Yellowing in early flower

[aphrodisia]

"And, once it started it seems like there is no way to stop it. Maybe slow it down at best"


Exactly which I found very frustrating as you try everything to no avail

 

[Ramblinrose1965]

Simply going by my own observations and experience. I have grown for years using HID's until the rage for Led's took over, and I have never experienced any crisping or yellowing of my plants under metal halides or high pressure sodium lamps like I do under Led's.
Like I wrote above they are brilliant for the veg stage as they produce lush growth and keep the plants bushy and squat, its when you flip over to flowering that the problems start. Every single time I have tried flowering under Led's by themselves at around 2 weeks into the flip the fan leaves begin crisping up and yellowing without fail which has certainly been a head scratcher for me as I simply can't figure out why its happening .
This is why when I flower with Led's now I always include a high pressure sodium bulb alongside it which prevents the crisping and yellowing.

I completely agree. I have never grown under anything but Leds and I'm only on my 5th grow. Veg is always great but 2 to 3 weeks after the flip I experience the same symptoms you explained.

 

[growmore15]

Hello,

last 7 rounds have trouble with yellowing during flowering time. All big leaves yellowing.

What Strain is it? greenhouse super lemon haze and super silver haze
Is it Indica, Sativa or Hybrid? What percentages? 70% SATIVA - 30% INDICA
How Many Plants? 10
Is it in Vegetative or Flowering Stage? flower
If in Flowering Stage... How Long? 24 days
Indoor or Outdoor? indoor
Soil or Hydro? soil
If Soil... What is in your Mix? 40% soil cana professional mix, 40% coco, 20% perlite
If Soil... What Size Pot? 18L 4gal
Size (Wattage) of Light? How Many? mars hydro fce 4800- 3x 450watt? 1350watt
Is it Air Cooled? AC
Temperature of Room/Cabinet? 27-30C
RH of Room/Cabinet? 50-60%
PH of Medium or Reservoir? 6,3
Any Pests? no
How Often are you Watering? 4-5 days now
Type and Strength of Fertilizers used? Plagron: calmag, terra bloom, sugar royal
Size or Square Footage of Room? 4x8 or 120x240

I have sealed room and co2 tank: 1000-1200ppm
water: RO

plants aren't getting nutrients of the proper nutrients. did you change the feed from Veg to a Flower regiment?

you mixed coco with soil? and that's a lot of perlite.

it'd go back to the basics. pick a substrate, pick a nutrient brand and follow the feed schedule from week to week as advised. love plagron but doesn't seem like you are giving the appropriate ratios

 

[Azimuth]

In an organic grow, a lack of calcium can cause magnesium to bind to, and lock up, nitrogen leading to the yellowing leaves. The nitrogen is there, just can't be accessed by the plant.

So, adding some worm castings regularly up top can help balance the cal/mag ratio and free up the N.

Plants also need N in flower and some growers cut it way back thinking the plant doesn't need it, but it does. So, if adding more N doesn't help, adding some Ca might just do the trick.

 

[013]

ditto on growmore,

don’t know what’s in the canna professional but with 40% coco and 20% perlite- at least 60% of total soil mix is inert… there’s nothing in 2 inert medias to sustain a plant- coco & perlite equates to a place where roots can grow if you supply everything the plant needs. I’m thinking the canna runs out of steam well before you get to flower….

I’m not seeing any issues from leds in flower…