how far should my HPS be away from my plant when i go from Veg. to Bloom?

Going in soil in smart pots. Tomorrow I am flipping them from my T5 grow light to my 1000w HPS. Whats the distance I should have my HPS and the tops of my plants? Thanks

Kinda depends on whether it is bare bulb or air-cooled. I do air cooled hoods and aim to have the glass about 18 inches from the canopy.
You should probably start them out further away than that though and acclimate them to make sure they dont burn..since theyre used to floros.

BustinScales510 said:

Kinda depends on whether it is bare bulb or air-cooled. I do air cooled hoods and aim to have the glass about 18 inches from the canopy.
You should probably start them out further away than that though and acclimate them to make sure they dont burn..since theyre used to floros.

Click to expand...

gotta love helpful folks like this^^^

You want the lights as close as possible while not being too warm on your plant's canopy. You can use your hand as a gauge...if you can't continuously hold your hand there comfortably, then it's too close to the plant. Dude above mentioned having air cool lights...they do make a huge difference. How much air you move through the lights will also make a difference...moving air at a real slow rate may qualify as "air cooled lights" but it ain't going to do sh!t for you. Centrifugal fans are cheap and last a while too. I use 6" 425 cfm (<$100) fans that work well. My next chance, I'll upgrade my hoods to 8" and fans to 8" so I can pull more air faster through the lights.

You can also bring in cooled air through the lights by bringing air in from outside...assuming the air outside is cool. One thing to be careful here is the humidity that's outside, it can create condensation in/around your hood...bad for multiple reasons. You can fight that by moving more air faster through hood.

At least 36 I Che's until they acclimate. That's a big spectrum and intensity shift. As they acclimate lower the lights or raise the plants to where it doesn't burn the back of your hand then add about 4 inches to that.

That is a decent guide but its data is off and 40k is too much

You technically can't supply too much light indoors to a plant as long as it's got the root system to support the increased photosynthesis and respiration. I agree with Kite...your plants won't be able to handle right away a 1000w at full strength after being under a T5, I would recommend using a 600mh for a week or two for a week in veg. So T5 for initial growth, 600mh for the rest of veg and then 1000w hps in flower.

Moving from a T5 to 1000w HPS is likely going to be tough because I doubt the plants can photosynthesize and respirate fast enough to utilize the light they're receiving...they can't metabolize fast enough because they don't have the root structure for absorption and xylem/phloem for nutrient transport . So like Kite said, move the light further away from the plants until they acclimate, though you're just wasting light. You would have been better off having a 600w MH in veg, at least in terms of not wasting energy/light.

If you imagine a plant being outside in it's natural environment, you will never match the quantity of light that the sun produces while you're growing indoors. But that doesn't mean that your plants can handle all the light you give them all of the time.

That's all the long answer.


Short answer...start at three foot, like Kite said, and move it closer and closer every few days. Maybe in increments of 3"? Basically just keep moving it closer and closer, always while using your hand to check heat. If the plants start to get stressed at any point, simply back the lights off a bit and see how they react.

Ya I have a digital ballast that has 50%,75%, and 100%. I also use a 6" cooled hood with a good fan pulling a lot of air. I'll just put it at 50% and 3' to start out with and go from there. Appreate all the answer. Huge help!

"If you imagine aplant being outside in it's natural environment, you will never match the quantity of light that the sun produces while you're growing indoors. But that doesn't mean that your plants can handle all the light you give them all of the time."

That's not really true though. A 1000 watt hps can triple the amount of light the sun produces depending on height,on average the sun only gives off 70,000 lux

The lower the light, the less spread you will have and higher temps at the plants.. I adjust my light accordingly to cover as much area as possible. I would say 36" is a height that works well for most plants, without a noticeable difference in quality, that is if you use good bulbs.

For whatever it is worth, and maybe I just didn't read right.. BUT.. you can avoid a LOT of stretch by keeping your T-5 going until you see actual flower development (stretch is over) and THEN switch to HPS and watch them go BAM..

Your T5 will keep stretch to a minimum (get it as close as it can be) whereas HPS encourages a bit of stretch..

Again, whatever that is worth, I may of missed the mark on your question by trying to answer what I think it is you are really asking.. ..

333 maxwell kinda thought you have to interface HPS for the flower to begin. I've her of T5's with HPS for full spectrum but not just T5. Maybe I miss understood.

You don't need an hps to flower. A mh or similar cfl/t5's will help prevent stretch. You can flower all the way with em too with good results

Assuming it has to have bloom bulbs in my T5 though.

No, as QUiz said, you can flower under the Veg spectrum (for lack of a better description).. the plant triggers flowering because of it's daylight cycle regardless of what light you use. If you managed to grow something under a flashlight, it would still flower if you put it;'s time at 12 12 or so.. BUT, the plant does tend to really dig the red spectrums for flowerings and the healing blue spectrums for veg. That said, I have flowered under MH and 6500k CFL both at times, with completely delightful results. What I lost if quantity was made up in some really nice crystally quality.