Which hid light?

i have 6 young seedlings, 3 weeks old, i have them under a 125 cfl, i want to change the lighting to hid, i have a 250mh, 400hps and a 600hps. i was thinking the 250mh would be better than the 400hps for vegging , would this be true? If you were to change the lighting, which light would you choose, and why?

250 watt...less heat in ur grow space/ and you could veg the seedlings for a while before u wanna change to the 400 watt..

thank you very much for helping me. another couple of questions. how high should i keep the 250mh light bulb from the top of the seedlings? and will i only use it for a couple of weeks and then introduce the 400hps? i will use the 600hps for flowering.

andy7000 said:

thank you very much for helping me. another couple of questions. how high should i keep the 250mh light bulb from the top of the seedlings? and will i only use it for a couple of weeks and then introduce the 400hps? i will use the 600hps for flowering.

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depends on the bulbs, but why not use the 600hps if you have the space? Veg or not, 600hps is going to outperform a 250mh any day.

Inneedofbuds said:

depends on the bulbs, but why not use the 600hps if you have the space? Veg or not, 600hps is going to outperform a 250mh any day.

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would a 600w not be a bit extreme for 3 week old seedlings? if i did us the 600w would i not have to have it raised very high from the tops? i thought metal halide would be better for young seedlings, no?

i used aa 600 1st day seedlings'

andy7000 said:

would a 600w not be a bit extreme for 3 week old seedlings? if i did us the 600w would i not have to have it raised very high from the tops? i thought metal halide would be better for young seedlings, no?

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MH generally provides more blue light than HPS and blue light is used more by a plant during vegitation, but that doesnt mean that 250 of pure blue is better than 600 of orange/red. You can't have too much light for a plant, only too much heat. If you have proper ventilation, use the 600.

I'm with INOB. Use the 600. If introduced with a rather long spacing (1m or so) for several days before lowering it to optimal spacing, everything will be fine. A cooltube is a very good thing to have on your 600.

While MH is generally preferred for vegging, it depends how you're going to use the plant you're growing.

I veg my mums with a 400HPS. I run a SoG op and prefer very tall clones.



HPS in vegging causes some elongation of the stems, so this suits me.

If I were vegging plants that I would later flower, I would use MH as it makes a more compact plant with shorter internodal lengths.

It's great to have such a library of lighting, though!