I’m a beginner and haven’t received my seeds as of yet but I am going to order my lights and was wondering since I’ll be growing them inside, should I use the hps 600 watt lights for the entire process or is that not the right move? I did not want to have to switch lights, for example, purchase the CFL light and the HPS but it seems as tho during the vegetation stages it needs the CFL and not the HPS. Please advise I would like to be well prepared 
Fluorescent light is normally used during veg because veg doesn’t need as much intensity as flowering does, and it could depend on numerous factors as to why you might choose a fluorescent light over a HID light, but none of them are specifically because the vegetative cycle requires this light over the other. In general you need light with more blue in it for veg and more red in it for flower.
6500k is slightly blue shifted, 5000K to 5800k is considered kinda right in the middle, very balanced, and 2700k is red shifted. Those are some of the most common numbers, I’ve seen 3000 and 3500k as well. Pretty much anything above 5000k to 5800k is blue shifted spectrum light and below is red shifted. Yes, in flower, using fluorescents, in general more 6500Ks are used in veg and more 2700Ks are used during bloom/flower.
Chlorophyll absorption peaks are 430 nm and 662 nm for chlorophyll a, and 453 nm and 642 nm for chlorophyll b. Chlorophyll b is not as abundant as chlorophyll a, and merely help in increasing the absorption range.
No matter the type of light, if you can find the exact specs for its lumens/FLUX per square foot (or the equivalent PAR for red/blue only LEDs) you can use this as a loose guide as to what you need as minimums:
Seedlings and clones require about 400-1000 lumens per square foot.
Vegetative growth requires about a minimum of 2,000 to 3,000 lumens per square foot.
Flowering requires about 5,000 to 10,000 lumens per square foot, ideally, and can take possibly much more.
10,000 lumens is supposed to be about the average power of the sun at sea level on a clear day at high noon, or something like that, lol. 8,000 - 12,000 lumens is supposed to be about the average power of the full sun without any overcast or no clouds depending on altitude and potentially other factors.
It’s not ideal, but you can make do with 2,000 lumens for an entire grow if necessary.
If you need aggressive vegetative growth, HPS does have enough blue light in it to keep the plant happy and healthy and the intensity to likely keep the plant from stretching very much, but if you want even less stretch but almost as intense of light for aggressive growth, it would be better to get a metal halide HID bulb that would work with your fixture, as a 600 watt MH would have more blue in it and better overall balanced spectrum for vegetating plants aggressively.
If you have more of a perpetual grow setup where a slow veg occurs in the veg room until they are ready to flower while a plant is finishing up flowering in the flower room, then fluorescent light might be more applicable and maybe more affordable for that style of grow, in the end it depends on how you plan to grow. If you are going to grow from seed to harvest in one room then the one HPS light could work just fine, you will just have to keep it very high away or run it at reduced power for small seedlings and increase the intensity slowly. Seedlings and small plants can take a lot higher intensity than the above stated minimums, just be careful.
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Hey, thanks for the info! I guess since this is my first stab at it, I’ll take the easy route and purchase the blue light for the vegatative stafe but I will also look into purchasing the hps light for the flowering stage. So when my 18/6 hr process is complete I’ll start the 12/12 hr process with the proper red light. I appreciate your help. Once I start my process, I will update whenever I may need further assistance
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I would buy a small T5, instead of buying CFLs, especially if you want to use a 600 hps for bloom. Here is a link to one I bought 3-4 months ago. Great price, and you can buy hydrofarm grow bulbs when you need to replace the originals.
Link for T5
2 foot 4 bulb T5 for Veg
I also bought this last year. Great price and versatility. I bought the 400 watt for my 4;x4; tent. I use it at the 200 watt setting MH for veg, and increase to 400 watt HPS for flower.
Link for digital HPS/MH lamp
IPower digital HPS/MH light system
Both these lamp systems are nice quality, and inexpensive. You can shop around for a little bit better deal, but I think you will be happy with these at a minimal investment. Good Luck, and Happy growing. Peace
Thanks latewood! I came across the 2nd link on amazon yesterday and it was around the same price that is the one I was planning on investing in. As for the T5, it looks like a good buy for the vegging I might invest in that one as well so that I can guarentee good results. I appreciate these links, I’m going to make these purchases asap!!
Good for you. I am thinking of trying to get those products in my hygro store. I think I have sold many for “them” LOL Peace
Haha, in that case, you definately should! I’m excited and can’t wait to give it a try. I’ll update you on my process as time progresses! Once again, thanks for the links!
Is there a reason not to use the mh for veg state?
Also, what happens if after seedling stage, one goes directly into 12 on 12 off? If it’s cool to do that, which light for that?
Thanks guys,
Drew
I always use MH in Veg. HPS in Flower. This is one reason the Ipower digital is so great. It comes with both lamps, and all you do is change the lamp (bulb) at transition to flower. 
Some growers have got away from MH in Veg due to the development of Enhanced spectrum bulbs. This means that if you buyan “EYE Hortilux” HPS bulb, it comes with an enhanced blue spectrum for veg.
Either way works; IN fact, I still find older expert growers that use the EYE Hortilux MH with Red spectrum enhancement for the entire grow .
IN some cases people take shortcuts; Others have a limited budget. IN the end; Try to get something worth having for a long time.
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I too am a new beginner. And my question is how many lamps would you recommend for for a 4x4x10 tent. Im gonna go with the MH/HPS combo link you provided. But im gonna go with the 600 watt version. I only need 1 of each bulb for space provided?
Correct, one bulb of each, 1 MH for veg and 1 HPS for flower, and 600 watts should be plenty, especially with HPS.
Question can I use led thru entire grow process
It might be able to be used the entire grow process, plants need more or less light depending on what stage of growth they are in. Most people use a lower powered light for seedlings, and then pull out the bigger lights for veg and flower.
And so, no matter the type of light, if you can find the exact specs for its lumens/FLUX per square foot (or the equivalent PAR) you can use this as a loose guide as to what you need as minimums:
Lumens(or equivalent PAR) per square foot:
Seedlings and clones require about 400-1000 lumens per square foot.
Vegetative growth requires about a minimum of 2,000 to 3,000 lumens per square foot.
Flowering requires about 5,000 to 10,000 lumens per square foot, ideally, and can take possibly much more.
10,000 lumens is about the average power of the sun at sea level on a clear day at high noon. 8,000 - 12,000 lumens is supposed to be about the average power of the full sun without any overcast or no clouds depending on altitude and potentially other factors.
It’s not ideal, but you can make do with 2,000 lumens for an entire grow if necessary.
Ok still learning using regular seeds before using my kush I brought from Ilgm and investing more money. …thks
Keep in mind your elec bill. I just got my first bill after switching from cfls to 400watt MH on 18/6 and it made my bill jump about $40. I’m thinking of cutting my veg time by a week or two just so I can switch to 12/12 and hopefully cut back $20 or so a month. A $40 increase isn’t all that much more, however when my bill jumps from $79 to $120 it kinda looks bad. o.O
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I agree that’s my concern elec bill since start growing I find myself cutting as much things in house ie home theater system pc if not using
It’s tough. Especially since summer is upon us and my house has been using the air conditioner more as well. But that shouldn’t increase the bill that much not nearly as my lights and fans running almost 24 hrs a day do.
It sometimes takes a while to remember things you forget.
MacG’s reply switched on an old reference. When you are talking about 20,000-30,000 lumens; You have to equate the distance from the lamp tot he plant canopy and beyond.
lumens at the lamp will be rated much higher thanthe lumens available at the plant canopy.
Next we have to evaluate light penetration.
Need more light tent is 32"x 32"x 64 don’t really want to use hps 250 watt or 400 so I don’t have to deal with heat and more cost thinking about getting Apollo cfl 250 watts my question is they have three different bulb types 2100k=9750 lumens 2700k=11,050 lumens,6400k=10,850 lumens I know more lumens is what’s most important but it seems like 6400k is mostly used what is the best one to get…pls help expert advice needed
That VFL will be great for a small tent! Glad you introduced that picture and idea to our community. Most folks do not want to spend the extra bucks for this size CFL…, Thanks
I would definitely use this in that smaller sized tent.