MH bulb for first 2 weeks of flower and last 2 weeks?? Opinions please?

jackm420

jackm420

Active Member
Hey everyone. Going into flowering soon and I've read so many mixed opinions on this matter. Lots of people say to use the mh bulb the first 2 weeks of flower to minimize stretch then swap to hps (I'll be using eye hortilux 400watt) then back to mh the last two weeks for weight, resin, and flavour enhancement. I kind of like this idea but I'm wondering if swapping the mh back into the picture the last 2 weeks would make the plants freak out or shock them and make them herm..I have 2 dutch passion mazar females (medical strain) and one akorn snowbud female. Thanks for any and all advice!!! Thanks also to everyone who has helped get this far!! They are 46 days from seed. Flowering in a week or two. One dp mazar is 16" right now, other dp mazar is about 12" and the the akorn is only 8" =( hoping it will shoot up a bit more in the next week or two as it's a week behind the others and just started grow big nutes since the soil was hot and it was good to go for the first month. I will be flowering them all at the same time. Thanks!
 
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big bud 56

Active Member
There's really no need using mh bulb in flower.
IMO an mh bulb doesn't even need to be used at all.
I use hps throughout the whole grow and have always gotten good yields.
the plant will stretch no matter what.
Good luck
 
AlGore

AlGore

Well-Known Member
I haven't read about using MH the last two weeks but you should keep it during your transition to flower.

I'm only on my first grow but have read a ton and my shit is looking super fire, about to start week 6 of flower.

In my case I left the MH 12" above the tops for the first week of 12/12 then switched to HPS. 400W Hortilux Blue MH / Hortilux Super HPS btw.

I think that any photo cannabis has a bit of a "streach" after switching to 12/12, that is the reasioning to keep the MH in there, to minimize it somewhat and keep your bud sites nice and dense.

PS> If your gonna go one lamp the whole grow, an "enhanced" spectrim hps I've read is not a bad option.
 
S

spek9

Well-Known Member
big bud 56 said:
There's really no need using mh bulb in flower.
IMO an mh bulb doesn't even need to be used at all.
I use hps throughout the whole grow and have always gotten good yields.
the plant will stretch no matter what.
Good luck
Click to expand...
I can with 100% certainty say that using an MH for the first two weeks of flower reduces stretch. I did this test back-to-back with White Widow.

What also helps I find is if you keep using your grow nutes for the same two weeks, so switch nutes to bloom when you swap out your HPS.

As far as the last two weeks of flower, I have no idea. I personally wouldn't be interested in doing such a test, and haven't heard from anyone else who has either.

-spek
 
Sunbiz1

Sunbiz1

Well-Known Member
big bud 56 said:
There's really no need using mh bulb in flower.
IMO an mh bulb doesn't even need to be used at all.
I use hps throughout the whole grow and have always gotten good yields.
the plant will stretch no matter what.
Good luck
Click to expand...
HPS is a yellow/red spectrum, while MH is white/blue.

Under natural sunlight, plants veg in May/June using white/blue light spectrum. As summer progresses into fall, sun spectrum changes to yellow/red.

Indoors, we try to do the same...using an HPS bulb during vegetative growth is not recommended and will cause stretching.
 
jackm420

jackm420

Active Member
spek9 said:
I can with 100% certainty say that using an MH for the first two weeks of flower reduces stretch. I did this test back-to-back with White Widow.

What also helps I find is if you keep using your grow nutes for the same two weeks, so switch nutes to bloom when you swap out your HPS.

As far as the last two weeks of flower, I have no idea. I personally wouldn't be interested in doing such a test, and haven't heard from anyone else who has either.

-spek
Click to expand...
Keep nutes the same till i swap hps?? Fox Farm says to give open sesamie which I have ready to go the week before you flip and for the first 2 weeks of flower. are you saying to skip open sesamie? If I keep the grow nutes the same that would mean a lot of the product grow big which is cut down after veg....not seeing how that would help minimize stretch I would think it would grow bigger..
 
AlGore

AlGore

Well-Known Member
jackm420 said:
Keep nutes the same till i swap hps?? Fox Farm says to give open sesamie which I have ready to go the week before you flip and for the first 2 weeks of flower. are you saying to skip open sesamie? If I keep the grow nutes the same that would mean a lot of the product grow big which is cut down after veg....not seeing how that would help minimize stretch I would think it would grow bigger..
Click to expand...
Hey, I was just reading the new high times and there was a quote from Kyle Kushman in here I thought applied... ;-)

"I recommend vegging under metal halides and flowering under high-powered sodium lights-it helps initiate but set faster, with shorter internodal spacing. This is caused where plants experience a double shock when you change the photoperiod and the light spectrum simultaneously."

So basicly what we were saying. Wait a week or two after changing the photoperied before changing the light spectrum.

As far as your nutes go... I use GH and base my "ratios" off their chart. I have adjusted the concentrations of the differnt componets based on my plants needs. But if you take a look at the FF charts you'll see they are suggisting keeping grow nutes durring transition....http://foxfarmfertilizer.com/frontpage/feeding-schedules.html

Hell, I'm like 5 weeks after transition and am still giving 1ml/gal of the "Gro" nutes.
 
jackm420

jackm420

Active Member
AlGore said:
Hey, I was just reading the new high times and there was a quote from Kyle Kushman in here I thought applied... ;-)

"I recommend vegging under metal halides and flowering under high-powered sodium lights-it helps initiate but set faster, with shorter internodal spacing. This is caused where plants experience a double shock when you change the photoperiod and the light spectrum simultaneously."

So basicly what we were saying. Wait a week or two after changing the photoperied before changing the light spectrum.

As far as your nutes go... I use GH and base my "ratios" off their chart. I have adjusted the concentrations of the differnt componets based on my plants needs. But if you take a look at the FF charts you'll see they are suggisting keeping grow nutes durring transition....http://foxfarmfertilizer.com/frontpage/feeding-schedules.html

Hell, I'm like 5 weeks after transition and am still giving 1ml/gal of the "Gro" nutes.
Click to expand...
right i know about keeping those going but says to add the open sesamie to the mix the week before flowering and 2 weeks after i think that guy was saying to not change it up at all
 
dannyboy602

dannyboy602

Well-Known Member
mh put out a little more uv...mb that's why guys use it. I personally don't.....and I think its the flip to 12/12 that causes stretch. that's my educated guess.
 
B

big bud 56

Active Member
Like I said no matter what bulb you use your plants are still going to stretch somewhat.
personally,I don't mind the stretch.
It just gives more room for the duds to fill up that space.
More stretch= more bud.
 
B

big bud 56

Active Member
one more thing for those scrog growers,I would think that if you're doing a scrog grow then you would want those stems to stretch up into the net.
 
Bakatare666

Bakatare666

Well-Known Member
jackm420 said:
Hey everyone. Going into flowering soon and I've read so many mixed opinions on this matter. Lots of people say to use the mh bulb the first 2 weeks of flower to minimize stretch then swap to hps (I'll be using eye hortilux 400watt) then back to mh the last two weeks for weight, resin, and flavour enhancement. I kind of like this idea but I'm wondering if swapping the mh back into the picture the last 2 weeks would make the plants freak out or shock them and make them herm..I have 2 dutch passion mazar females (medical strain) and one akorn snowbud female. Thanks for any and all advice!!! Thanks also to everyone who has helped get this far!! They are 46 days from seed. Flowering in a week or two. One dp mazar is 16" right now, other dp mazar is about 12" and the the akorn is only 8" =( hoping it will shoot up a bit more in the next week or two as it's a week behind the others and just started grow big nutes since the soil was hot and it was good to go for the first month. I will be flowering them all at the same time. Thanks!
Click to expand...
Overkill bro.
No need for all that.
These are 12/12 from seed under CFL's 6 and 7 1/2 inches tall, at 33 days old, no stretch, and they've already almost filled the 4" pots.Nov29ECSD2and3_zps2ec4e570.jpg
 
AlGore

AlGore

Well-Known Member
jackm420 said:
right i know about keeping those going but says to add the open sesame to the mix the week before flowering and 2 weeks after i think that guy was saying to not change it up at all
Click to expand...
I see, I misunderstood. Not familiar with the fax farm line(although I do have a massive plant in some FFOF atm).

Looks like open sesamie is an additive specifically designed to help initiate bloom and "enhance" the early flowering process. So if I was basing my feeding of their chart, I would go for it.

The thing your trying to avoid the most is stress or shock. So you don't want to add new nutes, change the photoperiod, and change the light ALL at the same time. So they have you start it on the OS the week previous to changing the photoperiod, and continue that untill after you have switched your light spectrum. Makes perfect sense.
 
AlGore

AlGore

Well-Known Member
Bakatare666 said:
Overkill bro.
No need for all that.
These are 12/12 from seed under CFL's 6 and 7 1/2 inches tall, at 33 days old, no stretch, and they've already almost filled the 4" pots.
Click to expand...
I'm not sure how that applies. He's said he's currently vegging under MH. And wanting to switch for flower. The one thing you def don't wanna do is flower under MH if you don't have to.

fyi... 35 days from clone under 400w MH: http://needmodro.wordpress.com/2013/11/28/veg-week-5-day-1-lots-of-closeups/
 
A

althor

Well-Known Member
The reason some people say to switch back to MH the last two weeks is for UVB.
The only thing about that, a MH bulb (especially in an air-cooled hood) puts out such small quantities of UVB that it won't make any difference.
 
A

althor

Well-Known Member
big bud 56 said:
Like I said no matter what bulb you use your plants are still going to stretch somewhat.
personally,I don't mind the stretch.
It just gives more room for the duds to fill up that space.
More stretch= more bud.
Click to expand...
Nope.

More stretch = more stretch in your buds as well. So instead of hard, compact colas, you have long airy buds filling in gaps.
 
bullSnot

bullSnot

Well-Known Member
18/6 With MH then 36 hours dark
Flip to 12/12 with MH for 7-14 days (tighter buds)
Then go HPS for the rest of flower
 
nfhiggs

nfhiggs

Well-Known Member
Sunbiz1 said:
HPS is a yellow/red spectrum, while MH is white/blue.

Under natural sunlight, plants veg in May/June using white/blue light spectrum. As summer progresses into fall, sun spectrum changes to yellow/red.

Indoors, we try to do the same...using an HPS bulb during vegetative growth is not recommended and will cause stretching.
Click to expand...
The suns spectrum does not significantly change in fall. There is a SLIGHT shift towards red at mid-day (compared to a summer mid-day) as the sun is not as "high" in the sky at noon. But the same shift occurs on a daily basis each afternoon in summer as well. The reason MH is used in flower is the bluer light results in tighter node spacing, as it breaks down auxins in the plants stems. HPS is used in flower because its about 30% brighter/more efficient than MH.
 
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