When to switch to HPS?

So I am about a week from switching to my 12/12 schedule and I am currently running a 400w MH bulb. I also have a HPS bulb for flowering.

I know that I am supposed to ease back the time to get to 12/12 from 18/6, but when do I actually switch out the bulbs?

Is it as soon as I start to switch over or should I let it sit under the MH bulb for a week or so at 12/12 before putting in the HPS bulb.

Thanks!

when u start 12/12

Have to admit that i have never "eased back" from 18/6 to 12/12. Maybe i do it wrong . HPS when you start 12/12 . I have read before to leave in dark for 24h prior to starting 12/12 but i have just flipped in the past.

WaveriderNW said:

I know that I am supposed to ease back the time to get to 12/12 from 18/6

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Switching to 12/12 is what we call "forcing flowering." Rather than let the plant mature naturally under normal outdoor lighting timeframes, you are "forcing" it to flower. There is no "easing back" involved. For you, the last vegging day is 18hrs long and the first flowering day is 12 hours. The more suddenly the first 12hrs of dark occurs, the faster the plants will begin to flower, with exceptions. This is one of the reasons for vegging under 24/0. It can shave a little time off flowering by getting the process going a bit quicker.

And Wyte is of course correct about the bulb change.

Thanks for the tips!

I guess I meant more of taking no more than 3-4 days to get to 12/12...like take an hour and a half off each day. I thought imitating the shorter days of Fall would signal flowering...but I like the sound of "Forced Flowering". The faster I can get to the fun part the better!!

I am running MH for first 2 weeks of 12/12 testing to see if it reduces the initial stretch, It will be right next to plants under HPS of same strain and age so i have a control group

RawBudzski said:

I am running MH for first 2 weeks of 12/12 testing to see if it reduces the initial stretch, It will be right next to plants under HPS of same strain and age so i have a control group

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Yes it does

Well.. I will be using MH thru the Entire Flower Phase and a HPS. next to one another. Will be Rotating the plants every other day until harvest. Trying to get the best of both worlds.

RawBudzski said:

Well.. I will be using MH thru the Entire Flower Phase and a HPS. next to one another. Will be Rotating the plants every other day until harvest. Trying to get the best of both worlds.

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Your plants will love you.I know i used a mh on this grow right now for about a month and hps for the rest.My plants look crazy frost and did not stretch much at all during flowering just packed on weight

Woo, good to hear. I havnt been able to find much imput on it so thx. I hear MH can help produce more THC or potency..

wyteberrywidow said:

I know i used a mh on this grow right now for about a month and hps for the rest.

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You used a MH a month at the beginning of the grow, or a month into flowering?

I switched from 400MH's to 600HPS's about a week before starting 12/12 just so I could nail down the extra heat. Next time I'll switch to HPS a week after 12/12 just to see if it makes a difference.

WaveriderNW said:

You used a MH a month at the beginning of the grow, or a month into flowering?

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A month into flowering and i also used mh on seedlings with o problems

When im doing my 400 watt Mh i let them rock 18/6 for 30 to 45 days then... when the lights are out i fix my timer to 12/12 then i make sure all the lights are off an cool then i put in my HPS... wait about 7 days for them to show there sex... keep the hairy ones " aka females " an cut down the ones who have balls...