Switching to MH last weeks of flowering?

I did it before but didn't notice any difference

I guess everybody got to try it for them selves and it probably takes a couple crops for spmepne to catcup wit wats the diference

hyroot said:

the sun never changes spectrum. You want the same spectrum through veg and flower.

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You are absolutely wrong on this one. During summer sunlight is blue, and towards fall the spectrum changes to red hues. Even changes during morning, midday and evening are huge. You can't seriously claim, you've never seen a sunset that makes the sky and your surroundings glow orange.

The sun doesn't change but the angle of the earth does and thus the atmospheric effects change. This is why plants evolved to use red spectrum for flowering.

As far as metal halide, it does make for more resin but at the cost of yield.

Same theory as 10000k CMH finishing bulb for higher resin production. all that awesome UV.

I got 3000k & 6500k bulbs, and grow with E27. I'm using 3000k now, but do you think there would be any benefit to switching to 6500k (445nm) the last week of bloom?

No idea why this thread was dug up lol

JSheeze said:

I got 3000k & 6500k bulbs, and grow with E27. I'm using 3000k now, but do you think there would be any benefit to switching to 6500k (445nm) the last week of bloom?

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Can you do both lights? If only one, I'd stick with the 3000k. I tried switching bulbs a couple years ago; wasn't much of a difference to me. But if you flower with a blue spectrum, you do get frostier buds; but as Renfro stated above, you will yield less.

Originally...


Switched at 2nd week of bloom to all 3000k...


You recommend going back to original?

The 6500k are only 20w, while the 3000k are 30w.

T macc said:

No idea why this thread was dug up lol


Can you do both lights? If only one, I'd stick with the 3000k. I tried switching bulbs a couple years ago; wasn't much of a difference to me. But if you flower with a blue spectrum, you do get frostier buds; but as Renfro stated above, you will yield less.

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This is a very interesting and valid conversation which needs more feedback.

Hps gives off zero uvb. Zero. In weeks 3-5 hps will help bulk the flower production, but cmh is the best. Using a blue 10k MH to ripen does help alot. So does uvb lights. HP's creates a lot of heat and unusable light spectrum. When I can I'll be switching to all CMH and blue MH to finish. Getting rid of all the hps bulbs forever. And don't forget terpenx the last week of flower. Check for odor problems the day after. Adjust your exhaust air schedules to avoid detection. Seriously.

This is neat stuff that I knew nothing about. Would it be advisable to swap one of my 3 lights from hps to mh during the last week or 2 of flower? It'd be really nice if I could increase the potency of these autos I'm growing now.

Lenin1917 said:

This is neat stuff that I knew nothing about. Would it be advisable to swap one of my 3 lights from hps to mh during the last week or 2 of flower? It'd be really nice if I could increase the potency of these autos I'm growing now.

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Best is to use as full spectrum as possible from start to finish. I run one flowering tent with 600w HPS and 315w CMH and one tent with 800-1200w 50/50 or 60/40 HPS/MH.

You want the UVA the MH bulbs provides. You don't need much as supplemental. 315w CMH fucking rocks when it comes to providing a complete spectrum and CRI. You can run them very close to the canopy and they don't run very hot. Best mounted vertically. Cheers!

I always had 1 MH in the flower room for years. Then I went 100% HPS when MH ballast died. I then started to notice my weed had less smell. Took quite a few crops before I figured out it was the missing MH light. All it takes is one MH light to throw a little blue light around.