going from mh to hps

[ROLNIK]

When ya veg under a mh, and ya put'm straight under a hps for flower,, do the plants notice the light change?
They are droopy when lights off forsome reason,,just put'm in 2 days ago, never noticed this before, its the firsttime I did any vegg'n under mh,, and then to hps for flower. thx

R

[sookieme]

some even say they notice it enough that it helps enduce flowering faster

[Guy_In_Pain]

I agree with sookieme they can definately tell the difference. They will be fine.

[ROLNIK]

Shit man,,,, never saw it before,,, they look'd like 2,, 3,,, hours late for water'n,, lights on normal Thx,,,


R

[Guy_In_Pain]

Is there much difference in wattage between the mh and hps? ie 400 w mh to 1000w hps? This could have a bigger impact on that look and if that is the case back off the light just a bit maybe 6 inches or so until they get more acclimated to the bigger bulb.

When I first flip mine over (bring a new plant into the flower room I run perpetual) I usually give it some distance between them and the big 1000w. I veg under 400w mh so there is many differences other the light spectrum. The light intensity is X3 for one.

[lightly_toasted]

My plants do it as well when I go from under the t8's to the 600 HPS. So far I haven't had any issues come of it.

LT

[ROLNIK]

Veg is a 400mh travel'n 3' over a 6x3 bed. About 6 to 8 inch up. 5sec. delay each end.
Flower is two 600 hps side by side travel'n 2' over a 7x3 bed. About 10 high, 10 sec. delay each end.
All have adjustawing copys for reflectors.

I was a lil concerned cause I just went to a 18gal res. for water'n. lil motorhome pump,,, nice,, and makes dump'n 10 to 15 gal. a snap. Mix a lil to much fert in so to speak,,,, ph was squatted pretty low also,,,, lets ,,,see,,,, 10gal,,,,, 8 gal,,,,,, 5 gal,,, 3 gal,,, with an 18 gal res. comes out too,,,,,,, I'll getit,,,, good thing their tuff like a Ford,,,,,,
Thx

R

[ROLNIK]

So 3 weeks under the mh,,,, 12 on, 5.5 off, 1 on 5.5 off.
With my limited understanding of what makes the plant flower,, during dark time the plant reads something to tell it to flower,, so if the length of dark is not broken, flowering will happen. By breaking the dark time exactly in the middle,, 5.5 hrs,,, it keeps it from flowering. What happens if you break the dark time like at 8 or maybe 9 hrs for 1 hr? Would it flower cause the actual dark time un broken be to long? Was thinking of try'n this with the next crew going into flower end of next week 12 on, 9 off, 1 on, 2 off just to see what happens. If it doesn't herm them,,,think'n maybe it would be more ready to flower when I did put them in at 12,,,12. I kno why change what works,,, just wonder'n..
Thx R

[chillzpls]

http://en.wikipedia.org/wiki/Photope...ort-day_plants

I doubt it. After you give it that "longer dark period", it's going to be immediately followed by a shorter one again of 2h off and 12h on, and you'll just pre stress it.

When you swap to HPS a number of things will change, light quality which is the spectral distribution and this does help trigger flowering hormones, irradiance, and quite likely temperature, which will also mean greater temp differentials between day/night and that also tells the plant things (stretch/turn purple).

An increase in intensity alone, from say 400W to a 1000W, will kind of shock it and it needs time to acclimatize to the increased irradiance levels. That's why when people move an indoor plant outdoors under the sun, they stick it in the shade for a few days and let it "harden". If they didn't do that, it would probably die.

That's why guy_in_pain gives his freshly swapped plants some extra distance from the light for a few days, as it limits the shock while they harden off.

But there's still all the other changes they'll see as well and will have to get used to regardless, like the temperature changes and the sudden change in light quality.

I think it would make more sense to try swapping to HPS before you switch to 12/12, and so you acclimatize the plants to the light's irradiance levels, quality, and new temp differentials, prior to inducing flowering, if you really think it's that big a deal.

[ROLNIK]

I dig it,,,, thx. They do act up now when I put'm under the hps, using the mh veg.I'll give it a try on the next set going into flower. How long you think I should pre run'm under the hps?

R

[chillzpls]

I dunno. People usually give them at least a few days to harden up to higher irradiance levels. So I'd expect a few days, but keep a close eye on them while they go through it and they'll tell ya what's up.

[ROLNIK]

So,,,, I think I'm digg'n on this mh to hps. The ones I dump'd in flower on Jan. 2nd seem to got it go'n. Small buds pop'n nail size at 10 days light so far,,, prior run,, 400 hps to 600 hps took 15 days of light to get this far.
One other thing is,, they seem'd to stretch a lil faster, that might relate into taller stock. Is it common for the added stretch also?
So,,,, one of two things must be happ'n here,, either I'm gett'n good,,,, (would like to think so,, but highly doubt it) or the mh to hps is click'n.
Thx

R

[Guy_In_Pain]

The plants will stretch more under hps compared to mh IMO. Give the top 2-3 inches a pinch so you crush the stem between thumb and forefinger, gently until they flop over. No worries they will bounce right back in a day and continue to shoot for the stars. You can keep doing this for the next couple of weeks during the "stretch phase" and it will strengthen them and allow for bigger buds when they finish.

And you are probably getting better as you go it will happen.

[chillzpls]

Your flowering hormones develope at the top of the plant. I'd think if you pinch while stretching it'll be messing with that hormonal process.

Stretching is controlled by temp differentials; too great a difference between night and day induces it.

It's also induced by light quality, which is the frequency distribution. That gets a little bit complex, but generally people discuss the red to far red ratio.

As well, a complete lack of blue light will promote stretching, or perhaps more accurately some blue light can help control it.

Some plants will stretch perpetually if you have a very poor quality HPS light that only has a very narrow band, and so poor red to far red ratio with no blue to speak of. The red to far red ratio controls the shade response, making it think it needs to stretch for more light because it's starving in the shade.

You'd be better off growing with a more complete spectrum overall. A mix of HPS and MH, or CMH, or CFL or a mix of HPS and CFL...

Like if you kept your HPS but added a 100W of CFL light as side lighting, you'd be doing your a plant a whole shitload of good, and for a lot of different reasons.

You could also expect improved potency and flavor, since that's controlled in the blue spectrum of light which even super expensive "horticultural" and "spectrally corrected" HPS lights, just don't have.

HPS was used because it emits very powerfully and very efficiently, but only in a very narrow band... also of a spectral content that helps promote flowering. But it's far from ideal and doesn't produce high quality, great for yield though.

[ROLNIK]

Ya,,got it man,, makes sence,, my temp diff. this winter is like,,, 62,63 nite,,, up to 82 day. hav'n a hell of a time gett'n it dial'd. Been warm out,,, then cold as a well diggers rear,,, back to warm,,, by warm I mean 32f.
Try'n to save a lil heat sall.
Thx

R