Seedlings keep stunting after sprouting! Weird behaviour

[leanshulgin]

Hi everyone, I'm new here. I've been consulting the forum for a while, trying to solve this issue on my own, but I just can't figure out what is going on, so I'm asking for your help

I'm not a new grower, I've been growing pot indoors for about five years, and I usually get good results. But the last attempts have been a complete failure!!! The last "good" grow that I was able to pull out was about a year ago, 5 super skunks. Grow went well but leaves started to turn yellow and fall too soon during flowering stage. And then some buds developed gray mold (botrytis?). I managed to save most of the crop, but since then I haven't been able to go from seed to veg successfully, I have never managed to get after the first pair of true leaves again

I had some seedlings damping off last year, and then I had to stop because of the summer temperatures (I live in Argentina). Last month, I tried to start again with some seeds I had, but after sprouting and emerging, the first pair of true leaves get curled down and never develop. I though it was the botrytis or some other fungus, so I cleaned everything in the grow room, and even all the house with bleach. Then, started again with 6 white widow x critical, and treated each substrate with different fungicides before emergency: 3 with amistar xtra (azoxystrobin + cyproconazole), 1 with trichoderma (the organic option) and now I added 2 more treated with a fungicide i've bought at the garden shop (carbendazim), wich haven't emerged yet, I think they will in one or two days.

So, here is the setup:

_I'm using a commercial substrate called growmix multipro, wich I've been using in the last grows (has peat, perlite, dolomite for adjusted pH to 5.8, 80-90% organic matter).

_I'm using tap water wich I let to rest for a day before using it to remove chlorine (pH=6)

_I'm keeping the soil moist until seedlings emerge, then I let it dry before I add more water. I'm checking the weight of the pots in order to know when they are dry.

_Plants are in little cups of 250ml

_Light: Metal Halide 250w 24hs

_Temp and humidity : average 28-30ºC (82-86F) and 30%RH (the temp is a little high and moisture a little low)

Symptoms:

_Seeds sprout normally and cotyledons emerge from the soil about 4 days after planting the seed.

_Cotyledons start looking downwards and take abut 2 days to turn and start looking up

_Cotyledons look darker than normal, and have some subtle purple hue

_Both cotyledons and leaves curl downwards.

_Seedlings do not dye, the just grow very very very slow. In the ones I've tryed before these showed a second par of leaves after 2 weeks, but plants were very small, not the normal size.

_ The fungicide amistar xtra and the trichodermas seem to have no effect. Waiting to see what happens with the carbendazim, but i'm starting to doubt this is caused by fungus.

_The same thing happened with different strains: super skunk, ak47, white widdow, some unknown sativas and these white widow x critical.


I have 50 seeds of this strain to try different stuff, of wich I've used the 6 that I have mentioned before. I want to solve this mystery once and for all, so I'm open to suggestions and try different approaches. I'm so frustrated right now

Maybe the soil is too "hot"? should I try a different medium?

I put some pictures for you to see the problem. The plants that you see have 7 days from seed, 3 days since emergency.

Hope you can help me!!! I just want to be able to grow again, i'm thinking of giving up

 

[wiley420]

R u reusing the soil ?


Sent from my iPhone using 420 Magazine Mobile App

 

[Lansky]

The problem could come from a few things:

1- Tap water: Maybe there is Chloramine in your water which would be lethal for your soil microbial metabolism. Chloramine does not evaporate. So check with your water company and look for some kind of filter to remove the Chloramine.
2- Temp and Humidity are off, too hot and not humid enough. I keep mine 77F and 65%.
3- Water method, Although dry/wet is the right techniques, I feel it must be applied only after the seedling has establish a root system, maybe 10 to 14 days. Until then, the seedling is getting its water from the environment, so I keep mine moist at all time, I mist clean water once a day on the top soil. given your low humidity, your seedling is thirsty.
4- The light 24/24 might be an issue, first of 250W MH is a bit overkill. I use LED COB CREE so I could not compare but to give an idea, I put them under gradual increase, at 1 week, they receive each about 25 W. However my lights are much closer than yours to keep my plant from stretching too much and keep them warm.
5- Might be your soil that isn't cooked properly before planting. I am not familiar with your mix, but I believe you should use some EWC and rooting agent.
6- I see you have a big fan above as well, I keep mine under the level of my seedling to avoid unnecessary trauma but keep the air moving, then when the plant is grown a bit more I put my fans above to stimulate stem strength.

Just my two bits, I hope this help.

 

[leanshulgin]

Thanks a lot for the input guys.

So here is what I did.

_the two seeds that hadn't emerged yet have already sprouted, so I changed them to the common potting soil that I used to use when I started growing. It has low organic matter content and neutral pH, so over-fertilization shouldn't be a problem

_ I also re-potted one of the seedlings to the same soil mixture to see what happens

_ I bought some purified (not mineral) water, so I'm not using tap water anymore.

_it is true that 250w MH is a bit too much, but I've always had amazing growth in veg with it, so I'm keeping it, but I've moved it higher in order to lower the temp where the pots are, so now it is about 27C (80F) That is as low as I can get if for now, but is the temperature that I usually have with the lights on. Autumn is coming so I'm expecting lower temps in the next few weeks.

_Added a recipient with water under the light and RH increased to 40% so it's better now.

_I had the lights on 24hs because I was scared of fungus and wanted the soil to dry quickly. Now that I know that is not the problem (at least this time) I'm going back to 18/6.

So, I hope my babies like this changes and start growing normally. I'll let you know how things are going in a couple of days

See ya!

 

[leanshulgin]

nope, I never do

 

[Lansky]

I am also thinking russet mites, they love warmer and drier environment, they come from the earth, so if you soil was contaminated... oh boy. Russet mites are so small, microscopic should I say, you won't see them, only their eggs if you pay attention very CLOSELY. They are the cause of many unexplained death in new growth. But in general, the plant is already a few inches tall for this to happen. I've never heard of seedlings attacked by russet mites....

 

[leanshulgin]

UPDATE: Problem is in the roots!

Ok, those up there are dead, never grew bigger than what has been shown.
Planted new ones, changed the soil form peat moss based to the common potting soil i used when I started growing pot. These started ok, looking healthy, but after the first pair of leaves again began to grow slowly and weak, they are like miniatures. So I took a look at the root system and this is what i've found. Very poor root developing, poor branching, no white "hairs" in most of the roots, they are brown and thin.
I've been using fungicide and letting the soild dry but it doesn't help.

I think it may be fusarium??? pythium?, if that is the case im dead my grower days are over...

Here are some pics...

This one looks healthy...

 

[Pseu65]

I'm no expert and I have my own set of problems with my first real attempt at this, however, I do have a lot of experience with plants in general. If you're interested, here's my take. They are thirsty, I strongly believe that they need more water than what you are providing. They are quite young and small to be letting them fully dry out between waterings. You need to get the roots to establish before you go to that.

I suggest, just for shits and giggles, that you NOT let the soil completely dry out yet. Even if it's just a splash of water you need to keep that soil moist so they can get a good hold. You can either spray the soil near the base of the plant until it's damp or give them a little sip. You don't want the soil sopping wet but you certainly don't want to let them dry out completely until they have more leaves and a good root structure. So why not take one plant, check it daily and make sure the soil basically remains "moist" untill they have a few more leaves. Also, no nutrients right now, there's no need. What do you have to lose?

 

[Planter420]

Would also suggest giving them roots just a tad more space .

 

[Houdini420]

I am also thinking russet mites, they love warmer and drier environment, they come from the earth, so if you soil was contaminated... oh boy. Russet mites are so small, microscopic should I say, you won't see them, only their eggs if you pay attention very CLOSELY. They are the cause of many unexplained death in new growth. But in general, the plant is already a few inches tall for this to happen. I've never heard of seedlings attacked by russet mites....

I'm dealing with this issue after having russet mites. Repainted, and rebuild, just to have them attack my sprouts again and again. I'm about to heat treat my grow area but they are monsters to get rid of!!!!

 

[Houdini420]

Thanks a lot for the input guys.

So here is what I did.

_the two seeds that hadn't emerged yet have already sprouted, so I changed them to the common potting soil that I used to use when I started growing. It has low organic matter content and neutral pH, so over-fertilization shouldn't be a problem

_ I also re-potted one of the seedlings to the same soil mixture to see what happens

_ I bought some purified (not mineral) water, so I'm not using tap water anymore.

_it is true that 250w MH is a bit too much, but I've always had amazing growth in veg with it, so I'm keeping it, but I've moved it higher in order to lower the temp where the pots are, so now it is about 27C (80F) That is as low as I can get if for now, but is the temperature that I usually have with the lights on. Autumn is coming so I'm expecting lower temps in the next few weeks.

_Added a recipient with water under the light and RH increased to 40% so it's better now.

_I had the lights on 24hs because I was scared of fungus and wanted the soil to dry quickly. Now that I know that is not the problem (at least this time) I'm going back to 18/6.

So, I hope my babies like this changes and start growing normally. I'll let you know how things are going in a couple of days

See ya!

Ii really think your issue is Russet mites. Replanting won't help, in fact it'll make it worse as you spread them more and more. I hope you fixed and sterilized everything and if you got rid of them, please tell me your secret. been dealing with these monsters for 2 months now. Can't get another grow off the ground.

 

[013]

Hey Houdin,

Welcome to 420! That’s an old post from 2017. But if you are having same problem then oven cooking your soil at 250 for 30 minutes might be an option to consider, as well as sterilizing all of your containers, tools and tent with a bleach water solution. One of our sponsors is SNS they make a full line up of organic pest killing sprays and concentrates.

hopefully a few other people will jump in too

 

[NuttyProfessor]

lol grave digging i do it too,

 

[013]

I know - right? Ive jumped on so many only to find out it’s an old post!

 

[Nunyabiz]

That "soil" is literally just mud.
Lack of oxygen was the problem

 

[NuttyProfessor]

easy done my friend

I know - right? Ive jumped on so many only to find out it’s an old post!

 

[QA1142]

Hi everyone, I'm new here. I've been consulting the forum for a while, trying to solve this issue on my own, but I just can't figure out what is going on, so I'm asking for your help

I'm not a new grower, I've been growing pot indoors for about five years, and I usually get good results. But the last attempts have been a complete failure!!! The last "good" grow that I was able to pull out was about a year ago, 5 super skunks. Grow went well but leaves started to turn yellow and fall too soon during flowering stage. And then some buds developed gray mold (botrytis?). I managed to save most of the crop, but since then I haven't been able to go from seed to veg successfully, I have never managed to get after the first pair of true leaves again

I had some seedlings damping off last year, and then I had to stop because of the summer temperatures (I live in Argentina). Last month, I tried to start again with some seeds I had, but after sprouting and emerging, the first pair of true leaves get curled down and never develop. I though it was the botrytis or some other fungus, so I cleaned everything in the grow room, and even all the house with bleach. Then, started again with 6 white widow x critical, and treated each substrate with different fungicides before emergency: 3 with amistar xtra (azoxystrobin + cyproconazole), 1 with trichoderma (the organic option) and now I added 2 more treated with a fungicide i've bought at the garden shop (carbendazim), wich haven't emerged yet, I think they will in one or two days.

So, here is the setup:

_I'm using a commercial substrate called growmix multipro, wich I've been using in the last grows (has peat, perlite, dolomite for adjusted pH to 5.8, 80-90% organic matter).

_I'm using tap water wich I let to rest for a day before using it to remove chlorine (pH=6)

_I'm keeping the soil moist until seedlings emerge, then I let it dry before I add more water. I'm checking the weight of the pots in order to know when they are dry.

_Plants are in little cups of 250ml

_Light: Metal Halide 250w 24hs

_Temp and humidity : average 28-30ºC (82-86F) and 30%RH (the temp is a little high and moisture a little low)

Symptoms:

_Seeds sprout normally and cotyledons emerge from the soil about 4 days after planting the seed.

_Cotyledons start looking downwards and take abut 2 days to turn and start looking up

_Cotyledons look darker than normal, and have some subtle purple hue

_Both cotyledons and leaves curl downwards.

_Seedlings do not dye, the just grow very very very slow. In the ones I've tryed before these showed a second par of leaves after 2 weeks, but plants were very small, not the normal size.

_ The fungicide amistar xtra and the trichodermas seem to have no effect. Waiting to see what happens with the carbendazim, but i'm starting to doubt this is caused by fungus.

_The same thing happened with different strains: super skunk, ak47, white widdow, some unknown sativas and these white widow x critical.


I have 50 seeds of this strain to try different stuff, of wich I've used the 6 that I have mentioned before. I want to solve this mystery once and for all, so I'm open to suggestions and try different approaches. I'm so frustrated right now

Maybe the soil is too "hot"? should I try a different medium?

I put some pictures for you to see the problem. The plants that you see have 7 days from seed, 3 days since emergency.

Hope you can help me!!! I just want to be able to grow again, i'm thinking of giving up

Humm, no issues with seeds for me. I start in a paper towel, move to plug then soil once tap root is there. I put clear solo cup over seed till it is above ground. Running 600w led. If you cannot get RH up, use solo cup and get seed/sprouts RH up.