slow growth and brown leaves!

[ganjawarrior]

i have some plants that i have just put into flower but in the last couple of weeks when they were still in veg 3 or 4 plants slowed rite down in growth and now quite alot of the fan leaves have gone nearly completley brown and curling up. The leaves are very dry and crisp to touch and they drop off very easily. By what ive read it seems to me that they are low in phosphorus but i just want a second opinion and a solution to the problem if you can please. Also the stems on the leaves are red aswell.

Im not growing in a very good soil to be honest so it has hardly any nutrients but im using CANNA VEGA nutrients when i was in veg and now the CANNA FLORES now that im in flower. Is there anything i should be adding to this to up my phosphorus levels. Thanks.

 

[7greeneyes]

that could be anything from a nute deficiency to the plants being rootbound and eating itself so to speak.

got any piccs?

p.s. :welcome: to Marijuana Passion, friend.

 

[ganjawarrior]

no pics but the CANNA VEGA is NPK 3-1-4 and the CANNA FLORES which im using now is NPK 2-2-4 if that helps.Thanks

 

[Hushpuppy]

We need a little more info from you:

Are you in soil or different medium? If soil What kind?

how big are the plants? and how big are the pots?

How often and how much do you feed them?

What Kind of light are they under? how much?

How old are the plants?

Is the necrosis occuring all over the plants or just at the bottom third, middle, or top third of the plants?

 

[ganjawarrior]

yeah im in soil but only a cheap kind so it has no nutrients in it so when i first potted them up i used tap water for a couple of days then added CANNA VEGA gradually. The plants will be about 18 inches tall and are in 15 litre pots they are 5 weeks old now but were about 3 weeks old when the leaves first started turning like this. I feed them when they need it at the moment eod. They are under 2 600 watt lights. The leaves started going bad in the bottom third of the plant but there is the odd one in the middle. Thanks

 

[HemperFi]

I'm sorry you are having problems. In soil it is rarely a PH problem, and if you have been feeding your plants correctly it probably isn't a nutrient deficiency. I had this same problem last year, and nobody had an answer for me. I have thought about it a lot, and I think you have a ventilation problem. I'm having a problem this year. I believe because I have solved my ventilation problems. Are your plants getting enough 02 above the soil and enough C02 at the roots? I'm no expert, and you haven't described your ventilation set up, so this advice may be way wrong, but even if it is just too tight of soil, I think it could cause the necrosis you are describing. Does your soil drain well? Are you replenishing the 02 every three minutes or so? Just food for thought....


Peace

 

[HemperFi]

I meant to say "I'm NOT having a problem this year."

I'm sorry you are having problems. In soil it is rarely a PH problem, and if you have been feeding your plants correctly it probably isn't a nutrient deficiency. I had this same problem last year, and nobody had an answer for me. I have thought about it a lot, and I think you have a ventilation problem. I'm having a problem this year. I believe because I have solved my ventilation problems. Are your plants getting enough 02 above the soil and enough C02 at the roots? I'm no expert, and you haven't described your ventilation set up, so this advice may be way wrong, but even if it is just too tight of soil, I think it could cause the necrosis you are describing. Does your soil drain well? Are you replenishing the 02 every three minutes or so? Just food for thought....


Peace

 

[The Hemp Goddess]

What do you mean that you are only feeding your plants when they need it, how do you determining if they need to be fed? How much are you feeding them? IMO, you need to get your plants on a regular feeding schedule. I would also advise you to check your pH.

Can you post up some pics?

 

[ganjawarrior]

i have some pics! i have a 10" box fan working as an exhaust and a 6" inline fan bringing fresh air into my room. they are controlled by a fan controller so i can control the temperature in my room but the weather has got alot cooler so the fans are not working at maximum but they are on all the time.

 

[The Hemp Goddess]

i have some pics! i have a 10" box fan working as an exhaust and a 6" inline fan bringing fresh air into my room. they are controlled by a fan controller so i can control the temperature in my room but the weather has got alot cooler so the fans are not working at maximum but they are on all the time.

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A 10" box fan will not operate well as an exhaust fan. Box fans are means to move air around, not exhaust it. What type of inline fan do you have? This will probably work better as an exhaust fan.

How often have you been feeding the plants? How much? You need to check the pH.

 

[Hushpuppy]

I could be wrong but that looks and sounds like a phospherous deficiency. Given that you are in poor soil and your feeding is light and the nutes aren't very high in Phospherous. Buuut, given that you have been using tap water, that could be keeping the PH off far enough to keep the plants from taking in Phospherous.

THG has a good point though as allways, ventilation is critical for both cooling and for bringing in fresh CO2 replenished air. Any time you have an enclosed grow room, you need to have your exaust fan doing all the work of sucking out the air, and allow the intake air to be pulled in passively so that you maintain a "negative pressure" in your room. This will save on money of running an intake fan that isn't needed(unless it is having to be pulled from a long distance), and it allows you to better control odor (since LEO is allergic to flowering MJ)

Hey Hemper, you had it backwards buddy; the O2 goes in the soil for the roots, while the CO2 is for above ground to be breathed in by the leaves

 

[HemperFi]

lol. Like i said, I'm no expert, but I do know the roots need oxygen and the leaves need carbon dioxide Sorry for the misunderstanding.

Peace

 

[ganjawarrior]

Thanks i did think it was a phosphorus problem by what i read but im no expert so i fort i would get a second opinion. I will check my ph today and if it is wrong i will sort it. Is there any different nutes which are better than CANNA FLORES which i can use which are not so light on nutes or a different feed i can add to it?

So are you saying THG that i should swap my fans round and use the 6" fan as an exhaust and the 10" as an intake? I just always fort that you should use the bigger fans as exhaust fans thats all?

 

[The Hemp Goddess]

No. You should use the 6" fan for exhaust, have a passive intake and use the box fan to move air around as it is intended. A box fan is a very very poor exhaust fan. If your 6" fan is a duct booster fan, you are going to need a better exhaust fan. Even when it is cool, your plants need a continual supply of fresh air all the time the lights are on. How large is your space and what size and type of light are you using?

I do not believe that the ventilation issue is causing your problems, but it will impact your harvest. Get your plants on a regular feeding schedule and make sure that your pH is correct. Unless you know that your pH is correct, nothing else you do will matter. A nutrient deficiency could definitely be due to nute lock-out rather than a lack of the specific nutrient.

 

[ganjawarrior]

okay i have checked my ph and it was a bit high about 7.0 so ive sorted and got it down to 6.5,6.6. The last couple of days no more leaves have gone brown so with a bit of luck i might of sorted it so lets wait and see.

THG ive done what you said with the fans but instead of using the box fan to move the air around i am using an osilatting fan it should do the same job i think. Thanks for the help i will let you know how i get on.

 

[ganjawarrior]

i sound like a fool but i forgot to check it i will do tomorrow. If the run off is high shall i flush out with PHed water no nutes?