G'day

I've read that ultimately a grower should use 3:1 mh:hps for veg and 3:1 hps:mh for flower.
Could you achieve the same thing by running a light for 3 days on mh then 1 day with hps for veg?

Cheers
Grinch

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For the most part yes, but there are better ways to time it based on the plant's priorities. For instance in the last week or 2 of plant flowering, the plant focuses less on stretching and more on resin production. This is why for the last week or 2 of flowering, many people like to switch their HPS for Metal Halide. Yield is reduced only slightly but resin production is increased by a good deal. In general, it's good to use both blue and red spectrum lights, but you always want to emphasize a spectrum at a time the plant uses it the most, rather than in a set proportion.

could you give some more details on this? I am looking at running dual 400's on MH and one HPS concurrently, with the MH over the newest flowering plants (for say 4-5 weeks) and the HPS on the other half of the room for the last 4-5 weeks. I would love some more info on this.


p.s. I hope I am not thread jacking here.

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The plants in veg closer to the HPS would probably stretch more (not just because they are farther from the HPS). The plants in flower closer to the Metal Halide would have more resin and probably be a little bulkier. In general all the plants would benefit from the mixed spectrum. However, if you're growing just as many plants from fem seeds or clones as you're going to flower then you might as well use a smaller Metal Halide because the plants will be smaller so you can keep them in smaller containers and use a smaller light. However, if you're using unfeminine seeds than I'd suggest using the same wattage MH with 2x as many plants in smaller pots. Once you identify the sex, you'll be getting rid of about half, and then you can put them in larger containers under the HPS.

thanks for the help guys.

redeflect, I have a 400w electronic ballast and am growing 1 plant under it. I am growing for quality not yield so extra resin would be awesome, so thanks for the tip for changing to a mh for last 2 weeks of flower.

do you have other examples of how to time changes to optimise my grow.

Thanks Grinch

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The switch to metal halide at the end of flowering is new to me, I only recently learned of it (but it isn't disputed). The only other things I can think of, are already pretty well known... 2 days of darkness at start of flowering to "jump-start" flowering. Flower nutrients 1 week after flowering cycle begins... nothing that most people don't already suggest. Using blue lighting at the end of the flowering phase makes sense, I just never thought of it until I read about it recently. Most people want yield rather than quality, and that is why it isn't mentioned often.

It all seems to be fairly logical and not so crazy. I am thinking of running the 800 watts (2x400's MH & HPS) in the same room at the same time. I don't know how the 50/50 mix could be bad, MAYBE a bit of an over kill on the MH but what the hell. Thanks for the knowledge Redeflect.

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Toe-may-toes are good for you.

i posted the same thread a few weeks ago. it would be a great idea. no it wouldn't be overkill either their is no such thing as overkill on light. you just have to try extra hard to keep the temps down. the ONLY dispute i really see is that 600w lights would be better lumens/watt ratio and thats if you want to be 100% efficient +more for yield. so what you lose in one spot slightly(yield) you gain in another(extra bag appeal, potency, resinous).i have seen plenty of people mix spectrums for cfls and get some great looking stuff. yield was not high bc they were just cfls but this is exactly like doing that but with much more powerful light(so yields will be better). so running the mh during flowering is suppose to help because uvb slowly kills the plant(not enough to notice) so the plant reacts ie starts producing more resin to protect itself. plus the mh promotes bushy growth and that will be good in flowering to prevent streching. then you add the hps in there and that gives it the light it is actually craving for (more like 3000k spectrum) so it throws you more bud. so you do the math my friend mh +hps=

Loghead

i always was told that in flower the trick is a 600 HPS and a 400 MH at the same time

Thanks for the good answer Loghead, I was thinking the same thing. I had not heard of the 600/400 ration but obviously that gives you 1k 200 more watts. These 400's where gifts, so the 600 is out.

thanks and sorry for the thread hijack. my bad

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I like tomatoes, all of my posts are about growing, harvesting and drying tomatoes.
Toe-may-toes are good for you.