Why are my seedlings turn yellow

[fuehrio]

I bought a grow tent set and started to grow these 3 plants but why are they turning creepy yellow and it seems they don't really grow as well, one of them looks a bit better but still weak. The first 3 weeks I had them on the balcony and looked a bit healthier back then. The large plant is about 3 weeks older and I keep it entirely outside on the balcony. Despite my balcony gets only about 6 hours direct sunlight, this plant looks quite good to me (will trim it soon). On google search it can be any cause, too much or not enough water or light, PH level or whatever.

 

Has anyone any idea why? I suspect most likely insufficient light and I should move the LED lamp much closer?

 

 

[stoner]

what food are you using ? 

do you ph your water ? what ph if you do.

what is that soil mix you are using ? where was it purchased ? 

what seeds are they ? 

what watt is the led ? how far from the canopy is it ? 

how often are you watering ?

were the smaller ones green when they were put into the tent ? 

 

without being there my guess is over watered and overfed. 

Edited August 23, 2022 by stoner

[fuehrio]

1 hour ago, stoner said:

what food are you using ? 

do you ph your water ? what ph if you do.

what is that soil mix you are using ? where was it purchased ? 

what seeds are they ? 

what watt is the led ? how far from the canopy is it ? 

how often are you watering ?

were the smaller ones green when they were put into the tent ? 

 

without being there my guess is over watered and overfed. 

Many thanks, appreciate. From the number of your questions I might need to do much more care.

 

I didn't give them any "food" or fertilizer yet as I thought too small and would burn the roots. The large plant, I gave organic fertilizer tablets when it was about 10cm high. Also I haven't PH'd the water and using standard soil from a gardening shop. The seeds are quality seeds from Herbies (autoflowering). The LED is a Hempeas GD2000 300w 3200-4200K,5200-6800K + 760nm Full spectrum (grow tent is 1.2x1.2 meters). The smaller ones where greener when I had them first outside but also started to fade yellow and I thought it was due to the recently bad weather without sunshine. So that's when I moved them to the tent.

 

How should I start to tackle this problem? I guess first check the PH and soil nutrition? This morning I already moved them closer to the light.

[Mr Meeseeks]

They are locked out of nutrients, possibly due to hot soil, lack of oxygen in the soil and overwatering would be my guess.

 

I recently had the same problem growing seedlings in Thai soil that was ready-mixed to grow cannabis. I foolishly thought I could just let them grow in soil and water with low maintenance, top feeding now and again. Within days of emerging they started to turn yellow and were locked out of nutrients.

 

I repotted them in my coco and perlite mix and fed them synthetic nutrients, within 48 hours they were back to life again and a lush green colour. Now they have doubled in size in 24 hours and going great guns. 

 

I have had far better results with coco than soil here, even when have premixed the soil myself. 

[fuehrio]

2 hours ago, Mr Meeseeks said:

They are locked out of nutrients, possibly due to hot soil, lack of oxygen in the soil and overwatering would be my guess.

 

I recently had the same problem growing seedlings in Thai soil that was ready-mixed to grow cannabis. I foolishly thought I could just let them grow in soil and water with low maintenance, top feeding now and again. Within days of emerging they started to turn yellow and were locked out of nutrients.

 

I repotted them in my coco and perlite mix and fed them synthetic nutrients, within 48 hours they were back to life again and a lush green colour. Now they have doubled in size in 24 hours and going great guns. 

 

I have had far better results with coco than soil here, even when have premixed the soil myself. 

Many thanks, so I will order and try out the coco and perlite mix. I noticed another thread in this forum about it which indicates the feeding is required on a daily basis. I'm afraid they may won't survive until the coco arrives but it's the price for learning.

[DontDoubtMe]

looks like a PH / water problem.

 

a while back i tested normal bottled water and the ph was over 7. which is too high. so if you are just using bottled water or even tap water, that is probably the issue.

 

also tap water has many chemicals in it, so if you use it set it outside (out of the sun) for a day or 2 to let the chlorine evaporate out.

 

get a ph pen on shopee (also get an ec pen so you can check the ppm of the water you feed it). also buy some ph up and down. these are must haves for growing weed.

 

coco is a good way to go, but also a proper soil mix is good for beginners as well.

 

the soil looks pretty compact. roots could have being having trouble growing.

 

EDIT:

the feeding on a daily basis is for coco mixes. in soil (especially when seedlings), you dont need to water every day. i used to water every 3-4 days in soil.

 

 

Edited August 23, 2022 by DontDoubtMe

[Crossy]

I second the over-watering and compacted soil.

 

Meanwhile Madam's plants are going great guns on slightly shaded sunshine, home-made compost mix (well-rotted garden waste, chicken droppings, coco and sand), along with tap water.

 

I still don't know what's she's going to do with them as neither of us fancy smoking the stuff, it will probably end up in her DIY "herbal" tea (mostly mulberry leaves at present).

[DontDoubtMe]

also, how far away is the light from the seedlings? is there a dimmer switch?

 

if they were fine outdoors and went yellow after being inside, i am also wondering if there is light stress. could just be burning them up if light is too intense

[fuehrio]

15 hours ago, DontDoubtMe said:

looks like a PH / water problem.

 

a while back i tested normal bottled water and the ph was over 7. which is too high. so if you are just using bottled water or even tap water, that is probably the issue.

 

also tap water has many chemicals in it, so if you use it set it outside (out of the sun) for a day or 2 to let the chlorine evaporate out.

 

get a ph pen on shopee (also get an ec pen so you can check the ppm of the water you feed it). also buy some ph up and down. these are must haves for growing weed.

 

coco is a good way to go, but also a proper soil mix is good for beginners as well.

 

the soil looks pretty compact. roots could have being having trouble growing.

 

EDIT:

the feeding on a daily basis is for coco mixes. in soil (especially when seedlings), you dont need to water every day. i used to water every 3-4 days in soil.

 

 

I see most comments are about the soil which seems one of the main reason to me. If your water is that high in ph level them so might me mine. I will start with checking and treating the water and change the soil. Thanks.

[fuehrio]

15 hours ago, Crossy said:

I second the over-watering and compacted soil.

 

Meanwhile Madam's plants are going great guns on slightly shaded sunshine, home-made compost mix (well-rotted garden waste, chicken droppings, coco and sand), along with tap water.

 

I still don't know what's she's going to do with them as neither of us fancy smoking the stuff, it will probably end up in her DIY "herbal" tea (mostly mulberry leaves at present).

Yes my guess is also mainly the soil condition. I started to reduce watering now

[fuehrio]

14 hours ago, DontDoubtMe said:

also, how far away is the light from the seedlings? is there a dimmer switch?

 

if they were fine outdoors and went yellow after being inside, i am also wondering if there is light stress. could just be burning them up if light is too intense

After germination they were light green outside but also started to turn yellow and I thought it's the lack of sunshine these days. So that's when I moved them inside under the light. I put the light (dimmable) about 50cm above the plants. I lowered it to about 30cm since yesterday and one plant looks a bit better now whilst the other 2 still bad if not even worse.

[tomster]

1 hour ago, fuehrio said:

After germination they were light green outside but also started to turn yellow and I thought it's the lack of sunshine these days. So that's when I moved them inside under the light. I put the light (dimmable) about 50cm above the plants. I lowered it to about 30cm since yesterday and one plant looks a bit better now whilst the other 2 still bad if not even worse.

1. Lowering the lights down onto stressed plants of any age is the opposite of what needs to be done - they are already struggling to transpire and this just makes it worse.

 

It looks like you have this light:

 

https://shopee.co.th/【พร้อมส่ง】ไฟปลูกต้นไม้-โคมไฟปลูกต้นไม้-HEMPEAS-GD2000-300W-Full-Spectrum-with-IR-UV-Grow-Light-ไฟปลูกต้นไม้-i.99442487.3056845466

 

That is a 300W light at full power - it's not really suitable for seedlings. It should be on about 25% power and no closer than 70cm for seedlings.

 

Something like this would be much better (the 6500K version):

 

https://masakigarden.com/shop/led-tube-2f-15w-set/

 

When you have a healthy looking young plant with several nodes and active daily vertical growth then you can pop them under the bigger LED, which does looks like it has a decent spectrum for veg growth by what they put on the listing (although not sure I believe that PAR Chart to be honest - they don't list the diodes by quantity so impossible to check) :

 

 

2. That soil is not potting soil for young plants, as above they are getting locked out.

 

Get some of this:

 

https://www.lazada.co.th/products/plants-center-1-potgrond-h-i2003162624-s6441208580.html

 

Also get some Mycorrhizal powder - this really, really helps get the roots going:

 

https://www.lazada.co.th/products/great-white-mycorrhizae-5-20-i2986387924-s10966581283.html?

 

For nutrients the choices here are rubbish, the best I have found so far is General Hydroponics.

 

The have their 3 part which works well but is fiddly to use, they also have this which I have used on young plants at 0.25 grams per litre (you will need some cheap jewellery scales to use this product):

 

https://shopee.co.th/Maxi-Gro--10-5-14----GHE--ปุ๋ยหลักทำใบ--i.87157335.7870762290

 

https://shopee.co.th/เครื่องชั่งดิจิตอล-ตาชั่งดิจิตอล-ชั่งทอง-ชั่งเพชร--0-1--500-กรัม--i.24578886.6320228236

 

3. As above use PH corrected water at all times, around 6.2-6.5 is fine.

 

Remember Coco and Peat are inert substrates so PH is massively important.

 

Here are two options for PH meters that can be manually calibrated, avoid the auto calibration unless you spend 1,000 Baht upwards:

 

https://www.lazada.co.th/products/ph-led-ph-i1659122611-s4622618788.html

 

https://www.lazada.co.th/products/i122609286-s127996867.html?urlFlag=true&mp=1

 

You also need to be able to calibrate the PH Pens (do it at 4 & 7), so you will need this:

 

https://www.lazada.co.th/products/i1978886344-s6332054048.html?urlFlag=true&mp=1

 

Hope that helps.

 

Cheers.

Edited August 24, 2022 by tomster

[fuehrio]

3 hours ago, tomster said:

1. Lowering the lights down onto stressed plants of any age is the opposite of what needs to be done - they are already struggling to transpire and this just makes it worse.

 

It looks like you have this light:

 

https://shopee.co.th/【พร้อมส่ง】ไฟปลูกต้นไม้-โคมไฟปลูกต้นไม้-HEMPEAS-GD2000-300W-Full-Spectrum-with-IR-UV-Grow-Light-ไฟปลูกต้นไม้-i.99442487.3056845466

 

That is a 300W light at full power - it's not really suitable for seedlings. It should be on about 25% power and no closer than 70cm for seedlings.

 

Something like this would be much better (the 6500K version):

 

https://masakigarden.com/shop/led-tube-2f-15w-set/

 

When you have a healthy looking young plant with several nodes and active daily vertical growth then you can pop them under the bigger LED, which does looks like it has a decent spectrum for veg growth by what they put on the listing (although not sure I believe that PAR Chart to be honest - they don't list the diodes by quantity so impossible to check) :

 

 

2. That soil is not potting soil for young plants, as above they are getting locked out.

 

Get some of this:

 

https://www.lazada.co.th/products/plants-center-1-potgrond-h-i2003162624-s6441208580.html

 

Also get some Mycorrhizal powder - this really, really helps get the roots going:

 

https://www.lazada.co.th/products/great-white-mycorrhizae-5-20-i2986387924-s10966581283.html?

 

For nutrients the choices here are rubbish, the best I have found so far is General Hydroponics.

 

The have their 3 part which works well but is fiddly to use, they also have this which I have used on young plants at 0.25 grams per litre (you will need some cheap jewellery scales to use this product):

 

https://shopee.co.th/Maxi-Gro--10-5-14----GHE--ปุ๋ยหลักทำใบ--i.87157335.7870762290

 

https://shopee.co.th/เครื่องชั่งดิจิตอล-ตาชั่งดิจิตอล-ชั่งทอง-ชั่งเพชร--0-1--500-กรัม--i.24578886.6320228236

 

3. As above use PH corrected water at all times, around 6.2-6.5 is fine.

 

Remember Coco and Peat are inert substrates so PH is massively important.

 

Here are two options for PH meters that can be manually calibrated, avoid the auto calibration unless you spend 1,000 Baht upwards:

 

https://www.lazada.co.th/products/ph-led-ph-i1659122611-s4622618788.html

 

https://www.lazada.co.th/products/i122609286-s127996867.html?urlFlag=true&mp=1

 

You also need to be able to calibrate the PH Pens (do it at 4 & 7), so you will need this:

 

https://www.lazada.co.th/products/i1978886344-s6332054048.html?urlFlag=true&mp=1

 

Hope that helps.

 

Cheers.

This is brilliant, great advice and thank you - seems this cannabis forum becomes one of the best source of shared knowledge. Yes this is the light that was part of the whole grow tent set. So I just made the wrong thing by moving the lights closer and I hope they cope with the stress until I am back home. This type of soil was also recommended by another experienced grower. Will do some online shopping now and further hope the plants don't die in meantime so that I can update here on the success.

[tomster]

9 minutes ago, fuehrio said:

This is brilliant, great advice and thank you - seems this cannabis forum becomes one of the best source of shared knowledge. Yes this is the light that was part of the whole grow tent set. So I just made the wrong thing by moving the lights closer and I hope they cope with the stress until I am back home. This type of soil was also recommended by another experienced grower. Will do some online shopping now and further hope the plants don't die in meantime so that I can update here on the success.

Good luck, any other questions just ask. ????

[Mr Meeseeks]

@tomster

 

General Hydroponics locally manufactured equivalent here: https://www.lazada.co.th/products/i4019116460-s15608049958.html

 

Local mycorrhizae powder here: https://www.lazada.co.th/products/mycorrhiza-i2384025291-s13508104047.html?

[tomster]

29 minutes ago, Mr Meeseeks said:

@tomster

 

General Hydroponics locally manufactured equivalent here: https://www.lazada.co.th/products/i4019116460-s15608049958.html

 

Local mycorrhizae powder here: https://www.lazada.co.th/products/mycorrhiza-i2384025291-s13508104047.html?

Thanks Mr Meesseks.

 

I have seen the Nutra brand and tried to get talking to them but they insisted on using Shopee chat - so gave up on that.

 

Quite why anybody would copy a 3 part nutrient when most people here use organic hot soil or coco run to waste is beyond me, but I wish them well.

 

Mycrorhizals are everywhere but the Great White Shark product has been around since the early days of my UK company, so it must be around 15-17 years old now.

 

During that time I never saw another Mycorrhiza product perform as well (although Mykos is also very good and available here), I'm sure there are others but that one really gets the plant roots firing out.

 

I also tried this one and it didn't seem to do much and they do market the same product for cannabis in another link on their account:

 

https://www.lazada.co.th/products/i2809076077-s10238236549.html

 

On that link you sent there is no breakdown of the types of Mycorrhiza that it delivers - compare that to the Great White Shark info:

 

Endomycorrhiza

Glomus aggregatum – 83 props per gram
Glomus intraradices – 83 props per gram
Glomus mosseae – 83 props per gram
Glomus etunicatum – 83 props per gram
Glomus clarum – 11 props per gram
Glomus monosporum – 11 props per gram
Paraglomus brazilianum – 11 props per gram
Glomus deserticola – 11 props per gram
Gigaspora margarita – 11 props per gram

 

Ectomycorrhiza

Pisolithus tinctorious – 187,875 propagules per gram
Rhizopogon luteolus – 5,219 props per gram
Rhizopogon fulvigleba – 5,219 props per gram
Rhizopogon villosullus – 5,219 props per gram
Rhizopogon amylopogon – 5,219 props per gram
Scleroderma citrinum – 5,219 props per gram
Scleroderma cepa – 5,219 props per gram

 

Bacteria

Azotobacter chroococcum – 525,000 CFU’s per gram
Bacillus subtilis – 525,000 CFU’s per gram
Bacillus licheniformis – 525,000 CFU’s per gram
Bacillus azotoformans – 525,000 CFU’s per gram
Bacillus megaterium – 525,000 CFU’s per gram
Bacillus coagulans – 525,000 CFU’s per gram
Bacillus pumilus – 525,000 CFU’s per gram
Bacillus amyloliquefaciens – 525,000 CFU’s per gram
Paenibacillus durum – 525,000 CFU’s per gram
Paenibacillus polymyxa – 525,000 CFU’s per gram
Saccharomyces cerevisiae – 525,000 CFU’s per gram
Pseudomonas aureofaciens – 525,000 CFU’s per gram
Pseudomonas fluorescens – 525,000 CFU’s per gram

Trichoderma koningii-187,875 CFU’s per gram
Trichoderma harzianum-125,250 CFU’s per gram

 

Not saying the local one doesn't work but I think the local producers have a way to go yet before they get to where products like Great White & Mykos have been for a very long time.

 

Cheers.

[Hook]

As soon as they break ground you should start to feed them fertilizer Nitrogen, phosphate, potash. I use 20-20-20 fertilizer during the veg state of growth Its regular garden fertilizer. After three months of 18 hours of light when I change to 12 hours putting them in the bud cycle. I change fertilizer too 8-59-8 the 59 is phosphate they need that the most when in bloom. You can flush the fertilizer out before harvest by simply given them straight water for about five waterings and your soil will be ready for your next crop. My guess is over watering the soil should have good drainage topsoil is fine to use but you have to stay on top of when and how much water you give them. And feed them with fertilizer every time you water. You may not be able to get 20-20-20 or 8-59-8 fertilizer it's what I been using anything similar or better should be fine. I have made mistakes and had a good share of them just keep at it gets easy. You have one that looks ok you're going have baby the little one good luck with the other two. 

At three months old these photos are three weeks old. 

 

long way to go yet but have been showing good progress the last three weeks.

They got too tall, so I took some string and made a hook and bent them over the secondaries get more light now. 

     

Edited August 24, 2022 by Hook
can't spell

[fuehrio]

2 hours ago, Hook said:

As soon as they break ground you should start to feed them fertilizer Nitrogen, phosphate, potash. I use 20-20-20 fertilizer during the veg state of growth Its regular garden fertilizer. After three months of 18 hours of light when I change to 12 hours putting them in the bud cycle. I change fertilizer too 8-59-8 the 59 is phosphate they need that the most when in bloom. You can flush the fertilizer out before harvest by simply given them straight water for about five waterings and your soil will be ready for your next crop. My guess is over watering the soil should have good drainage topsoil is fine to use but you have to stay on top of when and how much water you give them. And feed them with fertilizer every time you water. You may not be able to get 20-20-20 or 8-59-8 fertilizer it's what I been using anything similar or better should be fine. I have made mistakes and had a good share of them just keep at it gets easy. You have one that looks ok you're going have baby the little one good luck with the other two. 

At three months old these photos are three weeks old. 

 

long way to go yet but have been showing good progress the last three weeks.

They got too tall, so I took some string and made a hook and bent them over the secondaries get more light now. 

     

Congrats, I hope I can achieve same good looking plants once I made my learning experience. For now I have ordered peat moss, the recommended fertilizer, perlite, Mycorrhizal, PH up / down and a meter. Should arrive in 2-3 days and I think I need a lot of luck for 2 of the seedlings.