T5 HO compact fluorescent, closet grow

Hey there. I'm growing 10 plants in a 2' by 3' closet under (2) two foot T55 HO Lamps. There are 2 bulbs in each lamp, so that's a total of 4 bulbs @ 5,000 lumens per bulb, for a grand total of 20,000 lumens. (according to the advertised output)

Current light schedule is 18/6. Temps range from 65-78 F with humidity @30-35%

Plants are doing ok, but not great. Found out PH was at 8 or more for 45 days. Now feeding with 6.5 water, with 1/2 teaspoon epsom salt per gal. and Foxfarm Grow Big @ 1/2 strength.

3 Plants are now 55 days old. The rest are about 40 days old. I keep them all on the same light schedule.

Started with one light, but soon realized i needed at least one more.
Plants were doing pretty good at first.
Then they stopped growing and some got light green all over.
Others got light green lower leaves and tops.
Major 'claw' and folding under on one plant.



Hoping things get better soon. Would appreciate any advice on how to improve before I switch to flower.

Fluorescent, closets and soil aren't really my area of expertise but I'll start until someone better served shows up.

Definitely looks like severe nute lockout from a wack ph, needing more nitrogen is definitely evident with the light green going yellow. After you've watered have you tested the ph of the runoff? You may need to adjust it further. Also might say because off the heavy looking droopy leaves that you may be overwatering as well. When you flip to 12/12 the plants are gonna about double in size so that closet is gonna get real small real quick. Probably want to scale back on plant number when you do flip. The humidity could be a little higher. Can't comment on the lights really but it looks like you can fit another in there. Good luck man, I'll be around.

neosapien said:

Fluorescent, closets and soil aren't really my area of expertise but I'll start until someone better served shows up.

Definitely looks like severe nute lockout from a wack ph, needing more nitrogen is definitely evident with the light green going yellow. After you've watered have you tested the ph of the runoff? You may need to adjust it further. Also might say because off the heavy looking droopy leaves that you may be overwatering as well. When you flip to 12/12 the plants are gonna about double in size so that closet is gonna get real small real quick. Probably want to scale back on plant number when you do flip. The humidity could be a little higher. Can't comment on the lights really but it looks like you can fit another in there. Good luck man, I'll be around.

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I am actually planning to check the runoff PH tonight. I'm due for a good soaking. I know it looks like overwatering, but I don't think that's the case. I wait until the pot is quite light, and soil feels dry about 2" down as well as at the drain holes. In fact, I waited an extra day after I thought I should water, and the next morning leaves were super droopy and dessicated looking.

I know there's not enough room in there for what i've got growing. I'm planning on thinning them out just as soon as i know which are female. Do the girls usually show up first? So far, three have grown pistils, and still no males are showing up. Planning to pick out the two best girls and give away any others to a friend.

Salt buildup, flush with 3-4 times the amount of pot size with plain water then feed half strength nutes.

^su said:

Salt buildup, flush with 3-4 times the amount of pot size with plain water then feed half strength nutes.

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Does a high PH cause salt buildup? Just wondering how you know that's what it is.
Also...Can I flush with tap water or does it need to be PH'ed, RO etc?

Salt build up is the end result of nutrient lock up/out. The plant absorbs the nutrients (salts) best at a pH between 5.5-6.5. Anywhere out of that range the plant will stop absorbing and the salt based nutrients will begin to build up.

neosapien said:

Salt build up is the end result of nutrient lock up/out. The plant absorbs the nutrients (salts) best at a pH between 5.5-6.5. Anywhere out of that range the plant will stop absorbing and the salt based nutrients will begin to build up.

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So adding epsom salts or cal/mag would be detrimental then, right?

bamboofarmer said:

So adding epsom salts or cal/mag would be detrimental then, right?

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If you don't get the pH right then it would just add to the build up. Pour some water in and check the pH of the runoff. You probably will need to do what ^su said and flush the soil out. As far as your question about what water to use that is a still a debate amongst most growers. I fill 5g buckets up with my tap water and let them sit a day or so to get rid of the chlorine and whatnot. As I don't use soil I can't comment correctly on whether it should be ph'd for flushing purposes but I imagine it wouldn't hurt.

Thanks for the suggestions Neosapien. I did those runoff tests on my 3 biggest plants. Here are the results:
PH of straight tap water over 8 PH of tap after adjusting 7ish?

Plant #1 49 days into veg PH of runoff after 1/2 gallon 4.7? PH of runoff after 1 gallon 7.0?
Plant #2 38 days into veg PH of runoff after 1/2 gallon 5.5?
Plant #3 49 days into veg PH of runoff after 1/2 gallon 4.5?

I know I should get a digital tester, but I figure this is good enough for the girls I go with. Haha!

I'm going to bump this and hope someone with more soil knowledge can I chime in. I've only ever ran hydro setups and don't want to give you the wrong advice. But in the meantime I would guess the results of the lower ph with the first half gallon contained alot of the built up fertilizer salts and the latter half with the higher ph was sans salts. If it were me I'd wait til the next feeding and pour 1/2 strength nutes ph'd to 6.5 and test the runoff from that. Then I would compare that test and the previous test to guage how I was ph wise. I know they make soil ph meters but have never used them and as such can't comment on their effectiveness. Like I said I'm no expert and sometimes good gardening is had by experimenting.

A few things, "The lumen (symbol: lm) is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source"

So don't measure by lumen's, only wattage. And wattage per sq foot should be 60 Watts, a low number. Which you are more then good with with those lights. BTW I have the same light but mixed the red and blue bulbs. Grow is in sig if you want to check it out, I just started. It seem's you are using your tap water? Mine has a high PH (8+) with NO chlorine and hard water. So what I do is add some white distilled vinegar (roughly 2 teaspoons per gallon) and the water PH drops to ~6.5. I do that for plain watering and when mixing nutes I add my nutes THEN check the ph and adjust it for around 6.8 as that ph will deliver ALL your nutes to the plant.

Also, it might be good to flush every 4 weeks to rid of salt build up to prevent any headaches. just a tip I though might help you as the yellowing looks to be like the PH is off and nutes are getting locked out. Also looks to be lacking in nitrogen as yellowing from the bottom up suggest this is the problem. Otherwise, keep it up they look great! Got me excited for my grow since I busted out my old HTG pl-55 that I never used and got it back on '08

bamboofarmer said:

Does a high PH cause salt buildup? Just wondering how you know that's what it is.
Also...Can I flush with tap water or does it need to be PH'ed, RO etc?

Click to expand...

you can flush with tap water, just adjust the PH. Rain water is better but if tap is all you got then adjust the PH

looks like a deAD thread.

BSD0621 said:

A few things, "The lumen (symbol: lm) is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source"

So don't measure by lumen's, only wattage. And wattage per sq foot should be 60 Watts, a low number. Which you are more then good with with those lights. BTW I have the same light but mixed the red and blue bulbs. Grow is in sig if you want to check it out, I just started. It seem's you are using your tap water? Mine has a high PH (8+) with NO chlorine and hard water. So what I do is add some white distilled vinegar (roughly 2 teaspoons per gallon) and the water PH drops to ~6.5. I do that for plain watering and when mixing nutes I add my nutes THEN check the ph and adjust it for around 6.8 as that ph will deliver ALL your nutes to the plant.

Also, it might be good to flush every 4 weeks to rid of salt build up to prevent any headaches. just a tip I though might help you as the yellowing looks to be like the PH is off and nutes are getting locked out. Also looks to be lacking in nitrogen as yellowing from the bottom up suggest this is the problem. Otherwise, keep it up they look great! Got me excited for my grow since I busted out my old HTG pl-55 that I never used and got it back on '08

Click to expand...

Thanks for the reply! Yeah, i'm using tap water, but I'm adjusting the ph now and things seem to be perking up a bit. Also had some rootbound plants which I transplanted. Right now I'm using just the veg bulbs, but I've got some bloom bulbs also, just waiting to mix 'em in when I flip the plants. (thinking i'll do 2 bloom and 2 veg) My first set of bulbs sure did get dim quick! Have you had that problem with the HTG's?

I'm actually thinking of flipping all of 'em to 12/12 this week. The young ones too. I'm expanding my little closet out a bit so I can fit my heater and another fan in there. So far, it looks like 4 are female, and still no males have shown up. I'm gonna have to give some away because I don't think I can grow more than two plants in that space and under those lights.

Do you think the plant with major 'claw' going on is worth keeping? Thanks again, and I'm gonna check out your grow right now. Peace.

Just wanted to update and say that after flushing all my plants with ph adjusted water and doing some transplants, all the plants made a huge improvement! I also added 8, 23 watt cfl's. I separated the males, but haven't been able to kill them just yet. 6 males 4 females.
These pics are with all 10 plants in 6' x 3' enclosure. Currently there are just the 4 female plants under the lights. Hope to add pics of those soon.

Yeah SUCH a huge improvement!! Keep it up! Also, I haven't noticed the bulbs getting dim quick. So it could be a separate issue?

Update: About a week or two into the 12/12 photo period now. Plants are getting big and bud sites are developing all over.


I'm wondering if I should trim some of the lower, spindly branches.

Update: About 18 days into 12/12 light schedule. Oldest plant is about 80 days old and 36" tall.
Youngest plant is about 65 days old and 24" tall. (measured from top of pot)

Currently using 450 watts for lighting. (10, 23 watt cfl's and 4, 55 watt T-55's)

Watering every other day or so with tap water that has sat out for 24 hours and adjusted to 6.5 ph.
Two feedings with nutrients added @ 1/2 to 1/3 strength, followed by one heavy watering with no nutes.
Nutrients: Fox Farm Big Bloom1/2 tsp per gallon.
Fox Farm Grow Big 1/2 tsp per gallon.
cal/mag plus 2 ml per gallon.


I do apologize for the quality of the pictures. My good camera broke some time back.

Update: about 32 days into 12/12 light schedule. Tallest plant is 42" from top of pot. Exactly two weeks ago, she measured 36", so only growing about 1/2" per day. I guess the growth spurt is over...Unless it is yet to begin...but I doubt it. Anyway, things are getting sticky, and fragrant.

Temps went way high a couple times last week. Highest temp was 84 for about 3 hours due to hot afternoon and no a/c. I need to do something to keep temps down. Was going to install a window air conditioner, but don't want to deplete my already too low humidity, and they are expensive too. Thought about just a window fan, but those let light in so I'm still not sure what to do.

I backed off on the 'grow big' and cal/mag plus for the last few waterings, but amped up the 'tiger bloom' to 1/2 recommended strength. Most of the leaves are looking dark green, so I figured I could go without Nitrogen for a bit. Next watering will have it back in at 1/2 strength, along with 1/3 strength cal/mag plus.

I also gave two foliar feedings a day apart with 1/3 strength cal/mag plus and tiger bloom. Sprayed the leaves down on undersides as well as I could just before lights out.
Changed the light setup again. I'm now using a 7' x 3' area for growing.
This plant is taller than my broom!
I'm hoping the cola gets a little fatter.

Had the plants in some natural light while rearranging light setup. They look much prettier with sunlight on them.
I mentioned to a friend a while back that I was thinking of trying to do a grow. He brought me this bag seed seedling a few days ago to get me started. LOL! I threw it in under the canopy. So there's the start of a 12/12 from seed plant right there mmhm.

guys calm down with telling this guy to flush his plant I think what he needs to do is properly PH his water, if your PH was at 8 I can tell you right now this is ph lockout. Don't flush your plant just water with water that's at a 5.8 PH .