Leaf Tips Dying - pH too high?

Hi, I am on my first grow and need some help diagnosing what is happening to my plant. I first noticed the problem about a week ago.

INFO
The plant is 3-4 weeks old (can't say 100% because I received this one as a seedling). I am watering every two days. I fed it a very diluted fert solution (N-P-K 24-8-16) a few days ago (because I thought maybe it had a deficiency). With no clear improvement, I measured my pH, which came in at about 7.5 (Last week it was at 7.0). The water I am using has a pH of 7.0. However, I am also using one of those non-electronic, probe pH meters, and although it seems to measure the pH of liquids great, it also seems to have a more difficult time with solids. I have a 65W CFL located about 8 inches away from the top of the plant, a 42W CFL about 5 inches away, and a 27W CFL about 5 inches away. Temperature is usually around 80, but sometimes jumps up to 85 in the night (when the heater is running throughout). I wish I could nudge the temperature down to 75ish, but that is going to be difficult to do. It is also on a 24-hr light cycle.

THE PROBLEM
The problem with the plants is that the leaf tips look like they are dying. Almost every leaf on the plant at least has a crispy-looking tip. Some, however, have extensive damage to the leaf edges (pictures attached). I originally thought older leaf sets were being targeted, but it seems to be random. However, new growth is not immediately affected (although it might look like an Iron def.). Some people who I have asked suggested nute burn, but I've barely given this plant anything! I should also add that most of the leaves exhibit a yellowish tint in between the veins and some, but not all, of the stem is reddish-purplish, which I think is another sign of deficiency.

MY GUESS
If anything, I would think it's a nute deficiency, either caused by a lack of feeding by me or a high pH blocking some nutrient uptake. But, this is my first grow so I am very uneducated on these things.

PIC GUIDE
1st Pic - lower leaf set
2nd Pic - mid leaf set
3rd Pic - Top-down view of plant

**All pictures taken morning of 2-12-10

I really need some help! Thanks in advance!!

Stop with the nutes wasnt ready yet i would say and try a 18/6 light cycle the plant needs time to grow and does so when its sleeping.

EDIT:you might want to repot that into a bigger pot three weeks the roots might not have any where to go in that small cup

To hot got burnt.Flush with water.Cut the dead tips off.Let the soil do it's job.No nutes for a while.This should help.oregon024

your seedlings are nute burnt. However, when testing your pH, make sure to test the runoff. Things like dolomite, can raise pH. grab a clean cup, and water your plant as usual(without nutes for a bit). With the clean cup, catch the runoff water that goes through the roots and soil. This is how I check my pH for soil. most pH meters, especially the ones made by hanna, are meant to test pH of a solution. The solution will still be cloudy, but it's better than testing soil. or get a soil specific pH tester (i think these are cheaper, but less accurate). I use a hanna, they are worth the money.

pH your water either up or down, depending on your reading. do some experimenting.

A cannabis plant enters the vegitative state of growth once it has developed it's first set of 7-pointed fan leaves. This is the best time to begin administering nutrients.

I don't know when a plant is generally considered to be old enough to safely flush, but a flush might be what you'll end up having to do.

Peace,
monkey

fendz457 said:

Hi, I am on my first grow and need some help diagnosing what is happening to my plant. I first noticed the problem about a week ago.

INFO
The plant is 3-4 weeks old (can't say 100% because I received this one as a seedling). I am watering every two days. I fed it a very diluted fert solution (N-P-K 24-8-16) a few days ago (because I thought maybe it had a deficiency). With no clear improvement, I measured my pH, which came in at about 7.5 (Last week it was at 7.0). The water I am using has a pH of 7.0. However, I am also using one of those non-electronic, probe pH meters, and although it seems to measure the pH of liquids great, it also seems to have a more difficult time with solids. I have a 65W CFL located about 8 inches away from the top of the plant, a 42W CFL about 5 inches away, and a 27W CFL about 5 inches away. Temperature is usually around 80, but sometimes jumps up to 85 in the night (when the heater is running throughout). I wish I could nudge the temperature down to 75ish, but that is going to be difficult to do. It is also on a 24-hr light cycle.

THE PROBLEM
The problem with the plants is that the leaf tips look like they are dying. Almost every leaf on the plant at least has a crispy-looking tip. Some, however, have extensive damage to the leaf edges (pictures attached). I originally thought older leaf sets were being targeted, but it seems to be random. However, new growth is not immediately affected (although it might look like an Iron def.). Some people who I have asked suggested nute burn, but I've barely given this plant anything! I should also add that most of the leaves exhibit a yellowish tint in between the veins and some, but not all, of the stem is reddish-purplish, which I think is another sign of deficiency.

MY GUESS
If anything, I would think it's a nute deficiency, either caused by a lack of feeding by me or a high pH blocking some nutrient uptake. But, this is my first grow so I am very uneducated on these things.

PIC GUIDE
1st Pic - lower leaf set
2nd Pic - mid leaf set
3rd Pic - Top-down view of plant

**All pictures taken morning of 2-12-10

I really need some help! Thanks in advance!!

Click to expand...

well its not a 'nute burn' which doesnt mean anything, theres only nutrient def/toxicity and id say its potassium/phosphorous deficiency , a lack of potassium will stop the plant from being able to control leaf temperatures, therefore in high temperatures , the leaf end will burn anf shrivel up like yours have. flush it with a mild nutrient fertiliser and invest in some potash
x

and high salinity and ph will lock up potassium (and other nutrients) even if there is alot of it in the soil, which explains why your low strength fertiliser didnt work.
x