COCO COIR Problems growing in coco

[drumster361]

Hi all ... Newbie here with a problem!

I have recently been having trouble growing in soil and have had a couple of plants die in the first 2-3 weeks of growth for reasons I'm really not sure of. In the first week, the seedlings shot up faster than expected and all was looking hopeful but by the second week the leaves had yellow tips and by the third, they were almost dead. I did lots of research but couldn't find anything that looked similar to this problem and didn't really provide anything conclusive. That being said; most of the relatable solutions pointed to the water retention of the soil and the PH.

For me, this is where it got confusing... after realising the first 2 plants were dying, I started to germinate and plant 2 more seeds, except this time I used coco coir with a 20% perlite mix that I got from Amazon because I've heard it's almost impossible to overwater and more forgiving than soil.

For fertilizer, I bought have some Advanced Nutrients: Big-Bud, Cal-Mag and had some general Tomato food nutrients.
(Slightly embarrassing to admit but I've heard that tomato food has all the basic nutrients cannabis needs and I already had some from my last grow, which it worked great for! As I'm trying coco for the first time, I'm thinking that I'm going to need ferts that are far more specific than tomato food, for the plants to thrive properly?)

Anyway; the new plants in the coco have been alive for just over a week now. They both looked healthy and really green (If a little too light) and I thought they were doing better than the previous ones I had planted in soil until, over the past couple days, I've seen almost no growth from either of them. On a more alarming note, one of them has developed white spots over the past 24 hours and has now started to shrivel up!! The other has remained quite light green with minimal growth.
I was almost certain it was the calcium/magnesium deficiency caused by coco that I had been reading about and so earlier today I gave them some feed while watering, making sure to add a healthy dose of the calcium/magnesium supplement to try to kickstart it back up.

Long story short; one of the plants seems to be responding well and the dying one is still dying. Could the dying plant be diseased? have I done something to mess this up? and if so then why is just one plant dying like this? I've heard using un-branded products can be bad but would it really destroy just one plant this badly??

I'm pretty new to the game so go easy on me! I had basically none of the problems I am experiencing now, during my last grow; which was a great success for a first time grow!


Here is exactly what I'm using


The seeds:
(Focusing on just the new ones planted in coco)

1 x Critical (Auto / Fem )

1 x Lemon Shining Silver Haze (Auto / Fem)


Equipment:

1x 300w Marshydro LED grow light
1x Humidifier (Try to keep the humidity around 60-80%)
1x Fan
1x Thermostat (reads humidity too)
1x Litmus paper / PH tester

Fertiliser:
(Only just started so haven't really worked out a specific amount or routine, just following the guidelines I read online / on the bottle!)

Advanced Nutrients: Big Bug

Levington: Tomorite (Local garden centre tomato food)

Plant Magic - Mange-Cal+



Any advice is dearly appreciated as this is something I really can't wrap my head around.

It's bedtime where I am currently so I'll put these plants to rest and check if there is improvements in the morning but I can't say I'm overly confident there will be.

Thanks for reading this long-ass post and I hope you have a great day!

[Mr.furley]

Your plants are to young to be feeding and it looks like nutrient burn.

you can overwatering coco, you need to water then let the pot dry out or you're depriving them roots of oxygen when you keep the wet all the time.

[Mr.furley]

I'm sorry drumster361 my mistake
Baking soda or sodium bicarbonate is used to raise pH, its lemon juice or vinegar you want..

I should have had a cup of coffee first.

[drumster361]

Okay cool, thanks for the info! that would have been bad haha.

[drumster361]

Mr.furley I bow down to you sir. I've not watered these girls in over 2 days now.... and they've sprung back to life and are now starting to grow again!! I think it was down to overwatering as you said plus maybe calcium/magnesium deficiencies from coco?? but either way, I'll post pics below to get your opinion. Planning on watering today but the coco isn't fully dry yet...

[drumster361]

Update: Not watered in 2 days and life has returned! Planning to water soon at 6.2PH as suggested w/ no feed. Not sure if today is still too early but the plants are doing very well currently so I'm pretty happy!

[Mr.furley]

I'd still let them dry out another day of two, that is a big pot for a little plant with no perlite. As far as calmag goes you will need it but once again the plants are pretty young so careful with nutrient at this point.
I don't feed my plants much for the first two weeks, just rapid root or liquid kelp.

Going forward and when you transplant, you are going to need more Perlite in your pots, it should be a mix of 70% coco to 30% perlite, this will help with drainage and air flow to dry your roots out faster.

There are two ways to overwatering coco
1) too frequently. ( there is a system but that another topic)
2) too much water for a small plant in a large pot.
Runoff is very important in a coco grow but not at that plants age.

https://www.growweedeasy.com/how-to-water-a-seedling-in-a-big-pot

Keep us posted

[drumster361]

Yeah, I'll leave them for another day I think! the coco pre-mix I bought came as 80%coco to 20%perlite. I agree though, It doesn't look like there's any perlite in there at all. I think I made another mistake buying coco from Amazon! I'll buy something a bit more high-end next time I think.

As for the pot, It is slightly on the large side and I didn't think about its size too much. I'll probably transplant 1 or 2 more times before they're in their final pots. Will check out that link you sent as well. Thanks again for the info!

[Tersky]

personally i would do 30-40% perlite as coco is not that forgiving really. Its the perlite that allows for oxygen and drainage. Also pH matters MUCH more in coco than soil. Soil usually has organic "buffers" that can assist the plant in nutrient uptake where is coco is inert and has no such "buffers" so the ph of your water going in has to be monitored more closely. I personally use coco and like it but it takes a little getting used to the nuances of coco growing (charging the coco before hand, using cal mag, ph correctly ect).

[Tersky]

Good catch Mr.furley i had forgotten that part. Yes some coco's are precharged. I dont have experience with the precharged stuff but i do buy the premixed perlite and coco. Im worried (probably unjustifiably but whatever) that the pretreated coco will have more issues with pests due to the microbes and possibly being set on a dock for months. I personally feel more comfortable doing my own wash and buffer, cause i know that if anything goes wrong, it was something i did and i can rectify the issue. But im curious on other's take on precharged coco.

[Mr.furley]

Tersky
it goes even deeper than that! Check where the coco is sourced from, Inland or Coastal? Coastline sourced coconut will carry a higher salt content and will need to be washed more so than Inland coconuts.

I have used both kinds pre buffered and a brick, I have no preference.

[drumster361]

Good point. I'll make sure to keep an eye out for the finer details when buying next time. For now; the plants have basically made a full recovery and I'm hoping they'll continue to grow nicely now that I understand coco a little better haha

Thanks again guys, big help!