Growing 2-3 plants under 400w HPS ONLY

Hi there, I didn't want to start a thread but after a fair amount of searching I couldn't find what I was looking for.

I am interested in growing 1-3 plants under one 400w HPS.

I have a lot of space, could use old fridges, cupboards or make a box. What would be the ideal dimensions for 1-3 plants?

If possible I would like to get away with growing some plants with only one light and nothing else that uses electricity.

I figure 3 months of using a 400w HPS will cost me $50-100 in electricity.

If I produce a 1/4 of an ounce of decent bud the electricty for the grow will be covered.

If I produce 3/4 of an ounce both the 400w HPS kit and the electricity will be covered.

I plan to buy some good potting mix for my vegetables and herbs so I wont include that into my grow budget.

Ideally I would like each grow to last around 3 months and yield 3 ounces, which would give me a quarter of weed per week to smoke.

As this will be my first grow I would like to know if my aim is achievable.

Anyone else grown solely with a 400w HPS and nothing else?

Any advice would be much appreciated.

Thank you all for the great information.

oh man 400 watt is plenty shoot for atleast 0.5 grams per watt so that would be 200 grams using a 400watt hps


so thats more like 6.5 ozs you will get easy


ive achived 1 gram per watt before too so 0.5 grams per want easy to achieve


i would recommend you do DWC insead of soil,


its so easy and grows way faster than soil





use these nutes trust me:

Big P said:

oh man 400 watt is plenty shoot for atleast 0.5 grams per watt so that would be 200 grams using a 400watt hps


so thats more like 6.5 ozs you will get easy


ive achived 1 gram per watt before too so 0.5 grams per want easy to achieve


i would recommend you do DWC insead of soil,


its so easy and grows way faster than soil





use these nutes trust me:

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Well I won't have any expectations to harvest that much. I would still prefer to grow more organically than use chemicals. I figure you are what you eat and the same goes for plants. Am I wrong? And are you trying to sell me something man

whosrolling said:

Well I won't have any expectations to harvest that much. I would still prefer to grow more organically than use chemicals. I figure you are what you eat and the same goes for plants. Am I wrong? And are you trying to sell me something man

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naw man but yea those arnt organic, i feel ya on the organic im just greedy goin for highest yields so ive always used that kind

anyway good luck

A 400w is definately sufficient for 3 plants, you could do up to 9 under it, at a decent size even. Figure it has a 3x3 footprint, that's pretty much the space you have, to work with. You will need fans, though - that light will put out heat. The smaller the space you put it in, the more heat will be an issue. Your aim is very achievable. Flowering takes from 7-12 weeks, depending on the strain you grow. An Indica dominant strain, will usually finish in 8-9 weeks. So - best bet is to pick one of those, veg for 4 weeks, then flower. Lastly - don't forget, they're gonna smell. Not just a little either. So you may want something for that.

I use chemical nutes, so I can't help you there. Check in with the Organics section - those folks can help you out.

I really want to do DWC for my second grow.

Hmm, thanks for the help. I'm just trying to think what to use as a room or space.

Are you talkng metres or feet?

Would it be alright to grow in a space larger than 3x3? I'm guessing if the space was enclosed the plants would grow better as the light can't escape.

I was initially thinking about getting 50-90w led lights but now have somewhat of an understanding I won't be able to harvest what I smoke (3,4,5 ounces in 3-4 months).

I just don't want to buy the shit anymore - I'm poor, enjoy gardening and don't really agree with not being able to grow your own weed. Wouldn't it stop a lot of people buying drugs of drug dealers?

DoeEyed said:

A 400w is definately sufficient for 3 plants, you could do up to 9 under it, at a decent size even. Figure it has a 3x3 footprint, that's pretty much the space you have, to work with. You will need fans, though - that light will put out heat. The smaller the space you put it in, the more heat will be an issue. Your aim is very achievable. Flowering takes from 7-12 weeks, depending on the strain you grow. An Indica dominant strain, will usually finish in 8-9 weeks. So - best bet is to pick one of those, veg for 4 weeks, then flower. Lastly - don't forget, they're gonna smell. Not just a little either. So you may want something for that.

I use chemical nutes, so I can't help you there. Check in with the Organics section - those folks can help you out.

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DWC is sweet but if you are new just go with soil. Dont over anylize stuff though. Its just a plant after all. It is no harder to grow that mums really. Most of what you read about plants dying and growing being so hard is 99% user error. If you are happy with 3/4 oz. then just keep it basic and you will blow 3/4 away guaranteed. Remember to provide light, water and occasional food and you will grow nice plants.

Actually, if I only wanted to grow like 3 plants maybe a lower wattage HPS would be an option no?

Another thing I didn't mention is that I want to end up with 3 females so maybe start 6 until they show sex.

No dont change your light. Guys will hit 1 plant with 1000 watts to get ready for the HTCC.

bigv1976 said:

DWC is sweet but if you are new just go with soil. Dont over anylize stuff though. Its just a plant after all. It is no harder to grow that mums really. Most of what you read about plants dying and growing being so hard is 99% user error. If you are happy with 3/4 oz. then just keep it basic and you will blow 3/4 away guaranteed. Remember to provide light, water and occasional food and you will grow nice plants.

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I agree, it is very simple but there seems to be lots of tweaks to improve a crop.

I want my first setup to be simple and practical for me.

I want to eliminate the need to buy and would like to smoke around a 1/4 oz per week. I want my stash to last until the following crop is ready.

That's my goal!

It almost makes my balls tingle imagining this dream becoming reality.

Tweaks are what kills plants man I am telling you straight. You want a head stash. Tweaks are for experienced guys trying to produce a cash crop. Check out this thread to see my current plants grown with no tweaks just TLC. https://www.rollitup.org/general-marijuana-growing/319782-northeast-growers-thread-show-em.html

bigv1976 said:

No dont change your light. Guys will hit 1 plant with 1000 watts to get ready for the HTCC.

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I guess if I wanted to acheive my 3-5 oz harvest I shouldn't lower my chances.

If I got a 200w HPS I would only save about 30 or 40 bucks on electricity.

Thats not even 3 grams on the market for me.

Thats right. My 11 year old could yeild 3 oz. so like I keep stressing just love your plants and they will love you back in about 4 months.

yes sir. if you veg for 2 months and flower for 2 or a lil more months. You wanna produce an ounce a month for personal use. Thats 4 ounces out of a 400 watt which is what i think youll get if not more. Just remember that simplicity and consistency is what makes this work. You can't cheat time and trust me your plants will definitely not comply if you try loading it with all the nutes you got or water it all day long. then again, growing from seed to finish will teach you ALOT. you will get a feel for the plants.

I'd go with 4 plants if i were you, as it will allow you to arrange your plants in a square pattern under the light, and waste as little as possible. Why go with 3 plants and leave an open spot, when you could go with 4, and yield another ounce or two, right? You should also go with the same strain for all of them. That'll keep the nute requirements the same for each, and will make it easier to keep your canopy as even as possible.(important for good yield under that light)

Check out my journal, I am using a 400 watt HPS and I'm doing a scrog style grow. I'll get about 1/4 pound off of one plant and it not tall at all ! this is the link! https://www.rollitup.org/grow-journals/303844-aurora-indica-scrog-screen-green.html

I keep 4 under a 400w hps. I did a 12/12 from seed grow recently under that light but I'm really sold on using 5000k cfl bulbs for veg. 4 26w bulbs a couple "y" sockets and 2 old lamps gives you plenty of light for a 2'x2' area. When my 4 get too big for the "box" I take them to the 400w hps which hangs in a 12x10 room. I grow soil. I'm pretty new. I took 4.75 oz of my last plant. One thing, I used to use schultz nutes because they were easy to get. I tracked down Fox Farms and my yields doulbled. (from about 2 oz per plant). I expect to pull 6-8 oz per plant on my current grow... You just get the hang of it. You really do need a fan and people aren't kidding about the smell.

WolfScott said:

Check out my journal, I am using a 400 watt HPS and I'm doing a scrog style grow. I'll get about 1/4 pound off of one plant and it not tall at all ! this is the link! https://www.rollitup.org/grow-journals/303844-aurora-indica-scrog-screen-green.html

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I like it man! I'm sure I could go to the hardware store and get some mesh.

jawbrodt said:

I'd go with 4 plants if i were you, as it will allow you to arrange your plants in a square pattern under the light, and waste as little as possible. Why go with 3 plants and leave an open spot, when you could go with 4, and yield another ounce or two, right? You should also go with the same strain for all of them. That'll keep the nute requirements the same for each, and will make it easier to keep your canopy as even as possible.(important for good yield under that light)

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Thanks for the info and advice.

I wish I could pick my strain but I will be getting whatever seeds I can get. I can't order them here as far as I know. Don't want no pests on my trail.