "black-out", and a variety of other terms. Basically it is the technique of manipulating the natural photo-period in order to bloom and finish strains out of their normal season. This is accomplished by shortening the day to 12 hours of light by blocking out light, allowing blooming in mid summer or spring.

There are many situations that forcing could help with, I use forcing sometimes to supplement my stash. If my regular Autumn harvest was too small to last through the next harvest, I can start seeds in March, veg indoors one month, move them into a GH by April, force them under 12/12 starting in early May, and have a harvest by July 4th.

I can see other advantages, especially for those with bad outdoor climates, ones that get too cold, and ones that are too wet during the blooming season.
By adjusting the photo-period, a grower could force a plant that finishes in October normally to finish a month or two earlier when cold and mold are not such a problem.

Another grower may want to try a strain that finishes in November or December naturally, by adjusting the photo-period many northern growers could finish tropical sativas before cold prevents it, inside the GH or not.

I once read a story about a college student in the San Fransisco bay area. He converted a old chicken coop into a greenhouse, at the beginning of summer break he'd fill the greenhouse with plants, and in July he'd force them. By the time classes started again he was done and harvested and ready to devote his time to school. And his harvest was done before rippers became a problem.

Another person who may be helped by forcing is breeders, especially breeders who would like to work with potent tropical sativas for the purpose of breeding with shorter season Indicas(perhaps with the intention of adding potency to local outdoor plants).
In some climates a breeder may be able to do 4 back-crosses in a year.

In climates where lots of sunshine is available year round, but the climate is cold in winter, double paned heated greenhouses and manipulation of the photo-period may allow near year round harvests. I have observed many high desert locations in the western USA where this could be done.

Anyways, here is a list of threads I've found with at least some info on forcing:

Where's the Light Deprivation Experts at?

worries for light deprivation

do you think there is a market for a stealthy auto darkining greenhouse?

black boxing info needed

Blackhouse for All-Summer Flowering!

greenhouse blackout

Grobot 2007

Shed force flowerer using a garage door opener?

Nice looking greenhouse design with flower forcing cover

Anyone else here into this? Have something to share? I think this is a under explored subject.
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Old 12-15-2009, 10:50 PM #3
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Nice man thanks alot for taking the time to do this
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Old 12-15-2009, 10:56 PM #4
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looks like a pita carrying plants back and forth, i like the auto darkening greenhouse idea, something like a welders mask that changed the color for clear to dark with a elecrical current.
would be pretty awesome!
or just grow autoflowers
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Old 12-15-2009, 11:40 PM #5
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keeper- no problem! this is a method of growing that is not exploited enough I think.

freeride high- Not sure about the welders glass idea, but other automated systems that close curtains or doors by use of electric motor do exist or can be built.
Personally, I'm a home body, and don't travel much, so a manually operated black out green house would be enough convenience for me. Make it convenient to apply and remove the blackout, and I'm a happy camper.
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Old 01-19-2010, 08:12 PM #6
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I am just finishing up 2 ladies in mid summer down here in SA. They are in pots and I carry them inside everynight and put them in a cupboard at around 6. I then take them back out at 6 in the morning, or maybe a little later. I am in week 7 at the moment and harvest time is any day now. I figure I could flower more if I bring 2 in 12 hours after sunrise and take them back out after sunset. Then bring 2 more in and take them out 12 hours later. So if it gets light at 4am, bring 2 in at 3:45pm to be safe. Say its dark at 7pm, take first 2 out at 7:15pm and bring 2 more in. Take them out after 7:15am. And repeat for up to 8 weeks or more depending...rain covers are a necessity if you have a wet summer and make sure your indoor cupboard is ventilated at least a bit. It is easier to manipulate a plant in winter where you simply need to break the 12 hours of darkness, wait till an hour or so after the sun goes down and shine a bright torch on any of your ladies that you want to veg longer in winter. Keep the light on for at least a minute, I usually go for about five. You could also have an indoor setup and supplement the extra dayligt hours which would only lead to more yield.Where I stay in sa the only bad time to have flowering bud outside is in summer. Like I said, it is the wet season and is humid as hell, bud rot can become a problem if the big nugs get soaked and aren't thoroughly dried. Anyway, I know this is an old thread but I love this technique of harvesting bud mid summer using the power of the sun.
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Old 01-19-2010, 08:24 PM #7
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Originally Posted by TUFFGONG View Post
Anyway, I know this is an old thread but I love this technique of harvesting bud mid summer using the power of the sun.
Peace
This is why I posted this thread, and thats why keeper stickied it, it is here to collect info to help!
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Old 01-19-2010, 11:05 PM #8
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A couple of years ago I started putting a few of my greenhouse girls in empty compost bins so they got 12/12 light/dark mid summer (uk)

Last year I decided to build a 4ft by 4ft blacked out cube at the beggining of the year so it was easyer to cover the plants and fit more in there.

heres a photo of the greenhouse with the 4 by 4 cube I built (it only cost about £3 to build!) the plants behind it are not the ones going in there, they where just waiting for the girls I was covering to finish so I could take the cube down and repot them. the girls I was covering are in the other couple of photos.

My alarm was set for 6am and 6pm 7 days a week, I use to get up 6am everyday as soon as the alarm went off, no matter how tired sick stoned or hungover I was and take the girls out, the bennifit of having the blacked out cube in the greenhouse was I only had to lift the plants a few inchs from total darkness to full sunshine.
Then at 6pm every evening I would put them away, Id put a small desktop fan in with them to keep the air circulating and wait for the morning...

I have some much better photos somewhere on my pc so il have a dig around and see if I can find them, I think these photos where taken about 3+ weeks before the chop. they got REALLY fat





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Old 01-20-2010, 12:02 AM #9
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Very nice dargo! This is very nice! Exactly what I was talking about.

You mentioned that you are in the UK(Britain), so the date stamp from your camera probably reads in the European norm: day/month/year, rather than in the north American norm: month/day/year. So the first and second pictures were taken on July 5th, not May 7th, right? Just clarifying for the Canadians and Americans(USA) reading.

When would these plants normally finish naturally, and when did they finish by forcing? How long did they take to finish once you started forcing?
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Old 01-20-2010, 12:22 PM #10
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Time stamp is day/month/year (uk) so these shots taken in july, mid summer pretty much around the longest day of the year so naturaly they should be in full veg not full flower

I planted the ones I was flowering in my flowering cube at the same time as the taller skinny looking things by the side of the cube, I was covering the flowering ones for about 9 weeks (unsure what strain they was all different bag seeds from random seeds I found in really nice weed and saved)

I had a small (very small) mold problem towards the end and also had to go on my summer holiday after about 9 weeks, they all had milky/amber trichs when I harvested them, if I had a choise I would have let the haze go longer but didnt want to leave a fully flowered plant out while i was on holiday for 2 weeks so I harvested them all the day before I went and dryed them while on holiday, I then got home to my smoke all ready for me.

Of the 5 I let go naturaly (4 in greenhouse 1 outside) 1 finished end of september, the 2 unknow amnesia haze crosses I had in 10L pots finished october/november. I took the top buds off end of october and the rest was picked as it ripened over november, the 1 unknown amnesia haze cross I planted in a 50L pot never had time to finish properly, she had really bad mold all over here, I lost the entire top cola and pretty much every top to every branch :( if she had finished I could have pulled 10+ oz off her easy! I had to dig a 2ft hole in the ground to bury the pot as she was so tall.

I got about 8-9 oz from my flowering cube plants, from the ones I let go on there own i got about 1.5lb maybe

The plant I let go outside I didnt even know was there untill she was well into flowering, I cut a hawthorn down at the back of my house and it was there, must have been a seed I chucked and did its own thing. It was doing pretty well untill the british autum/winter started to apear, she suffered alot of mold, I dint enjoy her taste but she got you STONED!

The results I found are better when you force flowering mid summer, the buds grew much dencer and the mold risk was greatly reduced, im sure if i had better ventilation in the greenhouse I could stop most of the mold.

Still cant find all my photos from last summer but found a few from a couple of years ago when I was using the compost bins and water buts to cover the plants......

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