Hey, this thread is a little old but I figured I'd give it a shot. So I'm a month into flowering with my first cycle now, and two days into flowering with the first batch of matured clones.
The four plant scrog that is 30 days into flowering has some sort of deficiency issue (or possible burn??) going on with all 4 plants. We realized our PH meter is junk and have since decided not to rely on the readings. Here's the feeding schedule...
Medium: Pro Mix BX
5 gal pots
master kush scrog
veg: 2tsp gro big / gallon
2drps Superthrive
1/2-1 tsp PH up (water had low PH levels, around 5.3 after adding nutes, so we raised the PH to 6.8 to correct during veg and plants bounced back from the initial yellowing and necrosis issues)
Flowering: 2.5 tsp tiger bloom
1/4 tsp open sesame
4 tsp PH up
1 drop superthrive
Plants initially looked healthy. Upon introduction of the first full strength nutrient mixture for flowering (3.5tsp/gal tiger bloom, 3tsp PH up, 1 drop superthrive) they still looked healthy, no signs of burn or deficiency. They were watered again on 9/19 with the same nutrient mixture plus 1/4 tsp/gal of open sesame. Two days later the leaf tips were turning brown and dying so the plants were flushed on the next watering.
on 9/25 they were watered with 1/2 tsp open sesame per gallon, 3 tsp PH up, and 1 drop superthrive. On the 28th they again got full strength with 3tsp tiger bloom. More signs of burn or deficiency progressed, so on the next watering the open sesame went from 1/2tsp /gal down to 1/4tsp / gal and half the PH up. On the 4th the plants were again watered with less nutrients, this time 1.5tsp tiger bloom, 1.5 tsp PH up and 1 drop superthrive.
The plants have dead brown/yellow leaf tips that are seeming to curl up rather then down. The blades on fan leaves are all yellow at the tip but not curling up or twisting like Mg deficiency. The thought initially was that chemical burn was the problem, and the plants were flushed with straight water and then followed up with a lower strength nutrient mixture. After things kept progressing the thoughts turned to PH problems and possible nutrient lockout.
During the end of Veg and for the first 3 weeks of flowering, PH up was added to each mixture to bring it up to 6.8. This was because the runoff was down at about 5.1-5.2. When our PH meter became junk and we decided not to trust it was when we realized we didn't know what the actual PH of the water was that we had been giving them. If you assume our starting level is close to 7 (just plain water), is 3 tsp/gal of PH up too high when mixed with 3tsp tiger bloom/gallon? I feel like the plants have just been getting a guestimate of PH adjusted water, which might be too high leading to nutrient lockout. Should our target PH range of the water really be in the 5.7-6.0 range for a peat based medium? Is it ok that the runoff reads lower?
Lots of information to take in, I know. Thought you might be interested in sharing your opinion nitegazer. From what you wrote about your feeding schedule it sounds like you don't use any PH up? So I would guess your nutrient mixed water (if it started at 7) would be down in the 5.8 range?
Again the deficiency is on all the leaves except some of the smaller new growth around the buds. dead leaf tips curling up and the tips of the blades are yellow and dead. Any thoughts appreciated, mainly on the diagnosing between chemical burn or PH balance being off. Buds are still looking healthy and the second round of 4 has just started flowering and is healthy. Hope things only improve from one batch to the next.
mahalo
