How do I start an autoflower grow in solo cups with coco?

Hey guys,

I just can't get seedlings to grow nicely in solo cups with coco/perlite, and Canna A+B. It just never works, I kill one seedling after another with severe overwatering symptoms. Droopy leaves, brown spots everywhere, seedlings turning pale yellow, just typical for "too much water".

What am I doing wrong here? I put holes in the bottom of the cups (lots of them), fill them with Canna Coco Professional Plus and 30% perlite, then prewater every solocup until some runoff with a light nutrient solution of around 0.8EC (RO water + 0.3EC Calmag + 0.7EC Canna A+B, watered down to 0.8, PH 5.. I then plant the germinated seeds, humidity dome on top, sprout 1-2 days later, and then they seem fine for 1-2 days. Afterwards, growth slows down extremely, they turn a pale green, droop down severely. I tried watering every day til runoff, in another attempt I tried letting them dry out, but they just don't grow NEARLY as quick as I'm used to with Biobizz or other substrates. By day 7 after sprout I usually have the third set of leaves growing outwards, with coco I usually still have the first set of leaves, with the second set just slowly pointing out of the stem. Just INSANELY slow growth, especially bad for autoflowers.

My temps are alright, around 74-77°F, 60-65% humidity, I got air circulation, air exchange, everything is running perfectly fine. I don't know why my seeds are always severely stunted in coco, and why they just turn to trash each and every time. The worst guide that killed my seeds the quickest was the cocoforcannabis guide, I'll never touch that website again. Does anyone have a rough guide on how they start their seedlings in coco and solocups?

Shnoobs58 said:

Canna Coco Professional Plus and 30% perlite, then prewater every solocup until some runoff with a light nutrient solution of around 0.8EC (RO water + 0.3EC Calmag + 0.7EC Canna A+B, watered down to 0.8, PH 5..

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0.8 EC seems strong out of the gate. I start at 0.4 EC. What is the pH? The second digit is a smiley face. You could do something like 5.8 start to finish, but I'll do around 6.2 for the first two weeks, as calcium is more available in that range, and then lower it to 5.8 in week three.

When are you removing the humidity dome?

Your temps are also on the low side. If you're growing with LED, the sweet spot is around 82F. 74-77 isn't going to kill it, but it will grow slower. That temp range is better for HPS lighting and not LED.

So what light are you using and the distance to the seedlings and its dim setting? Or, if you know, what is the PPFD at canopy level?

Shnoobs58 said:

The worst guide that killed my seeds the quickest was the cocoforcannabis guide, I'll never touch that website again.

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Dr Coco has the best information about growing in coco. I can assure you that you were doing something wrong, as I, and many others here, have been using his practices and feed charts for years with great success. The only thing that I don't do that he recommends is I don't use jiffy pellets - I just start right in coco.

Like, everything and every step needs to be inspected. Something like how someone packs the coco into the solo cup could be wrong. For example, packing it down tightly would not give the seedling enough oxygen, or something like not sifting out much of the coco peat (coco particles that are dusty or the size of coffee grounds) could cause impaction issues. Both would cause overwatering symptoms.

You could start a new run in this thread and post all info with pics as you go and we can help.

ec121 said:

0.8 EC seems strong out of the gate. I start at 0.4 EC. What is the pH? The second digit is a smiley face. You could do something like 5.8 start to finish, but I'll do around 6.2 for the first two weeks, as calcium is more available in that range, and then lower it to 5.8 in week three.

When are you removing the humidity dome?

Your temps are also on the low side. If you're growing with LED, the sweet spot is around 82F. 74-77 isn't going to kill it, but it will grow slower. That temp range is better for HPS lighting and not LED.

So what light are you using and the distance to the seedlings and its dim setting? Or, if you know, what is the PPFD at canopy level?




Dr Coco has the best information about growing in coco. I can assure you that you were doing something wrong, as I, and many others here, have been using his practices and feed charts for years with great success. The only thing that I don't do that he recommends is I don't use jiffy pellets - I just start right in coco.

Like, everything and every step needs to be inspected. Something like how someone packs the coco into the solo cup could be wrong. For example, packing it down tightly would not give the seedling enough oxygen, or something like not sifting out much of the coco peat (coco particles that are dusty or the size of coffee grounds) could cause impaction issues. Both would cause overwatering symptoms.

You could start a new run in this thread and post all info with pics as you go and we can help.

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First of all - Thanks for the big answer!

0.8EC was my latest attempt, the one before this started with 0.4EC, with a PH of 5.8 in both attempts. I imagine the smiley face was a typing error or something, whoops.

I remove the humidity dome as soon as the cotyledons open fully, as recommended by pretty much everyone unless they're clones, which I have never used.

Temps are on the low side, yeah, I sadly can't do anything about this. I have no AC, outside temps are rather cold currently, I have to fully rely on the weather. Heating a whole room for one tent is rather expensive in my country, so I have to rely on ambient temps inside the house & the light giving off some heat.

My light is a MarsHydro FC6500-EVO, dimming is at around 40%, and it's currently pretty damn high, don't know the exact height though. I only know that I'm currently running a DLI of around 18, with 230PPFD. This was measured with a physical PAR/PPFPD reader and the Photone app, which are both +-20PPFD in range.

Dr Coco, yeah, I tried following his guide twice & in both attempts my plants just drooped down severely, 100% overwatering issues, they never stopped drooping unless I let them dry out fully, which in return caused burns on them. It was straight up a circle of hell.

I usually fill my solo cups just with the coco perlite mixture, and that's it. No compacting, no heavy watering with a watering can, I use syringes to water small solocups, the 30ml syringes, just sprinkling water on the substrate. I fill it up, prewater it slowly, then poke a hole inside there, add the seed, sprinkle some coco on top, done. No pressing or anything.

About the coco - Because you mentioned it, I just sifted my coco. I use Canna Coco Professional Plus, and 90% of the substrate went through the sifter. There was nothing left, besides a few strands of coco fiber, and woody hard chips. I even took some images for you. Please ignore the perlite, it was some old substrate I had left in the saucer.




I sifted 1 handful of substrate, and had around 1/10th of this rough stuff left, 90% of the coco went through the sifter & was just powder, similar to the coffee grounds you've mentioned which you can see in the second omage (As mentioned, ignore the perlite, it was already in the pot I sifted it into!). I've done tons of research, and pretty much each and everyone loves Canna Coco the most, which is why I chose this one

Shnoobs58 said:

Dr Coco, yeah, I tried following his guide twice & in both attempts my plants just drooped down severely, 100% overwatering issues, they never stopped drooping unless I let them dry out fully, which in return caused burns on them. It was straight up a circle of hell.

I usually fill my solo cups just with the coco perlite mixture, and that's it. No compacting, no heavy watering with a watering can, I use syringes to water small solocups, the 30ml syringes, just sprinkling water on the substrate. I fill it up, prewater it slowly, then poke a hole inside there, add the seed, sprinkle some coco on top, done. No pressing or anything.

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Coco is essentially hydroponic. Overwatering isn't from too much water; it's from too little oxygen. In DWC, the roots are 100% in water 100% of the time. It's the bubbling of the water that allows oxygen to roots. In coco, it's the fibrous coco and/or perlite that allows oxygen to the roots.

If drying the substrate made the seedling fry, then that suggests that the EC of your substrate is too high. Once it begins to dry, that spikes the EC even higher, resulting in the seedling frying (assuming by "drying out" you mean around 70% dry and not 100% ).

My final step with my buffered coco is to rinse it down with some 0.4 nutrient feed until the runoff comes out at 0.4 EC before planting the taproot a day or two after the rinse with nutrient feed. Mist the top, put a dome over it, and once it pops up from the media, I'm feeding it at lights on everyday.

I'm feeding by fertigating slowly and evenly, until a healthy amount of runoff comes out. This ensures the EC stays consistent from day to day as much as possible. If you're feeding with a syringe and no runoff is coming out, then the EC is going to start to spike because the salts are not being regularly pushed out.

It's also possible that the EC of your coco right out of the gate is too high. Since you're using prebuffered coco, you should hit it with 0.4 feed until the runoff is 0.4 to ensure it's not too high.

Also, you might want to think about using a 50/50 mix of coco/perlite. I don't use perlite anymore and grow in 100% coco (which requires a little finesse during the first 5 or so days) in 1g pots, but since you're having oxygen problems, a 50/50 coco/perlite mix will fix it.

Finally, you should measure your runoff EC, especially if you've been experiencing problems. If you were feeding at 0.8 EC and the first bit of runoff came out at 2.3 EC, then the cause of your problems is obvious and is very easy to fix.

I prefer to start in cell trays or peat plugs, using well rinsed coco or coco/perlite. If you're wondering whether you should rinse your coir, hydrate some and test the runoff.

I feed at an EC of 1.6 starting from the first watering after they sprout, allowing the medium to dry out sufficiently between waterings until the roots get established. Give this a try with tomato seeds if you need more fodder to iron out your method.

I'd make sure your holes are big enough in your solo cup as well, but it sounds like you didn't rinse your coir and aren't watering to runoff, which I'd imagine is your problem.

So I've done a trial attempt, and mixed a tiny fresh batch of my usual canna coco/perlite substrate. Filled it into one of my solo cups, and measured the runoff. I used my seedling solution of 0.548EC, and watered the cup til runoff. At first, some dusty water came out, around 10ml, and then clear nutrient water. It was measured at 0.556EC.

Here is what my solocups look like:



The problem is - My seeds look fine for the first 1-2 days, but then they stop growing. It's been 8 days now since my seeds sprouted, and they still haven't shown any growth on the second set of leaves, hasn't changed for around 5 days now. No roots showing up on the bottom of the cups, nothing. After I watered til runoff (which was a lot for these cups, around 100ml of feed per cup until I had tiny runoff), they just started drooping down and never recovered from stunted growth. I feel like I'm cursed with coco or something, as my seeds usually grew twice as fast as the average seed, just because I took good care of them in other substrates.

This is what my 7 day old seedlings normally look like after sprout WITHOUT coco, all the same size, healthy, praying, just perfect:



And this is what they look like right now in coco, 8 days old, they're all exactly this size, so it's user error, not genetics:



I think you might understand my disappointment, because I'm used to the growth in the first image here. And now I switched to coco, with the average opinion being that it's a bit faster than soil / other substrates, and my seeds keep being tiny and droopy all the time. I just don't understand what kinda mistake I'm doing here. Watering to runoff makes them extremely droopy, letting them dry out makes them act funky too.

Make sure you rinse and buffer your coco first.
Use a 50/50 coco/perlite mix.
Saturate the coco with a light nute solution, then plant the seed.
Ditch the dome........not necessary.
After about 3 days from sprout, start feeding daily to run off.
Never use plain water.
They should look like this at one week

And this at two weeks.

Shnoobs58 said:

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Plant looks hungry, I'd up the feed next watering.

pH 5.8-6.2, EC ~1.6, let it dry out between waterings until roots are established. That's what I'd try.

There's one thing that confuses me a lot - I often see coco that seems "rough", while my coco seems like 90% dust, 9% rough little pellets, and 1% of some fiber. Is this maybe why I can't follow the usual "daily fertigation" advice? I use Canna Coco Professional Plus, and it's pretty much dust as you can see in the images I posted further up.

I also couldn't resist and wanted to check the root growth of one of the seedlings, so I turned the cup over and carefully slipped it out of the solocup, no damage done. The roots were fine, not a lot of them though. Some on the bottom, some on the sides, 40% of what I would expect at this age. But I did notice that 50% of the coco on the bottom was dripping wet, not just moist, as if it kept A LOT of water. It was a literal brick of water, coco, and perlite on the bottom. I thought coco always has good oxygen retention, so I don't know why my coco just straight up turns into a brick, even while only watering careful with a syringe and lots of time. I also made sure there's MORE than enough runoff holes on the bottom, way more than I usually see, yet the water just collects heavily on the bottom.

So many people recommend Canna Coco Professional Plus, but I feel like I might be doing something wrong here?

Shnoobs58 said:

There's one thing that confuses me a lot - I often see coco that seems "rough", while my coco seems like 90% dust, 9% rough little pellets, and 1% of some fiber. Is this maybe why I can't follow the usual "daily fertigation" advice? I use Canna Coco Professional Plus, and it's pretty much dust as you can see in the images I posted further up.

I also couldn't resist and wanted to check the root growth of one of the seedlings, so I turned the cup over and carefully slipped it out of the solocup, no damage done. The roots were fine, not a lot of them though. Some on the bottom, some on the sides, 40% of what I would expect at this age. But I did notice that 50% of the coco on the bottom was dripping wet, not just moist, as if it kept A LOT of water. It was a literal brick of water, coco, and perlite on the bottom. I thought coco always has good oxygen retention, so I don't know why my coco just straight up turns into a brick, even while only watering careful with a syringe and lots of time. I also made sure there's MORE than enough runoff holes on the bottom, way more than I usually see, yet the water just collects heavily on the bottom.

So many people recommend Canna Coco Professional Plus, but I feel like I might be doing something wrong here?

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I ran Coco Pro Plus for years. I only stopped when my Grow Store couldn't get it for awhile. Now I run Botanicare's Aeration mix and don't have to mix it with perlite as I did my Canna Coco. So go ahead and add some perlite to your Canna Coco if you feel you need more drainage.

I use nutrifield dry bricks. It has a lot of dust but nothing like you describe. I use 1/8” mesh strainer too which is waay bigger than your sifter. Idk mileage can vary idk how consistent it is but I havent looked for a new brand since. Done few grows with it.

Idk how people get poor growth at this phase, Im a newer grower too but never had these issues if the seed was healthy.

I wouldnt give up, this the only method I was able to succeed in. I fed 1.2 ec from seed once a day to runoff. I wouldnt even do cups no more, I switched from 3 gal to 1 gal. Id just plant it right in the 1 gal.

The weight of cup should be your clue to watering time.
Until three set,s of leaves there should be no nutrients only straight water,make sure it is correct Ph.
At the start wet coco with plain water wait till run off stops then put seed in.
I have done this for a few years and have lost a couple with seedling dying with dampening off.

A place a small lucky stone in one cup and put the seeded cup inside. Precious little for seedlings for sure,
good luck Shnoobs

medidedicated said:

I use nutrifield dry bricks. It has a lot of dust but nothing like you describe. I use 1/8” mesh strainer too which is waay bigger than your sifter. Idk mileage can vary idk how consistent it is but I havent looked for a new brand since. Done few grows with it.

Idk how people get poor growth at this phase, Im a newer grower too but never had these issues if the seed was healthy.

I wouldnt give up, this the only method I was able to succeed in. I fed 1.2 ec from seed once a day to runoff. I wouldnt even do cups no more, I switched from 3 gal to 1 gal. Id just plant it right in the 1 gal.

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Trust me, I am confused as hell too. Especially because my seeds usually do thrive insanely well in my conditions. I wanted to move away from handwatering and organics, so I bought autopots, coco, canna nutrients, everything, I was 100% ready to go.

It's been over 2 months now and I wasn't able to use my autopots.. once. Because I wasn't able to come that far yet, all my seeds in coco just stop growing after a few days. It's laughably stupid and depressing for me. I followed several different guides, drying out, daily fertigations, they all stop growing quickly after the first set of true leaves slowly show up, they all become droopy, with a big lack of root growth too.

Shnoobs58 said:

Trust me, I am confused as hell too. Especially because my seeds usually do thrive insanely well in my conditions. I wanted to move away from handwatering and organics, so I bought autopots, coco, canna nutrients, everything, I was 100% ready to go.

It's been over 2 months now and I wasn't able to use my autopots.. once. Because I wasn't able to come that far yet, all my seeds in coco just stop growing after a few days. It's laughably stupid and depressing for me. I followed several different guides, drying out, daily fertigations, they all stop growing quickly after the first set of true leaves slowly show up, they all become droopy, with a big lack of root growth too.

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Dang I wish I could do soil, no fears of floods in the home. That sucks, I struggle as a new grower too but I just dont know what it is. Was more suggesting a brand of coco. Hope you figure it out!

Water source maybe? Id plant it in coco that looks like what you sifted and ended up with with some pearlite. I just use maxibloom. I do 1.8ec now and wouldnt hesitate to do seeds in it. I did clones in it. So ec I dont think is it. No calmag just maxi bloom.

I use one of two methods. I have started my seeds in root Riot plugs and then let those go until there are Roots poking out all over the plugs and just water those with plain water until it gets to that point. Once it gets the second and third set of leaves I will mix up a very mild nutrient solution for them. Once the roots are exposed and growing out of the plug, I put it into a cup of coco or the pot that it's going to grow in. And then daily fertigation with a nutrient solution starts.

The other method I have used a couple times now successfully is starting a seed in coco and treating it almost exactly like soil until it becomes established. The only difference is that I will mix up a nutrient solution that is very very weak. Like 100 PPM or less. Just enough so there's something in the coco. I keep them damp but not waterlogged. That said, I do rinse and buffer my coco with ph'd solution. I have also gotten rid of perlite and that is one of the best decisions I have ever made. That stuff sucks. I hate it. Then, once you see roots coming out of the bottom of whatever container you are using you can transplant that right into your final pots and start your daily fertigation and slowly step up the nutrient solution.

Yea youre not the only one I see here and there people just have that happen but youve checked a lot of boxes out so thats weird. Ph meter good? Bacteria out break, are roots brown?

I use pool shock and feed twice a day from start for high dissolved oxygen and keep plant/reservoir sterile.

I like when say mileage varies I couldnt succeed in soil even with roll it ups help I tried everyones help. I actually had poor results at first until I followed Mick Foster’s suggestion up until my mileage varied in later phases growth.

I was allowing dry back feeding plain water then boom soon as I fed daily it grew overnight.

medidedicated said:

Yea youre not the only one I see here and there people just have that happen but youve checked a lot of boxes out so thats weird. Ph meter good? Bacteria out break, are roots brown?

I use pool shock and feed twice a day from start for high dissolved oxygen and keep plant/reservoir sterile.

I like when say mileage varies I couldnt succeed in soil even with roll it ups help I tried everyones help. I actually had poor results at first until I followed Mick Foster’s suggestion up until my mileage varied in later phases growth.

I was allowing dry back feeding plain water then boom soon as I fed daily it grew overnight.

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My PH probe is a brand new Apera PH60, fully calibrated and always washed with RO water, dried, then stored in KCL solution in every use. It's a huge hassle, but I want 100% precision, it's worth it. Also 3-point calibrated weekly, but it's rarely off at all.

EC probe is also brand-new, and fully calibrated. A 1318EC solution gets read at 1315EC, which is 100% fine to me.

Roots look fine, I forgot adding the image when I pulled one of the seedlings out of the cup. I know, not recommended, but I have done this uncountable times in organic soil and it never hurt anything. This is 8 days of root growth, +2 days of germination, so almost 10 days of root growth. This is usually what 4 days of root growth looks like for me, which is rather confusing after hearing so much positive feedback about coco. But it's not the coco, I am doing something wrong here.



Water - I don't know. It's fresh RO water, which I usually store no longer than 4-5 days. It has an average EC of 0.04, which is fine for RO I imagine. Then 0.3EC of Canna Calmag, and 0.7EC of Canna A+B, water down to correct EC, fix PH, done.

I am insanely scared to touch any more seeds, as I have already wasted ~$150 of seeds now, and none ever really grew up. I wish there was a foolproof guide, but the cocoforcannabis one absolutely didn't work in my case, I tried it 2 times.

Shnoobs58 said:

My PH probe is a brand new Apera PH60, fully calibrated and always washed with RO water, dried, then stored in KCL solution in every use. It's a huge hassle, but I want 100% precision, it's worth it. Also 3-point calibrated weekly, but it's rarely off at all.

EC probe is also brand-new, and fully calibrated. A 1318EC solution gets read at 1315EC, which is 100% fine to me.

Roots look fine, I forgot adding the image when I pulled one of the seedlings out of the cup. I know, not recommended, but I have done this uncountable times in organic soil and it never hurt anything. This is 8 days of root growth, +2 days of germination, so almost 10 days of root growth. This is usually what 4 days of root growth looks like for me, which is rather confusing after hearing so much positive feedback about coco. But it's not the coco, I am doing something wrong here.

View attachment 5399162View attachment 5399163

Water - I don't know. It's fresh RO water, which I usually store no longer than 4-5 days. It has an average EC of 0.04, which is fine for RO I imagine. Then 0.3EC of Canna Calmag, and 0.7EC of Canna A+B, water down to correct EC, fix PH, done.

I am insanely scared to touch any more seeds, as I have already wasted ~$150 of seeds now, and none ever really grew up. I wish there was a foolproof guide, but the cocoforcannabis one absolutely didn't work in my case, I tried it 2 times.

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I can send you free seeds i made if u want to try without any worries… im pretty sure u are overwatering and not letting the pot dry out. Your ec is fine. I grow in coco, i feed my seedlings 1.5ec no issues.

Can you clone? Id try clones to save money ya seeds are expensive unless its a bunch if bag seed or etc, self made.

Those are in coco? They look good in the roots and the leafs in the seedlings in background if theyre in coco.

With mileage varying I tried RO calmg and flora trio it caused massive lock out, was normal when I did tap water .5 ec mostly cal and mag and I think in forms that arent the same as the nutrients being used.

Soon as I removed calmg it worked. But people succeed doing it, adding calmg with nutes not me though. Switching to tap just made things simpler.

Seedlings can be tricky for sure, I much prefer growing from clones. But regardless...

If you've had success starting in Biobizz or some other potting mix, why not keep doing that and transplant into coco when they're ready?