Seedling stopped growing and leaves turned yellow ,need help


Hi there ;

I have planted 13 seeds which were bought from a well known source, in the following condition:

Growing Method : Indoor
Soil :Coco coir + Perlite+Vermicompost
Light : HPS 400 w ,Light cycle from the beginning 24/0 ( we put them under the light 2 days after sprout)
Light source distance from the top of the plants :2m

  • air circulation fans
    Strains :Auto Tai ryders
    Temp is always between 25-32
    Humidity :not measured
    Co2:not measured
    Water PH : (Tap water 7),(RO 5)
    Water+Soil PH : nearly 7

Everything was fine,leaves were fine green and growth was satisfactory until 8 days , since then their growth have been so slow even I can say stopped ,then I decided to transplant them from paper cups to plastic pots 3 times bigger ,with holes at the bottom ,after that nothing good happened and their growth was still not obvious ,on the other hand after some days lower leaves started to turn to yellow and got dried with brown spots appearing at first .

My friend watered them with so little water without letting water to drain from drainage holes .
I changed it to standard watering , but saw no results again.We let the top layer of the soil to be dry and then watered the plants with letting the water to run from drainage holes.
Even I changed the water from tap water (PH 7) to purified RO water(PH5) ,again with no results.
One thing that is so abnormal to me is that ,after switching to standard watering ,tiny white hair like things appeared at the top of some of them ,I got confused that if they are entered flowering stage so soon !!!
I really don’t know what to do now .
Last thing to mention is that when I started to water them properly the running water from the bottom holes was completely yellow in color ,is that all right ?
Also I want to know if there should be air circulation from the bottom holes ?

Could you please help me to find my problem to solve it .
Your help will set me free :slight_smile: ,cause I’m totally freaked out right now.
Thank you so much indeed.


Are you using any fertilizer?


pH 7 is a little too high and pH 5 is waaay too low, you need to make it pH 6.5 all the time for starters

Edit: I just noticed you’re using the coco and I am not familiar with it. I do think your pH is off but definitely somebody else can answer it better for you
-good luck


Picture of Phosphorus being locked out from cooler temps

This pic is why and believe its Phosphorus
This is large but copy andadte it for future reference

Solution For Cannabis Phosphorus Deficiency

1.) Adjust pH to Correct Range

Your cannabis plant may show signs of a phosphorus deficiency if the pH at the roots is not in the right range. That is because when the pH of your root zone is off, your cannabis cannot properly absorb phosphorus through its roots. Therefore the first step is to ensure that you have the correct pH for your growth medium. Learn more about pH and cannabis.

Phosphorus is best absorbed by cannabis in soil at a root pH of 6.2 - 7.0. Phosphorus is best absorbed by cannabis in hydro at a root pH of 5.5 - 6.2. If you believe you have a cannabis phosphorus deficiency, it’s important to check the pH of your root zone to make sure the deficiency isn’t caused by the pH being too high or too low.

If you suspect your growing cannabis plant has a phosphorus deficiency, flush your system with clean, pH’d water that contains a regular dose of cannabis-friendly nutrients that includes phosphorus. This will remove any nutrient salts that may be affected the uptake of phosphorus and help restore pH to the proper levels.

In soil, phosphorus is best absorbed by the roots in the 6.2 - 7.0 pH range (in soil, it’s generally recommended to keep the pH between 6.0 - 7.0, but phosphorus specifically tends to be best absorbed above 6.2 and below 7.0)

In hydro, phosphorus is best absorbed by the roots in the 5.5 - 6.2 pH range (in hydro, it’s generally recommended to keep the pH between 5.5 - 6.5, but phosphorus specifically tends to be best absorbed below 6.2)

2.) Take Good Care of the Roots

Wet, compact soil or overwatering can trigger a phosphorus deficiency to appear even when all other factors are perfect. So make sure you water your plants properly every time to help prevent a phosphorus deficiency.

3.) Provide the Right Temperature

Cooler temperatures lower than 60°F (15°C), as well as large temperature swings, can make it harder for the plant to absorb phosphorus. Cannabis plants are therefore more likely to show signs of a phosphorus deficiency when the temperature drops too low, or if they go through a cold spell.

Cannabis likes a comfortable room temperature (they like about the same temperatures as we do).

Read the cannabis temperature tutorial

4.) Give the Right Nutrients

Most growers have actually already given plenty of phophorus to their cannabis plants since it is found abundantly in quality soil and cannabis-friendly nutrients. However, even if you are giving phosphorus, it’s important to give your cannabis the right ratio of nutrients.

An excess of Fe and Zn may cause the symptoms of a phosphorus deficiency by preventing the plant from being able to absorb phosphorus properly. If you believe there may be a buildup of nutrient salts in your growing medium (or if you are growing in hydro and have not recently flushed or changed your reservoir) you should make sure it’s not an excess of other nutrients that is actually causing the phosphorus deficiency to appear. Flush your plant thoroughly with properly pH’ed water containing a regular dose of cannabis nutrients including phosphorus, or completely change your reservoir if you believe that an excess of nutrient salts may be causing the phosphorus deficiency.

Sources of phosphorus:

Bat guano (phosphorus is readily available, especially if made into a teat)
Bone or blood meal (takes quite a bit of time to break down in soil unless made into a tea first)
Worm castings or worm tea
Soft Rock Phosphate
Fish meal
Most cannabis-friendly “bloom” or “flowering” nutrients contain high levels of phosphorus to aid in flower production, and phosphorus from a liquid nutrient is one of the most readily available forms of phosphorus you can provide to your cannabis plants
If you’ve tried everything else, then you may try adding a higher percentage of phosphorus to your feeding schedule and see if that helps clear up the problem for your plant. Cannabis plants love phosphorus, and therefore it is unlikely that you will give your cannabis too much phosphorus.

Most nutrient systems that are formulated for a plant like cannabis will carry and abundance of phosphorus, especially in budding/flowering formulas, so it is unlikely that you will see signs of a phosphorus deficiency before other nutrient problems when using nutrient systems formulated for cannabis (as long as you keep your root pH in the correct range and prevent the plants from getting cold or being overwatered). If you’ve got very high powered lights, or if your plants are growing in direct sunlight, they may be going through a lot more phosphorus in the flowering stage than average and may need you to provide extra phosphorus to make sure buds get as big as they could be.

Just remember that if there’s no actual phosphorus deficiency currently appearing on your cannabis plant, adding more phosphorus is probbaly not going to help plants grow better or make bigger buds - in fact adding too much phosphorus may actually hurt your plants by preventing the uptake of other nutrients! While it’s difficult to overdose your plants on phosphorus, adding too much compared to other nutrients will often cause other strange & unexpected deficiencies to appear.

5.) Take Good Care of the Roots

Phosphorus deficiencies can show up with the plant is having root problems or if the plant is overwatered, even if the pH is right and the phosphorus is there. Proper watering practices help plants grow healthy and avoid a host of problems!

6.) Watch for Recovery

After going through all the above steps, watch to make sure that the phosphorus deficiency starts to clear up within a few days to a week or so. After a phosphorus deficiency is cleared up, the problem (brown spots, unhealthy lower leaves, red/purple stems, etc) will stop appearing on new leaves, usually within a week.

Please note that leaves which have been damaged by a phosphorus deficiency will probably never recover or turn green, so you want to pay attention to other leaves for signs of recovery.

If you cannot get rid of your phosphorus deficiency, please consult our 7-Step Cure to 99% of Cannabis Growing Problems

Leaf Color:
Edges Appear Brown or Burnt
Pale Color Leaves
Yellow Leaves - New Growth
Yellow Leaves - Lower, older leaves
Dark or Purple Leaves
Black or Gray Patches on Leaves
Red or Pink Color on Leaves
Brown or Dark Spots
Mottling / Mosaic Pattern
Leaf Symptoms:
Upper Leaves / Newer Growth Affected
Lower Leaves / Older Growth Affected
Small Inner Leaves Affected
Leaf Edges Appear Burnt
Leaf Tips Appear Burnt
Leaf Tips Die
Thick Growth Tips
Red Stems
Mottling / Mosaic
Old Leaves Dropping Off
Slow Growth
Twisted Growth
Abnormal Growth
Leaves Curl Under
Plant Symptoms:
Red or Purple Stems
Weak Stems
Old Leaves Dropping Off
Slow Growth
Twisted Growth
Leaves Curl Under
Too Short
Root Symptoms:
Slow Growing
Other Symptoms:
Buds Not Fattening

Hope this held



Not any fertilizer yet .
First I thought they are in seedling stage and I should refrain from adding fertilizers.
Also today I noticed my soil is COCO COIR +Perlite+Vermicompost


Thank you for your detailed help,I’m going through it.


Thanks for your advice.


I think I’ve found the problem .
It was my overlook !!! that thought COCO COIR ph is equal to soil ph ,as @garrigan62 said the core
burden is Phosphor deficiency and other nutrients like Manganese and Boron which are absorbed
best at 5.8


It looks to me like the plant is starving, harsh word but reality. I have grown in coco most of my time. It has no nutrient value - nothing.
So A phosphorus lock out is a deficiency, the plant is not getting it.
And I might be wrong but I think the plant is using up its older leaves to put the needed nutrients into its newer growth. Its cannibalizing, like they do when we are finishing them in flower after washing out the medium/soil.
If you have a good fertilizer with phosphorus then give it to the plant, probably not at full strength but see what happens.
Its a responsibility that I am reluctant to take on but if they are not growing then "got to do something different"
I have never seen those white hair looking things. But I am going to look into it.
Coco wash will be yellow.
Your lights are at 2m= 6 feet? and you are using HPS. I use MH during veg then go to HPS for flower. It looks like your getting good light, just want a clarification on your ticket.
PH is high and needs to be brought down to 6. This might happen as you get the plants back on their feet.
Right now don’t over do anything, just small changes in PH starting with adding nutrients with its water.


Thank you very much for your time being set on this.
Yes my light is 400w HPS ,because of strong heat I had to hang it that high.
What do you think about KH2PO4 fertilizer ,my friend suggests it .
Also I think because my seeds are AUTO ,then those hairs maybe are the sign of them entering
flowering period prior to having enough growth !!!
Furthermore , I am not sure if VERMICOMPOST mixture too is considered soilless ?

Thanks again.


Your very welcome Mag.Mag.
I hope to encourage and help where I can.
Best regards


Hi Jeffro ;
Today I bought 20 20 20 NPK Valagro fertilizer ,where I live there isn’t much choices .
I’m not certain how much and how often should I add this to water and how !
To be honest I have read a lot about it to the point that I’m confused now.
Because you have experience with coco ,could you please advice me .

Thanks .


Is the fert designed to mix in water? or is it pelleted and time release.


Valagro is Italian and looks like good quality stuff with a seaweed base.
Vermicompost is another word for worm castings, personally I did not know that.
It is a strong fertilizer, so have to go light especially in the beginning.


It is water soluble ,I dunno how much to mix , how often feed the mix and in which way :frowning:


I would recommend reading the box or Package directions and then starting with one quarter to one half their recommended dose and observe the results
-best wishes


I bought 1 kg. then they put it in a plain separate package without any directions ,I was in hurry and couldn’t talk to the seller


Today a fertilizer seller sent the following image of his stuff acclaiming it’s ORGANIC.
I couldn’t find anything about it in the net ,it sounds fake to me ,does anybody knows

anything regarding this fertilizer ?


I’m changing water’s PH slowly toward 5.5 ,5.8 ,mixing two different waters.
Also I fed them with NPK 202020 ,1/3 tea spoon per 1 liter water.
Plants overall condition now is fine ,they seem get to live again .
But no growth !!!
I’m wondered if my try is useless ,because they are AUTO ,and their programmed growth
has been hindered totally and my effort wouldn’t have any results !!!


Sorry Mag. Mag I have never grown auto’s