Info: FF Lightwarrior medium RO water adjusted to 5.5-5.8 Technaflora BC nutrients Following recipe for success at half strength @700ppm 5 bag seeds, 1 Super Skunk Ranging in size from 22-26" tall 8x10" pots Water, Water, Feed schedule @4 weeks into 12/12 Symptoms: Lower to lower-middle fan leaves are nearly completely yellow. Progressed from the leaf tips inward with necrosis on some outer edges between the veins. Some yellowed leaf tips are curled upwards also. Veins were the last part to turn yellow. My best guess so far was possible N, P and Mg deficiency. To combat this I added some BC Grow to the recommended flowering mixture and additional CalMag. I have not seen any positive progress so far and am now worried my problems are caused by PH and looking for some suggestions before proceeding. Middle and top of plants look good with buds ranging in size from pencil eraser to marble size. The pictures (if they will load) don't indicate an Mg issue but prior to taking these photos the yellowing on some leaves was starting between veins toward the leaf tips and progressing inward. That's why I'm thinking there is a Mg issue also. Need help on this one real bad.
There aren't obvious signs of Magnesium deficiency but you're right about the Nitrogen & Phosphorus. N-def causes the whole-leaf yellowing and P-def causes the shriveling tips & necrosis. The P-def appears to be much more mild than the N-def. Add more N and switch the schedule to water/feed/water/feed. The increased fertilization frequency should cover the Phosphorus for now. You'll need to start easing off on the Nitrogen soon after increasing it because flowering plants need progressively less N as they mature, but you want to start this progression from a higher level of Nitrogen. As the buds get larger & you lower N levels, increase P & K.
Thanks, at least I was on the right track. What do you think about the ph? I've seen nutrient uptake charts list soiless as low as 5-5.5 for optimum uptake. My mix is pre balanced for 6.3-6.8 though and I've also read some thread where people recommend 6-6.5. What's your take?
You don't look soilless - keep pH between 6.3-6.8, roughly. Your deficiency could simply be from the pH being off.
It's s.peat moss, perlite, worm castings, oyster shell, and granite dust. Would that be considered soil-less or soil? I was leaning towards adjusting the Ph up a bit. The threads I've been reading seem to agree with that option. I'm gonna bump the PH up and add a bit of grow nutes for the deficiencies and see how that works out. Thanks folks!!
That's soil; however, since your growing organic your root zone should equilibrate itself to a good pH - the microbes like the same pH as your roots. This would explain your issues, as your watering pH's are conflicting with your soil zone pH. Also, how are you getting RO water to maintain a pH? distilled and RO should have no ions, and therefore no stable pH. and as food for thought, the buffer you add to the RO can be messing with your soil zone as well. If you've got a good soil with nutes present in the form of organics, you shouldn't have to pH your water at all as long as you have healthy microbial life down there. However when the buffer comes in it will likely kill your soil life. NEVER ADJUST pH AND ADD NUTES - this can create BURNS. Only adjust pH, followed by nutes if the pH doesnt help - your soil HAS nutes.
Not talking about a normal feeding: Scenario A - liquid nute grower feeds his plants in FFOF @ 5.5 pH. His plants grow really slow and show deficiencies in the bottom half of the plant. His ppms are at 400, which were increased up to 600 as the deficiencies progressed. Unused salts build up in the soil. pH adjusted to 6.4 next watering, ppms kept 600, plant is burned. Scenario B - Same dude is now growing same plant in hydro. Rez is at 500 ppms pH 7.0. Plant is growing stuntedly-slow. Next rez change ppms are upped once again to try and fix obvious deficiency. Few days later this grower realized optimum pH is at 5.8, adjusts accordingly, plant is burned. Basically, pH being off mimicks REALLY LOW nutrient levels as the pH either makes nutes lock together or ppt out of solution, unavailable to the plant. Increasing the amount of nutrient in only very slightly changes the amount available to the plant. When the pH is fixed however, all those nutrients are suddenly available to the plant. The plant is definitely NOT used to this nute load and may burn even with slight nute increases. The plant will for-sure burn if one would drstically adjust the ppms up by say, 500-->1000 in eventual, succesive, rez changes, trying to fix a deficiency but ignoring pH, followed by the pH adjustment. What i'm advocating is keep ppms at the 500 mark, or next rex change bring them back down, and adjust the pH FIRST to see if that fixed any issues. If it doesn't, you need more ppms - fix the pH first before you add more nutrients
Sounds like a plan. Initially that is what I was afraid of doing by adding nutes for the deficiencies if my problem was Ph related. Turns out based on your advice and some reading I've realized Ph IS my issue. Flushed my plants today to get rid of excess nutes before adjusting Ph with next feeding. As to your question about the RO water Ph, that is something else I was doing wrong it seems. I wasn't aware of the facts about RO water and not having anything in it to act as a buffer so adjusting the Ph is pointless cause you can't get a reliable reading. I double checked my water and I'm getting a Ph reading of 6.08 and PPM of 14 for my plain RO water. I am on a well with above average iron and sulfur content that is run through a softener before being RO'd. As far as my soil goes, what is a soil-less medium exactly? I was under the impression that these mixes with a base like peat moss or coco coir were soiless. I don't want to make the same mistake again if I use different medium next time. And since I've been using Ph Up/Down so far and have probably killed the beneficial microbes in the soil, would you recommend getting some mychorrizae (sp?) to add into my soil? Thanks!
Your peat moss is soil - because you mixed it with other things, mainly the rock-dust and worm castings. Peat moss on its own might be considered soil-less. Coco would be soil-less, if you don't add anything to the mix. Soil-less is basically anything that's not a soil - no mineral additives, no nutes within it, no living microbes initially - usually just an inert substance that the plants can grow in, such as coco or hydroton spheres. Pretty sure for something to be "soil" there has to be a wide spread of particle sizes as well However when I hear soil-less I'm thinking of a play on hydro - ebb and flo in perlite / red lava rock. I suppose coco fits in there too. Straight hydro / aero systems require the same pH as "soil-less". pH adjustments thru buffers may not kill your bennies; its just my thought as we, us humans, can't handle going from 10 degrees C to 100 degrees C all the too well in our environment - I apply this to the soil-zone. If you really want to re-stock your soil-zone, you need more than just mycos - grab some earth worm castings. They are much more diverse in what they contain. If you want to take it a step further, Google white slime root cure, first link. That's the tea I brew for my hydro application to fight off root rot, and now I use that tea diluted to water my soil plants. It has every beneficial you could possibly want, and more. Recently I've added kelp meal and glacial rock dust, as well and bone and blood meals, to that recipe to see if I can't get even better results - can't wait until this batch is done, because all previous batches just made my plants GROW, without fear of rot or fungi.