Think this is from a PH problem (see pic below)? I have a Milwaukee PH meter that is starting to give inconsistant readings even when calibrated. The strain is DNA Sour Cream and it started out yesterday with purplish spots on one leave and has now spread to another leaf. In a few days heres gonna order a Bluelab combo meter. Its in Botanicare coco 75% with 25% perlite and some pelletized garden lime. Nutrients used every third watering is Technaflora line and regular watering is tap water that sat out for 24hrs with some unsuphered molasses and some MagiCal for some extra calcium and magnesium, I dont use the MagiCal with every regular watering, about every second regular watering. The PH reading of the nute or water is right about 5.8 going in but is now reading over 6.0 on the run off. Only one of my seedlings is showing this problem and the other looks fine and so does the Romulan clone. The reason I think its the meter is that one minute the nute or water can read 5.8 then 30 seconds later have a different reading plus or minus .10 or more. Link below is the meter I`m looking at buying. Bluelab Combo Meter conductivity, pH, & temperature
I think you're underfeeding your plant and starving it to death. here's a step by step diagnosis help for you since we can't see the whole plant. Marijuana Nutrient Disorders I've never cared about my pH beyond it being less than 6 and more than 5. I can't see .1 being worth a damn as far as causing problems. I feed with every watering in my coco. Plants seem to appreciate it (7 different strains so far)
I agree you cant be afraid to feed. I am growing afghan kush auto's right now about 35 days old and getting 1500 ppm of floranova and loving it. when it was at its 5th node it was getting around 700-800 ppm cause thats where I start. most ppl start a gh lucas formula at full strength no big deal.
With this new meter a full nute feed the ppm reading is over 2000. I think this DNA Sour Cream is more sensitive to nutes or something else then the other two plants, 1 a Romulan clone and the other a Blueberry Gum that was started from seed at the same as the Sour Cream and both are the same age and size but yet those two show no signs of problems. I have flushed the Sour Cream and not given it any nutes other then unsulphered molasses every other watering for a week now and the problem hasnt spread to any other leaves and the plant is looking better. All my other plants before this one I have always started them off at full strength nutes around 2 weeks without any signs of problems like that the Sour Cream has.
From what I been reading here a few others are having other problems with the DNA Sour Cream and one person hasnt had any problems, AskEd had two seedlings die and another person is having a different problem with his. I`m gonna try doing a nute feed at half strength today and see how it goes.
And I would be that other person. My problem with the Sour Cream is that it looked large an healty above ground, but it hadn't really filled out the root zone yet. My other plants were healthy up top but most were not as large as the Sour Cream. I wound up over watering the Sour Cream about 9 days ago. Since then I've added maybe 6 ounces of water and the top of the coco is still moist... Some of the other plants, like my Wappa for example, has been watered 3 times to the Sour Cream's once... I'm running my ppm's around 600 right now and it seems like my plants are starting to get really hungry. I'm going to bump up the ppms a bit, probably closer to 750 or 800, on the next watering to see how it goes. 2000ppm sounds wild! My meter only goes to 3000ppm. I would imagine that feeding that strong would create a problem down the road if you did it every time. Probably should use a little plain water with some run off if you feed that strong I would think. Maybe not though. Just sounds crazy to me because I'm at like 1/3 that strength
From what I've seen 1300ppm is about the upper end of commonly used. I use the directions on the back of my bottles (all Botanicare) and I water about every day to every other day. Towards the end of flowering they seem to stop taking as much water. I do not know how in the world you managed to get coco to stay wet for more than a couple days. I've always thought it impossible if you have any drainage at all. You've got the beginnings of inter-veinal chlorosis but they look otherwise mostly ok. A little saggy. Try upping the nutes. Seriously, they can ONLY grow as much as you provide mass for in the way of nutrients. Coco is non-nutrative/inert. They push roots through the coco but they can't eat it. So, the only way for them to gain mass is for you to provide that mass in the form of nutrients. Photosynthesis only requires co2 and light true, but that only produces sugar which the plant uses for energy. It's only going to gas as much mass as you put in of ferts. Now you just have to put them in in sufficient amounts and in the right proportions. my opinion, give em more nutes when you do water, improve container drainage and ventilation (ie, pop some holes in the plastic around your coco, roots need air).
personaly i think its a ph problem. not nutes. see 1300 ppm is a lot.and you would have some yelowing on the bottom if it was a nute def.Whats the situation on cal mag?
The Technaflora nutrient line that I use has 1 part of the mix that is Magical, magnesium and calcium mix. I also got some pelletised limestone in with the coco/perlite mix. I gave it a nute feeding yesterday that was a little more then 1/3 strength and slowly gonna up it till full strength to see if it was a nute problem or a PH. I was leaning towards a PH problems as my previous meter was giving inconsistant readings. When Phing the water it would be a back and forth thing with PH up & down, one minute it would read 5.8 then the next PH test 30 seconds later would be off as little as .10 or as much as .35 or more. It seems to have handled the nute feeding at a little more then 1/3 strength with no signs of problems sofar.
halfa: not always. Some nute deficiencies start at the top of the plant, some at the bottom. Depends on which thing is deficient. A couple of the more difficult to treat disorders start at the top of the plant.