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Need help diagnosing seedlings

Hey all! New to growing, got a question about some seedlings. Larger ones are at day 18 from germination. I'm growing in Canna Coco, using their guidelines. RH around 25%, temp is around 74. Using LED lights.

My problem is the leaves seem yellowed, dry, and curling. Is this due to underwatering? Or could it be from pH and/or EC problems? I give them about half a cupful every night and the soil is still pretty moist just before watering. I've included pictures from the last 3 days. Thanks for the help.
 

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MochaBud

Member of the Month: June 2020
Sounds like your watering too much...let them dry out completely before you water again...and get a ph meter...you need to read @Emilya 's guide to watering a potted plant...good stuff..and usually where noobies make their mistakes ..
BTW :welcome: to the forum and :goodluck:
 

Virgin Ground

Member of the Month: Feb 2020 - Plant of the Month: July 2020 - Nug of the Month: June 2019 - Photo of the Month: Aug 2019
Get your rh up. Vital plant processes shut down with an rh that low. They won't drink, their stomata close and they cannot transpire correctly.

What are you pHing your water/ nute mix to?
 

Growingasmile

Well-Known Member
Hey all! New to growing, got a question about some seedlings. Larger ones are at day 18 from germination. I'm growing in Canna Coco, using their guidelines. RH around 25%, temp is around 74. Using LED lights.

My problem is the leaves seem yellowed, dry, and curling. Is this due to underwatering? Or could it be from pH and/or EC problems? I give them about half a cupful every night and the soil is still pretty moist just before watering. I've included pictures from the last 3 days. Thanks for the help.
Over watering for sure, cannabis likes to dry out before getting watered
 

Rich 3033

Active Member
Your RH is very low like others have said. I'm maintaining a room at 55-60 RH and 22C.

Do you have a ph and ec meter? Without these it's a guessing game and will cause you a headache. Nutrient companies tell you to use the max on the labels.

If your coco is wet then let the pot become light to lift. When it's been cold I've had plants not drink fora week (so you don't have to water every day).

What is your air exchange like? Are they getting fresh air in and the old air out?
 

MickFoster

Well-Known Member
Are you feeding the plants any nutes? You didn't mention it.

I disagree with the above posters regarding letting coco dry out. It's drain to waste hydroponics, not soil, and should be wet all the time like all hydroponic applications. Coco holds 30% oxygen even when saturated, so it's nearly impossible to over water unless it's a small seedling in a very large pot. I suggest adding about 30% perlite when you transplant for even better aeration and fast growth.

These plants are 14 days from sprout and have been fed nutes every day to run off since the day they sprouted.
2 weeks C-99.JPG
 

Rich 3033

Active Member
Are you feeding the plants any nutes? You didn't mention it.

I disagree with the above posters regarding letting coco dry out. It's drain to waste hydroponics, not soil, and should be wet all the time like all hydroponic applications. Coco holds 30% oxygen even when saturated, so it's nearly impossible to over water unless it's a small seedling in a very large pot. I suggest adding about 30% perlite when you transplant for even better aeration and fast growth.

These plants are 14 days from sprout and have been fed nutes every day to run off since the day they sprouted.
2 weeks C-99.JPG
You may disagree with me mate but look at her.... she's getting a drink every 3 days. I never let it dry out, she gets a drink before any leaves show signs of dehydration.

So you know that's 1.5m2, one plant.
 

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Wow guys I'm blown away by the quick responses, expertise, and community vibe here. I'm brand new to this forum so it's very encouraging to see all the support.

Since I got so many responses, I'm gonna narrow down my answers to the few main points you all have made.

1. pHing - I haven't been pHing my solution yet. Yeah I know, amateur move. But the decent pH meters are expensive and I had to wait for my next paycheck to get one. Anyway, it's currently in the mail and should be in tomorrow. This goes for the EC meter as well. I know this could all be a pH problem, just wanted to see if anyone here thought so as well.

2. Overwatering/underwatering - this is where there's a lot of disagreement with you guys. I started off by underwatering my seedlings and it definitely showed. Burning, yellowing, stunted growth at first. I upped the watering and it brought them around quite a bit. Also the leaves don't show the characteristic drooping of being overwatered, and appear crinkled and a little yellow, which is more symptomatic of underwatering (from what I read). Since I'm no expert, though, I appreciate getting input from both sides of the argument.

3. RH/ventilation - another amateur mistake. I put an 8-inch hyperfan in my 4'x4'x6.5' growbox. Even though I know it's way bigger than I needed, I wanted a hepa filter as my intake and those things are hard to get air through without an additional fan for intake. This fan works great at exchanging air...a little too great. My RH values were consistently around 10% despite repeated measures at getting moisture in my box, and the fan being turned down to minimum speed. I finally ended up splurging on a Can-filter for a bit more resistance and my RH shot up to 25-30%. I'm surprised that this would have so much of an effect on my plants though, because most growers say 40-50% is the sweet spot and 30% doesn't seem like a far cry from that. I will, however, continue to try and get my RH up.

4. Nutrients - being a new grower, I went all out on the Canna products. I got all their nutrients they recommend and mixed them up as per their instructions. If this is a nutrient problem, it's likely happening at the roots (ie. pH or EC issues) and not due to underfeeding.

Ok so thanks guys, what an awesome group to bounce ideas off! Your plants look great, despite the disagreements in watering regimens lol. Any ideas on how to get RH values up that don't include buying a humidifier?
 

MickFoster

Well-Known Member
Wow guys I'm blown away by the quick responses, expertise, and community vibe here. I'm brand new to this forum so it's very encouraging to see all the support.

Since I got so many responses, I'm gonna narrow down my answers to the few main points you all have made.

1. pHing - I haven't been pHing my solution yet. Yeah I know, amateur move. But the decent pH meters are expensive and I had to wait for my next paycheck to get one. Anyway, it's currently in the mail and should be in tomorrow. This goes for the EC meter as well. I know this could all be a pH problem, just wanted to see if anyone here thought so as well.

2. Overwatering/underwatering - this is where there's a lot of disagreement with you guys. I started off by underwatering my seedlings and it definitely showed. Burning, yellowing, stunted growth at first. I upped the watering and it brought them around quite a bit. Also the leaves don't show the characteristic drooping of being overwatered, and appear crinkled and a little yellow, which is more symptomatic of underwatering (from what I read). Since I'm no expert, though, I appreciate getting input from both sides of the argument.

3. RH/ventilation - another amateur mistake. I put an 8-inch hyperfan in my 4'x4'x6.5' growbox. Even though I know it's way bigger than I needed, I wanted a hepa filter as my intake and those things are hard to get air through without an additional fan for intake. This fan works great at exchanging air...a little too great. My RH values were consistently around 10% despite repeated measures at getting moisture in my box, and the fan being turned down to minimum speed. I finally ended up splurging on a Can-filter for a bit more resistance and my RH shot up to 25-30%. I'm surprised that this would have so much of an effect on my plants though, because most growers say 40-50% is the sweet spot and 30% doesn't seem like a far cry from that. I will, however, continue to try and get my RH up.

4. Nutrients - being a new grower, I went all out on the Canna products. I got all their nutrients they recommend and mixed them up as per their instructions. If this is a nutrient problem, it's likely happening at the roots (ie. pH or EC issues) and not due to underfeeding.

Ok so thanks guys, what an awesome group to bounce ideas off! Your plants look great, despite the disagreements in watering regimens lol. Any ideas on how to get RH values up that don't include buying a humidifier?
Checking and adjusting the pH of your nute solution is a necessity. I don't own a pH meter because they require calibration, calibration solutions, and I don't trust them unless calibrated regularly. I have been using the pH drops for several decades - it's cheap and it's never wrong. I also don't own a ppm meter because they're not necessary unless you're growing in DWC.

There are different schools of thought when growing in coco. Here is mine. As I mentioned in an earlier post - coco is drain to waste hydroponics, not soil, and it shouldn't be treated as such. I use a 70/30 coco/perlite mix which makes it airy and allows for more oxygen to the roots, which in turn produces very fast growth. Daily feeding to substantial run off refreshes the nutes, pulls in fresh oxygen to the roots, and prevents salt build up. You should always feed to run off and never use plain water because it can mess up the cation exchange capacity. I feed daily to run off from sprout with 1/4 strength nutes and increase as the plant grows. When I switch to flower I increase my feeding to twice a day - some people feed multiple times a day. Overwatering is difficult with coco because as mentioned it holds 30% oxygen when saturated. The only time overwatering can be a problem is when a very small plant with a very small root system is in a large pot.

My only suggestion for raising the rh is to run a humidifier.

I have never used Canna products so I can't comment, but other growers use it with good results. Good luck. :)
 

drummer69

Active Member
Hey boyz!
Yeah I'm new as well but the guy that used to be a master grower near me has me hooked on nothing but Coco, I do not add perlite to mine just straight coco media and I have not ever had a over-watered lady yet. I love the stuff and will never use soil ever again . Even thinking of making some raised beds for herbs and some veggies with the stuff this spring
 

dakotamoon

Well-Known Member
Many of us coco growers have had to install RH controllers - now that the winter low humidity is here. I bought an Inkbird for $50 CDN, and have a large humdifier in the tent. You might want to get a temperature controller as well - or find some way to only have your 8" fan come on momentarily. When my 6" fan comes on it sucks all the RH controlled air out of my tent, this is only a problem in the winter time. Some things to consider, RH is very important.
 
Hey everyone, just wanted to catch up with yall since everyone was so professional and contributed so much expertise. First off, I created a new batch of nutes and pH'd it to 5.8 and brought my EC to 1.6. I transplanted my oldest plants to bigger, 5 gal smart pots. Next, I began watering them less, about every 2-3 days instead of everyday. Finally, I put in 4 large round plates filled with water as a makeshift humidifier. This has brought my RH to around 35-45%. Daytime temperature is around 68-72 deg. Nighttime temperature is around 55-65 deg.

I posted a pic so you can see the change. Thanks for all the great advice folks!
 

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TheNuttyProfessor

Well-Known Member
i would feed daily also ( but every one has their own wee tips and tricks ), keep it wet but near the end i start given drought conditions as it can help make the plant more potent , let is droop slightly, then water slightly again , keep doing this until she uses most nutes and is flushed , then hanging up in a dark room upside down the plant will still think its living as it can still get nutes running down to the stems , even the sugar leaves will become more potent and close in around the buds :)
Good come back though , your back on track :D
 

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dakotamoon

Well-Known Member
@splice, you may think you are doing your plants a service by only watering every couple of days, but legions of coco growers have found: "at least daily feedings, sometimes 3x a day in bloom" has been how most coco growers have produced amazing crops! For example .. in my first coco grow .. I water my plants at least once a day, and once they hit the bloom stage, I will increase to 2x daily. For a comparison .. in my last grow ..[soil grow - first grow] .. I only managed 1.6 ounces of pot. With this my first coco grow .. with daily watering - I have so far harvested over 3 pounds of trim .. getting my ladies ready for the bloom stage.

All I'm saying is: hundreds of other growers have had great results with daily (or 2 or 3x daily) in a Coco grow.
 
@splice, you may think you are doing your plants a service by only watering every couple of days, but legions of coco growers have found: "at least daily feedings, sometimes 3x a day in bloom" has been how most coco growers have produced amazing crops! For example .. in my first coco grow .. I water my plants at least once a day, and once they hit the bloom stage, I will increase to 2x daily. For a comparison .. in my last grow ..[soil grow - first grow] .. I only managed 1.6 ounces of pot. With this my first coco grow .. with daily watering - I have so far harvested over 3 pounds of trim .. getting my ladies ready for the bloom stage.

All I'm saying is: hundreds of other growers have had great results with daily (or 2 or 3x daily) in a Coco grow.

How come they seemed overwatered? I've had so many people say they seem overwatered, not just on this forum but others as well.
 
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