6500k 4' T5 HO flourescent for Autos?

Just received my mix pack of autos (NL, AH, BB) and am getting ready to start my first grow. I need some advice on lighting. I have a VIVOSUN 6500K 4’ T5 HO fluorescent and wanted to know at what stage this light would be beneficial. Also, what distances from light to plant, and also hrs? It’ll be indoors in my garage, plenty of room and air movement. I live in southern California and have decent weather, so outdoors is an option? Just excited and wanted to get some advice,


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Hey, @rikcote, welcome to ILGM! That fixture should do really well for seedlings, and through at least part of the veg stage, since 6500K will lean more toward the blue end of the spectrum. It won’t give you the greatest penetration once the plants start getting a little taller, but the color temperature should keep them squatty to begin with. You can raise it away from them at the loss of some penetration and intensity, if you need them to stretch a little for training or anything like that. But you should be able to start with them right down on the seedlings, within 6-8" or so once they’ve sprouted.

You may have pests to deal with outdoors. You have more control over pests as well as the environment indoors. Timing is key, but if the weather is right, as long as there’s no frost, it might not matter so much. I’ve never grown cannabis outdoors, but if that’s an option, sun is free! My outdoor inexperience stated, I’d start them indoors under your T5 fixture, in either the big solo cups, or pots about 1 quart/liter or so. Then when they’re established and ready to pot up, I’d transplant them right out into the ground, amended of course, or into some 7 or 10 gallon cloth pots. But you’d be watering more often with the cloth pots. I’ve also never grown autos. @blackthumbbetty and @HornHead both grow autos and can probably add better advice for them. I just know that outdoors in the sun, with room for roots to spread out, you’d have a much larger yield than indoors.

Excitement is good, but make sure you do your research and make good investments the first time. There are tons of experienced, knowledgeable growers on here, and there’s no such thing as a dumb question. :+1:


Thank you so much! I love this company/website, and especially the people involved. What type of light would be needed for flowering? And, what ratio of light vs dark?

Thanks again!!!

You’ll want a 3500k light for flowering, but we can’t recommend a specific light until we know the size of the area you want to light. Do you plan on using a tent or enclosing a small space within your garage for growing?

For autos, start at 24/0 for a week, then go to either 20/4 or 18/6 til bloom begins. Once blooming, go ahead and save yourself some money and flip the lights to 12/12; this is not necessary for autos, like it is with photoperiod plants, but if you can save a few bucks, here and there, why not?


Thank you so much for that info, I’ll take all the advice I can!!!