necrotic patches on new leaves

[elwood]

hey so im running two plants at the moment, one about 2 weeks older than the other.

They are in a cupboard with a 400W HPS bulb, running on 18/6.

Im using Greendream 1 (one part flairform nute) at an EC of 0.7 and a pH of roughly 5.5 (can't be exact because im using a colored indicator mix).

The largest plant has purple stems and some pretty nasty necrotic patches on the lower leaves (which i cut off only to find that they then appeared on the previously healthy parts of the leaves) but it's now also getting some on the tips of the newer leaves. The younger plant is also showing some necrotic patches on it's leaves with a little bit of yellowing.

I just realised yesterday that the pH i was running it at was about 6.5 so i was thinking it was a lack of phosphorous due to pH lockout that was causing the problems but just wanted to ask some more knowledgable people here before i did anything drastic.

Take a look at the pics and let me know what you think, this is my first grow and im really hoping for a decent smoke so am pretty anxious about the health of my babies.

[SukonmiSkunk]

looks to me that your ec might be too low.. when the lower leaves start to yellow that would be a nitrogen deficiency also youve got some rusty spots which i think is a magenese deficiency.. .

 

i dont think youll have a nutrient lock with the plants being so young

 

im guessing your hand watering... are you watering with water every few feeds?? also how much run off are you getting when you water? how often are you watering?

 

i would be tempted to give it a good watering with just plain water.. make sure theres plenty of run off.. about 2/3rds.. then straight back onto nutes.. id be upping the ec to around 1.4.. or around 12-1400ppm..

[elwood]

oh sorry im running an autopot set up with a 50/50 vermiculite, perlite medium. So the plants have water all the time. EC of 1.4, will this put the little one at risk of nute burn? it's still quite small. Should i up it gradually or just jump straight up?

[SukonmiSkunk]

so no drainage at all?

 

that might be the issue.. wet feet.. ?? toxic water in the bottom of the pot??

 

not sure.. but it shouldnt be burning at that EC..