Hey all I’ve got some plants under a 400w MH they are 7 weeks old. I have a room available with 4000w HPS hooked up to it. Would you keep your plants under the correct spectrum of light or would you move them to more wattage? What would you do?
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I would put them in the room with the 4000w HPS when I would flower them, and the MH for veg.
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@shady The room with 4000w is my flower room. Just not being used at the moment. I’ve never had so much free space haha
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If your like me, all that free space will be filled shortly and you will be looking for more soon lol. I have seen people veg under HPS, its just not very fast compared to MH. How long before you are thinking of flipping them?
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Well this is the question … what what help veg more 4000w of the wrong spectrum of 400w of the correct one.
I was thinking of flipping in 2/3 weeks.
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I would stick them under the 4000w HPS for the 2 -3 weeks and then flip them to 12/12 just to see how well they do. You will know next time whether its worth to do it again.
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I would say put them under the hps the difference isent realy that big even when using equal bulb strength, with that much more hps then mh I’m sure they would grow faster then under the 400 watt metal hailed.
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At 7 weeks of age, I would switch them over pronto to your 400W HPS.
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@Calyxander it’s 4000 w HPS. The plants are still small, I’ve topped them multiple times each so that has slowed them a bit. They still need 2/3 weeks
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Sorry I read that wrong…even brighter light is available, so I would move them sooner than pronto!
I like to put my seedlings under direct sunlight as soon as possible. My basic strategy is to give my plants as much direct sunlight as I can. Indoors I always use the very brightest light I have. But for the past several years I have grown mostly outdoors, bringing the plants inside (under lights) only if the weather is not accommodating, and I never leave plants outdoors overnight.
My meandering point being, that I do not think it is good to “baby” new seedlings with anything less than the brightest light available…indoors or out.
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I’d keep em under the 400, save money and better veg spectrum. Once they outgrow their area I’d chuck em into the big show.
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I’m wondering, what is your current light schedule (for veg)? How much area does the 4000W HPS illuminate vs the 400W?
Without having an estimate of the PPFD, I’d lean towards what @beacher has said with the following add-on thoughts:
Consider sticking with the lower intensity lighting for the remainder of your veg schedule since you are already there. Particularly if the plants are looking healthy. The spectra balance from the MH may do better on a couple of fronts:
- building more compact plants initially due to the higher ratio of blue.
- improved photosynthetic efficiency, the plant is more efficient in converting energy at the lower energy.
With that in mind, to get more “growth”, it may be simply a matter of increasing the DLI for the 400W scenario by extending the time the lights are on. Essentially replicating the higher intensity and shorter period with a lower intensity over a longer period. This (while in veg) depends on how long the light cycle is currently, of course.
**Whether that would be a good idea after having been on a set-schedule, I don’t really know
A downside of moving between the two rooms could be the shock to the plant. Particularly if the DLI at the canopy significantly differs. Being under a lower intensity will also mean the plant will have grown to better utilize the available energy. When moving to a higher intensity, the energy overload could very well stress the plant, cause bleaching, and such. Similar to moving a plant from indoors into the summer sun. In such a case, I’d want acclimatize the plant by keeping the higher intensity lamp somewhat further from the canopy and then adjusting the lamp a bit closer nightly.
Over the longer term, consider trying to determine some of the operating specs for your two rooms:
Depending on the area being illuminated and the PPF being produced by the 400W lamp, determine the DLI. And, the same for your higher intensity area. Optimally, other things being the same, the DLI will be somewhat balanced between the two. That is, the longer day veg light and the shorter day bloom light produce similar DLI numbers.
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I would transplant them to bigger pots and move to the larger room when you need the space. Vegging under the HPS is fine and will get them used to the orange light before the shock of 12/12 hits - I used HPS for veg for years and never had a problem
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Thanks for that great info @Northern_Loki my light cycle Is currently 24/0. The room with the MH is 3x8 and the room with the HPS is 18x9
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@Muleskinner I think I will drop them into the big room tonight.
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