Showing some early signs of some sort of deficiency, having a hard time diagnosing

Hello folks, I have two auto plants in the early-mid flower stage. One is Auto Speed Bud from Female Seeds, the other is a Bubblicious from Nirvana seeds. Aside from some slow growth early on (I was using some really weak LEDs, have since upgraded to a 300W (~150W actual draw) LED) the plants haven't really shown many problems.

In the past few days though I've noticed that the leaves around the "budlets" on the Speed Bud are turning a really bright lime green, almost yellow.

Growing indoor or outdoors: Indoor, small closet in my basement
Watering schedule: Whenever the top inch or so of medium feels dry
Growing Medium: Soil (Dr. Earth Pot O'Gold, ~5 gal pots)
What stage of growth: Early-mid flowering (7 weeks from seed with an autoflower)
Nutrients: General Hydroponics GO line -- BioThrive Grow, BT Bloom, Big Bud, CaMg, Diamond Black, BioRoot, and the others. Followed the schedule on the box. Since flowering started I've been feeding less than the recommended amount on the box and I've been checking pH of the nute solution and of the run-off. Last watering/feeding the run-off was right in the 6.0-6.5 range so I thought everything looked good.

Anyway, I think I've narrowed it down to some sort of deficiency or lockout but I can't be sure. It looks like it may be either manganese or iron, and I'm leading towards iron because it's really only showing on the newest growth. The other possibility is pH lockout which I find strange because I thought the run-off seemed fine when I watered on Saturday. I mean, if there's even an issue?

Here are some pics. First two are of the Speed Bud showing the problem, second one is the healthier looking Bubblicious for comparison (sorry about the poor lighting -- blame my phone). The Speed Bud pics are slightly exaggerated due to flash from my phone, they're not as yellow in plain light as they look in the pics, more of a light lime green. Am I overreacting? Is something going on, and how can I fix it if there is?

Pics in a minute... originals were geotagged.

Edit: Much better.
Speed Bud:
Bubblicious:

Anyone?

next grow add more perlite about 25-30% is good

most commercial soils are way too hot for weed

many are configured for poor or low quality soils

reading any accurate level of Hydrogen in soil is a foolish move

as the soil is in motion..constantly, and forever changing

learn to grow without this crutch !!!

keeping the above in mind autos are a different ball game

and require far less nutes

as they are on a clock little can be done

other than hold back nutes (feed at 50% less)

to my blog on autos: https://www.rollitup.org/Journal/Entry/10-top-tips-for-a-better-autoflowering-yield.30162

good luck

so, that weird lime green discoloration near the buds? Any comments on that?

new leaf growth tends to be a lighter green color for a while. you're giving way too much stuff. doesn't dr. earth soil have fert in it already?

polishpollack said:

new leaf growth tends to be a lighter green color for a while. you're giving way too much stuff. doesn't dr. earth soil have fert in it already?

Click to expand...

Dr Earth Pot of Gold is all organic, as are my nutrients. The soil does have nutrition in it, but as I understand it, organic nutrients are a little more forgiving when it comes to overfeeding, but you're right that I've been giving it too much stuff. That's why the last few feeds I backed off and gave half or less than what is recommended on the feeding schedule.

it might be possible to give nothing, at least for several weeks.

Those plants look over fertilized to me too. And in a soil mix I wait until the pots are dry 3/4 down the pot. The mix holds much more water when the top inch is dry than you think. The pot should feel alarmingly light before watering.

During periods of rapid growth the centers of the growing tips look lime green for a day or more until the chlorophyll greens up and is a good sign. If it doesn't green up and gets worse icluding older leaves then it looks like an iron deficiency that can be brought on by an imbalance/excess of other nutes like Ca, Mg, P or K. Or the pH being too high will often cause micro-nutrients to be locked out.

When watering don't go by the top couple inches being dry. Rookie mistake. Lift the pots to get a feel for the weight and they should feel real light before getting a thorough soaking. Tip of the hat to MichiganMed for pointing that out. Judging by the first couple of inches can leave old, stagnant water in the bottom half of the pot which leads to root rot and and symptoms of the plants drying out and drooping when it's really over-watering causing the problems.

The top couple inches dry out fast due to evaporation and the fact that water wants to sink down in the pots.

When using a rich soil no nutes should be added for quite some time and often not until the plants are ready to flower and maybe showing a little yellowing of the very bottom leaves indicating that the natural levels of N and other nutes are becoming exhausted. I'd just give them water for the next few waterings as the very dark green shows excess nutes now.