Problem with young plants

[Spirit Cloud Star Chaser]

Hey Everyone, please help young plants are dying. It started out as dark spots then started drying up and going crispy. They're in air pots with coco & perlite. I'm using advanced nutrients sensi coco grow (half strength) and superthrive. Coco is always moist but never saturated. I have attached photos for better diagnosis.. please help before it dies. Cheers everyone.

 

[CannaCountry]

You're going to need to provide your grow details...the more details the easier it will be to figure out the issue at hand.

Temps, Relative Humidity, how often do you feed, do you water with straight water at any point, do you allow the coco to dry out between feeding / watering, did you rinse and buffer your coco before you used it, are you pH'ing your feed / water and if so to what....these are all important questions to know.

 

[Hugo Phurst]

How long have you been feeding them?
IMO - A seedling doesn't need to be fed until the cotyledon starts to fade/curl

 

[3rd Monkey]

I'm going with ph but a white light pic would really help.

Looks like ph or calmag.

I don't know if there's a cal supplement in those nutes. This was not an overnight thing though. Being as they are that young, I'm guessing ph.

 

[sadanimalknight]

Looks like PH curl to me.

Having your ph off will affect the uptake of nutes.

Check PH of the runoff and let us know.

Did you buffer your coco with calmag before planting?

 

[Spirit Cloud Star Chaser]

RH 60%
Temp 27c
Feed 1 hour after lights on and 2 hour before lights out. I don't let it completely dry out as I've read it's not good for coco but it isn't soaking. I didn't rinse or buffer my coco, supposable it had already been done (Nutriefield premium coco). I do ph my nutes but my meter is playing up a bit, it's at 6 when it's working, I'll grab a new one today. I've been feeding them for about a week and a half at 0.4 ec/ 150ppm. I can take another pic when I get home.

 

[Logan Burke]

I would totally quit feeding nutrients until we pin down a cause. Besides...most seedlings sprout with what they need to grow for the first 1-2 weeks, or at least in my own experience.

*EDIT* Meant to add, I'm not sure how prevalent things such as pythium and bad microbes are in Coco, but you may consider adding beneficial microbes to help stimulate root growth in early life and throughout their entire life.

 

[Palmerrdgrower]

RH 60%
Temp 27c
Feed 1 hour after lights on and 2 hour before lights out. I don't let it completely dry out as I've read it's not good for coco but it isn't soaking. I didn't rinse or buffer my coco, supposable it had already been done (Nutriefield premium coco). I do ph my nutes but my meter is playing up a bit, it's at 6 when it's working, I'll grab a new one today. I've been feeding them for about a week and a half at 0.4 ec/ 150ppm. I can take another pic when I get home.

Is your advanced nutrients ph perfect?

 

[Logan Burke]

PH perfect isn't always PH perfect, keep in mind...it only is if you're following their nutrient program to the T.

 

[Palmerrdgrower]

PH perfect isn't always PH perfect, keep in mind...it only is if you're following their nutrient program to the T.

From what I can gather it works best between ph 4 and 8. And if you ph it manually it will cause lock out

 

[3rd Monkey]

RH 60%
Temp 27c
Feed 1 hour after lights on and 2 hour before lights out. I don't let it completely dry out as I've read it's not good for coco but it isn't soaking. I didn't rinse or buffer my coco, supposable it had already been done (Nutriefield premium coco). I do ph my nutes but my meter is playing up a bit, it's at 6 when it's working, I'll grab a new one today. I've been feeding them for about a week and a half at 0.4 ec/ 150ppm. I can take another pic when I get home.

Ph is too high. 5.5-6.0 will work, however, if you're feeding at 6.0 you are missing out on most of your micronutrients... Which is exactly what it looks like.

When your water sits, whether in a cup or medium, the ph will rise. That's called ph swing. Your runoff will be around 6.3-6.5 likely. Too high. Back her down Nute, back her down.

 

[Logan Burke]

From what I can gather it works best between ph 4 and 8. And if you ph it manually it will cause lock out

No cannabis plant will survive at a PH of below 5...the PH Perfect may be able to buffer the PH back to 5.8 if the PH falls to 4, or rises as high as 8, but it doesn't change the PH zone that nutrients are available at.

Ph is too high. 5.5-6.0 will work, however, if you're feeding at 6.0 you are missing out on most of your micronutrients... Which is exactly what it looks like.

When your water sits, whether in a cup or medium, the ph will rise. That's called ph swing. Your runoff will be around 6.3-6.5 likely. Too high. Back her down Nute, back her down.

Not true. PH does not rise when water sits. It rises for a few different reasons, most common that the plant is uptaking nutrients at a healthy rate.

 

[3rd Monkey]

No cannabis plant will survive at a PH of below 5...the PH Perfect may be able to buffer the PH back to 5.8 if the PH falls to 4, or rises as high as 8, but it doesn't change the PH zone that nutrients are available at.

Not true. PH does not rise when water sits. It rises for a few different reasons, most common that the plant is uptaking nutrients at a healthy rate.

Yes it will. Try it. The carbonic acids release and evaporate, causing a more alkaline solution.

Have OP check the runoff. That'll show you what I mean.

I'm not familiar with those nutes, so maybe that has something to do with it, but I am positive it will go alkaline. TDS of the plain water will also play a role.

 

[Logan Burke]

There shouldn't be sitting water in the first place.

 

[3rd Monkey]

There shouldn't be sitting water in the first place.

Where does it go when you water your medium?

 

[3rd Monkey]

That's why you hear a lot of folks say to let your water sit for 12hrs or so. Steadies the ph and then it fluctuates mostly from feeding. Easier to compensate for the swing... TDS dependent.

 

[Spirit Cloud Star Chaser]

Yes it is ph perfect and no I dont manually ph it because of this reason and because my pen is playing up. When I get a new ph pen tonight I'll test run off and post what it is. I have a Rec top feed set up.

 

[3rd Monkey]

Yes it is ph perfect and no I dont manually ph it because of this reason and because my pen is playing up. When I get a new ph pen tonight I'll test run off and post what it is. I have a Rec top feed set up.

What for water do you use?

 

[Spirit Cloud Star Chaser]

I use rain water from my tank

 

[3rd Monkey]

I use rain water from my tank

Should be low ppm then but you might want to check if you haven't already.