flowering period

[BaronS]

just wondering what people may suggest about longer (or indeed shorter) 'day' periods for flowering.

 

is 12/12 optimal?

[TD.]

its a balance between giving the plant enough darkness to build up a hormone that triggers flowering and giving it enough light for photosynthesis. personally i go 13dark and 11light.

[smokinjoe]

I usually flip them to 12/12 and if a couple of weeks out from flowering switching them to 11/13 then 10/14.

[BaronS]

hey smokinjoe, do you mind expanding as to why you do so?

 

Let's be specific. The way I read it you flip to 12/12 then reduce the 'day' period further, and then further again. WHY?

 

I've never actually experimented along these lines but was thinking about doing so. My idea is to give the maximum amount of daylight hours that does not interfere with flowering.

[smokinjoe]

IME dropping the hours of day light after it has essentially finished bud development seems to speed up the finish time. It also conserves 2kw hrs of juice per day with no detrimental effects noticed.

 

No rigourous scientific testing has been conducted I guess.

[BaronS]

hmmm, my thought was that photosynthesis is still happening so by providing as much light as possible without forcing the plant back to veg one would get best result.

 

I think I need a 3rd cupboard so I can compare results. Not totally out of the question.

[need4weed3]

Growing with an 18 hour Day/Night Cycle

 

The Theory

The theory behind the 18 hour Day/Night cycle is that during a normal 24 hour light cycle plants will usually acheive high growth rates peaking at 100% capacity during the first 50 - 60% of the day. The growth rates will then diminish rapidly and the last 20 - 30% of the day acheives minimal growth. So by reducing the length of the day we are triggering an increased growth mode where the growth rates are at their peak for the majority of the day. This effectively achieves a very fast growth cycle with full yield potential.

 

NOTE: To achieve these incredible growth rates it is important to provide maximum light intensities and CO2 enriched conditions. The recommended lighting is 600W per square metre.

 

The Cycles

Vegetative Cycle - Lights ON 14 hours

Lights OFF 4 hours

Flowering Cycle - Lights ON 6 hours

Lights OFF 12 hours

 

The Benefits

The growth acheived during an 18 hour cycle can be the equivalent to that acheived during a 24 hour cycle. So by running 18 hour cycles the same growth and yield can be acheived in 75% of the time.

 

Reduced day lengths also mean reduced power consumption. Grow more and use less power. Who can argue with that?

 

For example, an average crop grown from seed using a 24 hour day/night cycle will have a 4 weeks grow cycle and an 8 weeks flower cycle. This equates to 28 days @ 18 hours a day and 56 days @ 12 hours a day = 1176 hours of light over 12 weeks.

 

An accellerated crop using an 18 hour day/night cycle will achieve the same yields using a 3 week grow cycle and a 6 week flower cycle. This equates to 21 days @ 14 hours a day and 42 days @ 6 hours a day = 546 hours of light over 9 weeks resulting in a 40% reduction in power consumption and a 25% reduction in crop time.

[BaronS]

Interesting. I couldn't do an 18hr cycle with my current timers, or at least not without manually adjusting each day, may as well be flipping the switch manually. I guess timers that could handle such wouldn't be too expensive though.

 

The idea that the majority of growth happens in 50-60% of your day would seem to suggest that on a standard 24hr cycle there would be little or no benefit 13 vs 12. In fact I'm now questioning the value of my current 20/4 veg cycle.

[smokinjoe]

I was of the opinion, based on what i've read, that the majority of root development occured during dark periods, I guess when the plant is not concentrating on photosynthesis and growth.

 

This is why I have always gone with an 18/6 veg, I've never noticed any significant difference in growth to justify the extra 6 hours of juice.

[dsyfer]

I was told this morning, that a good way to give plants a kick start into flower, is give them a solid 48 hours of light followed by 24 hours of dark then into 12/12, anyone heard of this way before?