Blurple or pure white for seedlings?

Hello,

First post over here, have been reading for a long time about cobs and led in general. Have build a few cob lights and getting great results. This question however is about seedlings.

I'm planning to build a grow tent with multiple layers of seedlings on rockwool cubes. I know white light rocks but with seedlings I'm not sure what to choose...

I have found a led bar with 1w leds to place directly above the seedlings. Is it best to have white light or a R & B combination? If so, what ratio or kelvin temperature is best for seedlings?

Thanks alot

depends on what your germinating them for

I know for flower red/blue @ 3/1 or 5/1 is about where you want it, so I`d go with cool white leds or 2/1 red/blue or 1/1 maybe even 1/2 or 1/3 depends on how much space and budget I had

More blue in veg normally gets you more females but sometimes a warmer mix of light can speed up your veg times and help make the stems thicker even if it makes them a bit longer

Also most people seem to forget a bit of some of the uv bands can help keep mold away

I will be germinating fem seeds, so no worries about female %. This tent is only intented to grow seedlings. The lights will be on 18/6 all the time for about 1.5/2 weeks; ready to go into bigger flowering room. I want them to grow as quick as possible, and nice thick stems are part of that.

3000k-5000k white leds all do fine in veg and are very efficient. Adding red leds to your veg lamp will theoretically help keep the plants shorter and with a higher %Pfr, but red leds have a lower efficiency than the white cobs everyone here is using, and it's uncertain whether the effects from red are worth it.

churchhaze said:

3000k-5000k white leds all do fine in veg and are very efficient. Adding red leds to your veg lamp will theoretically help keep the plants shorter and with a higher %Pfr, but red leds have a lower efficiency than the white cobs everyone here is using, and it's uncertain whether the effects from red are worth it.

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Whenever I grow with heavier red\deep red balance my plants stretch more. I did that once with a heavy thai influenced golden tiger and I got 6" + internodes. Its true about the effects of far red vs red\deep red on stretch, but who uses far red in a veg light for seedlings ?

5K to 65K is my preferred range for seedlings. generally more efficient, cheaper to build and the extra blue keeps them nice and compact.

PurpleBuz said:

Whenever I grow with heavier red\deep red balance my plants stretch more. I did that once with a heavy thai influenced golden tiger and I got 6" + internodes. Its true about the effects of far red vs red\deep red on stretch, but who uses far red in a veg light for seedlings ?

5K to 65K is my preferred range for seedlings. generally more efficient, cheaper to build and the extra blue keeps them nice and compact.

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Are you talking using a warmer color temperature, or using 630nm-660nm and seeing more stretch? There's a big difference between adding red and a using a lower color temperature. Using more phosphor will convert more blue into a medium band centered around amber, which lowers the color temperature, but amber causes %Pfr to be significantly lower than red.

churchhaze said:

Are you talking using a warmer color temperature, or using 630nm-660nm and seeing more stretch? There's a big difference between adding red and a using a lower color temperature. Using more phosphor will convert more blue into a medium band centered around amber, which lowers the color temperature, but amber causes %Pfr to be significantly lower than red.

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significantly warmer color temp using reds > 600nm but no far reds. I found this with monos with lights really heavy in reds.

If there isn't any significant far red in the spectrum, Pfr\Pr isn't really a factor. The stretch effect is from Pr\Pfr is really a far red effect since in deep shade far red overbalances the reds, which signals the plant to stretch so it can go into the light.

generally if you use more phosphors color temp drops, also generally if you use more phosphors in the deep red range color temps drop.
if I add more deep red monos to supplement a light color temp drops, so no not really any difference.

PurpleBuz said:

generally if you use more phosphors color temp drops, also generally if you use more phosphors in the deep red range color temps drop.
if I add more deep red monos to supplement a light color temp drops, so no not really any difference.

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Color temperature means nothing to plants. It's SPD that matters and the resulting SPD from adding reds is different than from adding more phosphor.

churchhaze said:

Color temperature means nothing to plants. It's SPD that matters and the resulting SPD from adding reds is different than from adding more phosphor.

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so what ?

to say color temp means nothing to plants is a useless distraction. of course the details of a spectrum that result in a given color temp are significant. But if I take a given spectrum of say a 3K white phosphor cree cob and I supplement with deep red monos, the color temperature will drop and the stretch will increase and the spectrum will also show a bigger peak in deep reds.

churchhaze said:

Color temperature means nothing to plants. It's SPD that matters and the resulting SPD from adding reds is different than from adding more phosphor.

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Sick name. Man I miss that church insence Haze