HELP! COCO COIR - Yellow leaves, young plant

[karryn]

Hi all,
I have what seems to be a regular issue here, but any help clarifying what's my actual problem is and (more importantly) how to fix it would offer great peace of mind!

I'm growing a young plant in Coco Coir and the tips of its leaves started bending down and got a yellow color.
I noticed it yesterday on the lower set of leaves. Today the upper set grew a bit more and developed the same symptom - yellow tips, bent down.

I'm using:

• lights: SF-1000.
  • Yesterday: I had them at 30cm from the plant, at around 80% intensity.
  • Today: I moved them further away, at 40cm, and dropped down the intensity to 60%, fearing I was burning them. But, as I said, today the upper set of leaves got yellow just as well...
  • Following a schedule of 18h of light, 6 of darkness
• Watering:
  • Every 2 days, once with nutrients (Micro 1/2, Gro 1/2, Bloom 1/8), once without. Always with CalMag - 1 tsp per gallon
  • Using tap water, treated for pH after all the other stuff is mixed in
  • Usually I settled for anything between 5.5 and 6.5 pH, most of the times somewhere under 6
  • I watered them again this morning (last watering was on Monday) and today they had just water + CalMag, with a pH of 6.2
    • best pH ratio I ever achieved
• Temp / humidity: I started keeping a log, noting down values every hr or so
  • 23-24 C during the day, with a humidity between 45 and 57
  • 21 C during its 6 hrs of "night time", humidity around 57 and 62. Mostly around 60-61.

Could be nutrients, could be the light was too close, could be the CalMag or not enough watering? Before today I didn't really know how to tell if the soil was dry or wet, it always looks about the same for somebody with no prior experience. Today I wet a part of it, ran my fingers through the wet part and then through the dry part to compare the two and it feels like I haven't been watering them that well ... it may be they were a bit in need of a drink. Can't be sure though, I did follow the "Water them every 2 days" advice....

Please help.
Any help's appreciated. I want to learn how to take good care of them, and that means me understanding their language. I'm trying my best but so far I don't know in which direction to take steps, if any. Maybe it's better to wait it out and not do anything for now, for fear of making it worse?

Thanks,
k

[AGH]

Hello Karryn and welcome to growing and the forums!

From your post, I can tell you're very detailed oriented and you want the best for your plants and that's good! Rest assured that you're experiencing something that pretty much every one of us have fallen victim to: loving your plants too much.

Your little plants are babies right now and they actually need very little input from the grower at this point beyond keeping the environment in check (temp, humidity, watering regime) and it seems like you're doing a pretty good job with the temp and humidity and the watering sounds about right too, although you don't mention how much you're watering each time you water.

Using the info you gave and the photos you posted (great job doing that!), it looks like you have some nute burn. When plants are that small, they really don't need many nutrients so you can definitely cut back on those for now.

Additionally, you might consider your watering regime, which it sounds like you're aware of. Watering a small plant in a big pot is a bit of a balancing act. You want to make sure that the plant has moisture, but since it's so tiny, it only draws up a small amount. At this stage, you really just want a little water around the base of the plant our to a few inches - roughly to where the edges of the leaves are. You mentioned that you're growing on coco coir but you also mentioned soil and the photos look like soil so maybe it's soil with coco coir mixed in? A rule of thumb for watering soil: take a handful of soil and give it a good squeeze. When you open your fist, the soils should stay together and if you gently touch it with your finger it should fall apart. That means it's at the ideal moisture. If it doesn't stay together it's too dry. If water squeezed out like you're squeezing a sponge or if the ball of soil stays together when you poke it with a finger, it's too wet. Combine that with getting a feel for how heavy the pot feels when it's moist vs dry along with close attention to how your plants respond to watering and the frequency and amount of water you're providing and you'll get the hang of it!

Overall, I think if you pull back on the nutrients for the time being and make sure your watering regime is dialed in, I think you'll be good. Keep up the good work managing the environment (making sure to adjust it as the plants grow and enter different phases) and you'll be set up for a strong finish!

Keep us posted!

[karryn]

Hey AGH, thanks for the reply and the kind words!

After reading your post I tend to agree its the nutrients. I'll dial down on them.

Let me offer some more details on what I previously missed:
Currently I'm using around half a gallon per watering. I fill a bucket with the usuall 1 gallon of water, mix in the nutrients (using this table as a reference https://www.growweedeasy.com/wp-cont...s-schedule.pdf amazing job for the creator!), then pour it in a bottle and use around half of what's in the bucket. I pour gently from the bottle around the baby plant, in a circle with the radius of a few inches. I have a fabric container so there's some runoff in a plastic tray underneath, I throw away the runoff and that's it. 2 days later, I come back to water it again.

The medium: It's Coco coir. I did mention soil but what I really meant was "the stuff that's under the plant". It's part coco, part perlite, and I mixed half a liter of worm castings fertilizer in there as well in the beginning, to give it a good start. (5 gallons container but I'm using it as a 3 gallons one for now, with the upper part tucked in like a sleeve).

Thanks for the tips, that's a very nice way of testing the medium to tell how wet/dry it is!

I guess I should keep giving it calcium and magnesium with every watering? And maybe skip on the others for a couple of waterings.
If everything goes well from now on the new leaves should be okay, but the old ones will remain like this? (then again, if they keep growing, those small affected areas should go away in time or become even smaller to the point they're no longer an issue)

In closing, I was really happy to read your reply, it eases my mind to know ... y'know, that it'll be alright.

[Bluey]

You could probably go to 60cm and 50% on that light and keep the nutes as recommended by the manufacturer, or a bit less.
I also grow in coco. I don't know about adding worm castings to it...I just keep it 100% coco and all nutes in the water.
There are a couple of pretty reasonable light meter apps you can install on your phone to give you a rough idea of what distance and dimming to use....try not to push your plants too much..I prefer a conservative approach as there are less problems with nute deficiency under the strong LEDs

[karryn]

Thanks Bluey!
I'll start by raising the lights to 60cm, dim them off to 50 and take it from there. Keep the nutes.

I had no idea we even have light meter apps, heh, that's actually pretty awesome. Any recommendation or just pick one of the most downloaded and go with it?
Curious what it'll say.

[Bluey]

I've used 2 different ones on 2 different phones. PPFD Meter & Photone.
They are both about as good as you can get using your phone which is not great. Best if you find some reviews on your exact light and see at what height it produces X amount of light and go from there...at early veg 200 ųmol/m²/sec is ok..500 to 1000 in flower but always monitor and less is more

[PRIMO]

karryn If you have an extra fiber pot, put 3 gal. of coco in it and keep it close to your grow. Instant weight reference.

[bboyfromwayback]

It’s nearly impossible to diagnose an issue through pictures. Especially when a lot of problems look the same. First glance at the droopy leaves and I’d say you’re overwatering. When you’re hand watering it’s best to pick the pots up and don’t water until they’re extremely light. Second, make sure you’re giving it plenty of nutes, especially cal mag. You have to supply all the nutrients in coco, if you didn’t pre water the medium well prior to planting then that could be another issue. The plants very young, it’ll recover quickly if taken proper care

[karryn]

Thanks all, I appreciate it!

@Bluey: cheers, going with the lights manufacturer's recommendations for now (which are the same as yours). Will install one of the two apps just to monitor and keep an eye on them.

@PRIMO: hah, that's a great trick! Thanks for sharing. Simple and elegant, though I wouldn't have thought of this on my own anytime soon.

@bboy: I haven't done anything to the medium before planting, except for mixing the worm castings.
I think I'm ok with calcium & magnesium dosage unless a lower pH (between 5.5 and 6) meant they didn't absorb them well enough. The other nutrients, I might have overdosed.
Overwatering could also be an issue, as I wasn't able to tell if they needed it or not.

Quite a few things to be mindful of for the next couple of days. Must say, I'm starting to get into the growing process.
Dreaming of the harvest, of course, but just growing them well has its own beauty.
So far, the new set of leaves seems okay, haven't spotted any issues with them yet.
For the record I haven't watered them again since Wednesday. Only thing I've done was to raise the lights and dim them down.

[Mollisol]

Hi Karryn. Lots of great advice above. I have found overwatering is extremely easy to do. I picked up a graduated pitcher. So I could record the exact amount of water given to each plant. Having a base line in my journal has helped me.

[karryn]

Hey Mollisol, how's it going?
Yup, agreed about the advice above!
One question about your pitcher: when your plants were about the size mine is now, how much water were you giving them?
A graded pitcher is another very nice idea I'll put in practice.

An update about mine: a new set of 2 leaves grew since Wednesday. They both look healthy. So far it's going in the right direction!

[Mollisol]

Hi! Doing good. I can't give you an accurate answer on water. I have a different set up. My plants were in 16oz cups at that stage. I went from cups -> 2 gallon pot -> 5 gallon pot. The big pot is where I ran into all kinds of problems. So started measuring. The smaller pots I could eyeball and get pretty close. With a few mistakes.

[Mollisol]

Sorry that was not more helpful