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3 week old seedlings turning yellow


New Member
Hey all,
This is my problem...
Strain, blueberry hash x 3 and 1 x northern lights no 5
Light - topled 192x3 panel at 24" in height
Nutrients - weak season mix
Medium - soil with organic manure
PH - 6
Room Temperature 20c to 27c
Room Square Footage - 4 foot
Pests - None Known

Problem: I'm having a yellowing of my leaves, pale yellow with no signs of curling etc. Stems seem healthy and the leaves seems fine to touch.

Any help appreciated


420 Member

Where is the yellowing starting?

There's a lot of information missing...


What Strain is it?
Is it Indica, Sativa or Hybrid? What percentages?
How Many Plants?
Is it in Vegetative or Flowering Stage?
If in Vegetative Stage... How Long?
If in Flowering Stage... How Long?
Indoor or Outdoor?
Soil or Hydro?
If Hydro, Reservoir size?
If Hydro, Reservoir Temperature?
If Hydro, what type of Medium?
If Hydro, what type of Setup?
If Soil... What is in your Mix?
If Soil... What Size Pot?
Size (Wattage) of Light? How Many?
Is it Air Cooled?
Temperature of Room/Cabinet?
RH of Room/Cabinet?
PH of Medium or Reservoir?
Any Pests?
How Often are you Watering?
Type and Strength of Fertilizers used?
Size or Square Footage of Room?

This information is necessary for accurate support to be given.

John C

Product Reviewer - Formerly Known As KingJohnC - M
Can you please post some photographs showing your whole plants, specific issues, and grow area? Your LED light panel may be located too high above your canopy to allow proper growth.

Here is everything you should need to know to post full size photographs


You want pH 5.8 for hydroponic and soiless (peat moss and coco coir) and pH 6.5 for soil.

Here is a nutrient availability chart

Here is a cannabis leaf deficiency chart

here is the Cannabis Plant and Pest Problem Solver and the Plant Abuse Chart



Can you please be as specific as possible as to the manufacturer of the nutrient line that you are using?


New Member
The top two are blueberry hash the bottom and more affected one is northern lightsWhat Strain is it?
Indica top two sativa the bottom one
How Many Plants?5 seedlings
Is it in Vegetative or Flowering Stage?veg 3 week old

Indoor or Outdoor? Indoor grow tent
Soil or Hydro? Soil
If Soil... What is in your Mix? Organic soil mix with broken down manure horse

Size (Wattage) of Light? How Many? 300watt topled reflector 192x3watt panel

Temperature of Room/Cabinet? Between 20 degrees Celsius to 29c max

Any Pests? None visable
How Often are you Watering? Only when dry
Type and Strength of Fertilizers used? Seasol very weak solution
Size or Square Footage of Room?. 4 foot

Hope that helps guys as anything you guys advise is appreciated


New Member
Also I tried the lights at 12" and worked my way up as I thought it maybe light burn. California finest suggested 18" to 24" but it seems I'm still having the issue

John C

Product Reviewer - Formerly Known As KingJohnC - M
Have you previously grown other plants and vegetables in your soil mixture? I believe the cause of your plant leaf damage are either nutrient uptake related or your soil mixture is not working properly to supply your seedlings with nutrients. Plants grown under LED light panels have a higher demand to calcium and magnesium, I would use a calcium and magnesium supplement for your plants. I would introduce a calcium and magnesium supplement containing calcium nitrate and magnesium nitrate Such as Botanicare's Cal-Mag Plus after 2 good weeks of vegetative growth from a seedling. Cal-Mag Plus and CaliMagic are synthetic calcium and magnesium supplements. If you are using a natural source of calcium and magnesium based calcium and magnesium supplement such as General Organics CaMg+ you can start to add at the start of vegetative growth. I use Botanicare's Cal-Mag Plus at 5 milliliters or 1 teaspoon per gallon as a calcium and magnesium supplement for the majority of my cannabis plants.

(Click on the photographs for direct links to the products)



New Member
I don't think its burn my friend. Look at some of the links kingjohn posted and get some cal may in your regime


New Member
Good advice guys..thanks. To touch the leaves it doesn't feel like burn.they still feel soft. So I'm gathering calmag is the issue. How long roughly will I see the results sort themselves out? A week or two?


New Member
Actually turned out to be an iron deficiency. Due to the fact that I have used to much manure in my soil mix this year, it's given me lock out also so calmag isn't helping a great deal. Guess I'll have to change the soil over and hope for the best??


New Member
Could be a Nitrogen lack or iron defic.. Its un usual to see issues so early so im wondering if your grow medium is in need of adjustment ? Hope u sort it. Smokem..
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