Nutrient Issues During Flower?

[electricbuddha]

Hi -

I am about to start week 7 of flower and starting to notice some potential nutrient deficiencies in one of my plants. The plant is in Fox Farm Ocean Forest soil and it's been getting Fox Farm trio nutrients (based on the schedule, not 100% strength) - currently ~1500ppm for feedings. I alternate feedings and waterings so it's fed about every 3-4 days.

See pics for reference but some of the leaves are yellowing / dying and falling off (I'd estimate ~20 fan leaves / week). Is this normal during flower? It's only leaves under the canopy that are affected so I'm thinking some of it may be light issues (I did lollipop the plant but maybe I should have taken off more...). I have 2 plants in the tent - each under 100W LEDs which should be sufficient for that tent size. The leaves up top look fine (besides some thrip markings...I took care of that) - is the plant just re-directing energy up there? What's confusing is when I first noticed this I bumped the ppm for the feedings to ~1700 (thinking it was lack of nutrients) but now I'm noticing some nute burn...planning to dial back down to 1500 for the next feeding.

Any advice would be appreciated - this is my first grow so not 100% sure what to expect in flower.

Thanks!

[CaptainWiese91]

Looks like deficiencies to me. Looks like it’s P and K and maybe some magnesium also it wants.
usually the plant will take from the lowest leaves in my experience.
and mid flower and to the end they get really picky about the nutrients and PH in general. I’m not seeing you mentioned the Ph? Is that in the correct range ?

[electricbuddha]

Thanks - I have been ph balancing to ~6.5 every feeding / water. I have been giving it aprox. the same ratio of Fox Farm "grow" (mostly Nitrogen) and "bloom" (mostly phosphorous). Usually a little more bloom - but maybe I should reduce the N at this stage? I also do 1tsp cal-mag / gallon every feeding & watering as well.

[dilvish]

nutes should be once a week in soil. every other watering should be a flush. Depending on your heat and humidity levels it could be an overwatering issue or a combination of ROOT issues. That's a fair sized plant so it could be root bound in that pot.

make sure you are checking the soil before watering...it needs to dry out a bit before adding more and remember the cooler the temp the slower the evaporation of the water in the pot. temp at that stage should be around 70F-75F around maybe 40% humidity.

PH levels of your watering should be around 6.5

[electricbuddha]

Thanks - it's in a fabric pot which I've heard doesn't cause plants to get root bound since the roots are "air pruned." Temp in the tent is always right around 75F (remote sensor with heater) - I'm in Colorado so its dry but the humidity is usually around 30-35% in the tent. I pH water / nutes to 6.5.

So you think the issue could be that I'm giving it too much nutrients or watering too often? During veg I always let the soil dry out totally until the plants were almost wilting - I heard that was mostly for root development - and since that isn't as important in flower I haven't been as diligent with letting the soil get totally dry. My thought being that it's much worse for the plant to wilt during flower. I really have no idea though just gathering advice / info from the internet Appreciate the feedback!

[CaptainWiese91]

Nutes doesn’t have to be put in the soil every week. Depends a lot on the grow, the soil and the plants. So it’s not a standard
answer, sorry to say that.. It will just confuse people more if you throw out that answer every time you reply to a new grower

[Tedtheclown]

Depending how far she has left to go, last few weeks you really dont want to give nutes. Let the plant use all the energy from lower leaves. Some may agree or disagree

[SoOrbudgal]

I'm jumping in because i agree with the Captain. It's not the fabric pot. My thoughts are it's the need of P-k less N for sure. And as hard as it is you do need to rinse out those roots now and then plants like a fresh drink of plain water. I got the same humidity where i live in Oregon do to wood heat has always been issue in winter grows. Yes do remove lots of those old fans and open up the center more light. Hey you done real good with these it's just the too frequent N that's causing a imbalance. I do like alittle N with the bloom my bloom is at 5-10-5 NPK could perhaps use more PK but i also use unsulfurated molasses with the watering during the stage of bloom your at.

[electricbuddha]

Thanks! I think the issue may have been that I was giving it too much "grow" nutes (N) during flower. Also maybe salt buildup in the soil was causing some nutrient lockout. I flushed the pot really good with plain water and I'm just going to give it more "bloom" nutrients going forward and scale back the N - in addition to the organic base nutrient and cal-mag.

You mentioned molasses - from what I've read this only really helps with organic grows? Because it feeds the microorganisms in the soil but if you're using chemical nutes molasses doesn't really do anything? That's what some people on the internet say

I'm going to use Fox Farm cha-ching for the last week before the final harvest flush.

[CaptainWiese91]

Well I use molasses. But I use it the last 3 weeks of flower, and the last 3 weeks of flower I’m not using anymore nutrients, organic or synthetic doesn’t matter.
I can see from my experience the molasses is helping my roots in my soil.