400wat mh

Hey guys, just wondering how many plants you can grow with a 400watt metal halide..

These are what my medical grow will be under, I have 5 of them with ballasts, and a 1k.. but its a mh too.. will these work alright for the flowering cycle? should I throw in a red or blue led to pump up the flowering period or will the big Hid do alright?

Also, whats the yield like for a low stress trained plant grown under a 400watt mh? I know it depends on the plant and what not but a rough estimate would be darned handy..

I think one 400watt light should be sufficient for 2-3 plants right? or should I keep it too one or two? I was thinking of growing some tomatoes or something while I'm stalling trying to find a client to test out the rooms.. Are there any plants that closely mimic the grow cycle and needs of a pot plant?

Thanks!

Depends on the size of the plants your looking to grow.


And no, MH isn't the best light for flowering. It will work sure, but you'll get better quality under High Pressure Sodium. (HPS) You want more red in flowering, I don't know the science behind it, so im just parroting what I've read.

MH is heavy to the blue side, I don't see any reason you couldn't run that 1k and about 2-300w of red LED spaced out around the plants for flower tho......

I'm probably wrong about that, so take it with a grain of salt since I don't actually know shit! :D

My Name is Canniwhatsis, I'm not a botanist but I play one on the internet! :hippy:


I run about 6-10 plants under my single 400w MH, and vege to about 2' tall before flowering under either 400 or 600w HPS (total 1000w flower)

All my plants are staggered in growth to try and maintain an even canopy and continuous harvest (every other week or so)



Good luck with your grow, sounds like you've got a lot of meds in your future! :thumbsup:

Sweet, thanks!

I've got another question that has me somewhat dumbfounded :) I use a few of the 400watt mh lights for killer shop lights, and one of the ones I use regularily has a bright white/blue light that fills the entire room, while the other.. which came from the same place and looks more or less the same shines a more yellow softer light.. Could this be a Hps?

All of my lights minus the 1k Mh are rescues from a highschool gym where they were replacing all of the basalts and bulbs with florescents.. so thought its possible, I don't see why some would be Hps while the rest are Mh...

maybe I'll pick up some of those screw in red led's to mount vertically with the big mh up top.

One more question while I'm already typing :P If I build a grow closet and construct it so that the ballast is outside of the enclosed and sealed room.. will that help cut down on heat? Or does the bulb emit most of it?

Thanks!!

Yes if possible keep the ballast out of the room,... my 400w ballast runs about 100*F while on,... so keeping that heat source out of the room is vital to controlling temps. Tho in all reality the bulb generates most of the heat, every little bit helps.


If your looking at running the rescued bulbs, they won't be the right spectrum. Shop/parking lot/ highbay lighting tends to be much higher kelvin rating (8500-10000k) than growing lights (6500k) The whiter light allows us to SEE more colors and details even tho the light is so diffused. But it's kinda junk for growing.

As for the one bulb with the softer spectrum, it's probably old. All HID lights have a limited life span and begin to change spectrum and loose "Par Watts" over time.

Go to the local Hydro store and buy NEW bulbs that are intended for growing, you'll be surprised how much of a difference there is. (Be prepared to drop $70+ per bulb! I'm running the Hortilux 400w MH,.... $130 for a single bulb! :eek: And well worth it! :rastasmoke: )

good call, To be honest I have no idea what bulbs are in the lights that aren't hanging in my shop.. My father used to use them to start vegetable seedlings and winter over some orange and lemon trees and they seemed to work well enough, so he may have bought new bulbs at the local hydro shop he used to haunt:)

Do you think tomatoes would be a good test crop? or should I try something else?

Thanks again for your help, The 1k is definitely a grow light though :)

Tomatoes tend to like the same conditions and ferts (Or so I've heard)

I've found that tomatoes vary slightly from MJ,... much the same way as different strains of MJ vary from eachother,... little more/less N,... little lighter/denser soil,.... little farther away/closer to the light, whatever.


If your goal is to grow MMJ, do some more reading, figure out your room and environmental controls, and don't waste time with a "Test" crop of a totally different plant.

Tomatoes will flower and fruit under any light cycle, it's about maturity, the amount of light, and the amount of nutrients they are receiving. Same goes for peppers. (which is my choice indoor crop, got some ghost pepper seeds on the way! :D )

I digress :glugglug:, but you get the point.



Read, Read, Read, then Read some more...... Once you think your ready, your not, read some more, then start your grow.

I jumped in nuts first, and limped thru my first couple rounds because of it,... but I spent all that time reading up, now things are rolling nicely but I still read up since I have yet to have a "Perfect" bud roll out of my grow room. :pimp:

Right on, thanks again :)

The test crop would just be so I don't waste any seeds.. Where I live the power tends to kick it for a few days at a time during these few months. I would really hate to be in the final stages of flowering and have the lights go out and my plants freeze and die.. With tomatoes or something I could at least find out if my temp and humidity controls work, as well as whether or not those bulbs are the right ones :)

There is a killer grow shop here that I'll stop by once I have some money for a brain for my lights/ temp controls and stuff :)

Thanks!