First time coco, high light and envi. control

Hello all, looking for guidance dialing in my setup as I start my journey with coco. Previously a soil/organics guy, but am keen to see what I can achieve with my new rooms.

4x4 Flower setup:
2x GLA 480w fixtures
13k btu mini split
3gal air pots
Canna coco (unbufffered )

2x4x6 veg setup:
400w max Vero 10 diy build over shelving

The flower room will be sealed up once I've gone through a cycle or two, selected my phenos, and built my controller. The flower room is currently being used for veg/pheno hunting. I've got 1x Durban thai, 1x 24k Gold, 2x Blue cheese, and 1x Bride Cake auto flower. They are all in their 4th week.

My starting water has no detectable EC. I'm using CX coco A&B plus regenaroot @1ml/L for an EC of 0.8 @ 6.2pH.

I've started to see deficiencies crop up in the last week and I'm not sure how to tackle them (photos attached). While the plants looked overall healthy and lime green, rust colored spots started to appear on the lower leaves. They have started moving up the plant. Over the last couple days shoots on the auto flower have started to uniformly yellow, while the main apical on the other plants are developing a yellow/bronze hue. Seems the faster growing plants are suffering the worst.

I'm assuming this is a cal/mag/iron issue. However I'm not sure whether it is underfeeding, a cation exchange issue, or a pH issue. I'd like some advise on what I should prioritise first and how long I should wait for a response, as I'd rather not dig a deeper hole.

Cheers!

Looks like calcium def on lower leaf......and coco is unbuffered ? If so it's likely robbing you of the calcium to satisfy the cations among other things .

I ran into similar problems first time running coco ,believing the PRECHARGED claim ...... Cal mag will be your friend for a while I'm guessing .But there are some coco gurus that I'm sure will chime in and let you know what's up FO SHO lol

Green Puddin said:

I ran into similar problems first time running coco ,believing the PRECHARGED claim ...... Cal mag will be your friend for a while I'm guessing .But there are some coco gurus that I'm sure will chime in and let you know what's up FO SHO lol

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Chur. The coco is Canna pro, it comes buffered but I didn't 'break' the buffer by precharging. CX nutrients has what appears to be a reasonable amount of cal in it (see attached), and they do not sell a specific cal/mag, so I'm not sure how best to supplement it.

It could also be that I'm giving them too much light. Up until 48hrs ago I was running my 400w Vero array about 1.5ft above them, I noticed the spotting early in the week so bumped up the feed by 0.25ml/L. Next day the spotting was worse, so dropped feed back down.

48hrs ago i switched to my new light (gla 480w) at about 1.5ft height, and fed at 1ml/L as there was no burning on the tips from the initial feed increase. 24hrs ago noticed the yellowing/bronzing so have raised the light to 3ft until I set up a dimmer. Today the yellowing hasn't got worse but the spots have and the growing tips are still bronzing.

Wondering if the initial light may have been to strong and I've been chasing a nutrient issue instead.

@Prawn Connery , would you chime in as im using your nutes and lights your familiar with

I started Coco and did stupid shit.

I had one plant that had similar discolored meristem growth. But the stem was not red like it appears in your first pic. My plants were turning yellow and had the burned spots.

I assumed CocoTek supplied enough so I had never fed just CaliMagic.... : |

I foliar fed CaliMagic a couple times and fertigated CaliMagic at about what I was feeding them prior with [email protected]. I don't think I used it often enough, it took 2 weeks to get better.

I'm now strictly doing feed-Calimagic-feed-Calimagic because I ran into issues again. I probably don't have the best advice, haha

athlete said:

I started Coco and did stupid shit.

I had one plant that had similar discolored meristem growth. But the stem was not red like it appears in your first pic. My plants were turning yellow and had the burned spots.

I assumed CocoTek supplied enough so I had never fed just CaliMagic.... : |

I foliar fed CaliMagic a couple times and fertigated CaliMagic at about what I was feeding them prior with [email protected]. I don't think I used it often enough, it took 2 weeks to get better.

I'm now strictly doing feed-Calimagic-feed-Calimagic because I ran into issues again. I probably don't have the best advice, haha

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Is 6.5 not a bit high for coco?

Sounds like you are on top of it.
Unfortunately, I'm not familiar with the nutes you are using.

But I suspect you need more Ca and Mg. And agree the lighting was a bit much.

Using Jacks 321 nutes I run a ec of around 1.2 minimum.
Ph 5.8 thru 6.2


My hobby Coco grow

The Cal/Mag issues I just had I solved by using 1 tsp Epsom in a 1 liter spray bottle and leaf treated the plant a number of times daily, Think I have it under control.

TintEastwood said:

Sounds like you are on top of it.
Unfortunately, I'm not familiar with the nutes you are using.

But I suspect you need more Ca and Mg. And agree the lighting was a bit much.

Using Jacks 321 nutes I run a ec of around 1.2 minimum.
Ph 5.8 thru 6.2

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Cheers, I checked this morning and seems the upped feed and reduced light has had an effect.

@Prawn Connery is running the same nutes at 3x the strength under a similar powered light.

I'll probably up the feed strength by 25% again tonight and just let the plants grow toward again.

Seems the auto flower is moving into stretch mode too, so that will bring a new learning experience!

Bit of an update. Was definitely a combined case of underfeeding and over lighting.

I upped the feed by 50% and raised my light as high as it could go. Ended up giving them a bit of nute burn, but the beauty of coco was that I saw this the next day and was able to drop back on the feed accordingly.

Everything is looking happy and healthy and smoothly moving in to flower!

You should not be able to see much in 24hrs from feeding. I 100% agree , way too much light at first. Keep that light high until you need it. when she starts showing "burns" then you need more light.

Never heard of the food you are using but it looks like a VERY balanced diet for veg! great stuff you have there. You may or may not need extra calmag with that food. i might have to grab some of that.

Going by that chart, you are getting plenty of both Ca and Mg. Im not sure how they break down their two parts but it seems all together its got 6-1-4 with 4% Ca and 1% Mg plus tons of other goodies...... im getting sucked into the marketing hype on their page. I have never seen a liquid food contain everything like that does. Its really hard to mix all that stuff into a shelf stable liquid so it seems they have done some extra homework.

getogrow said:

Going by that chart, you are getting plenty of both Ca and Mg. Im not sure how they break down their two parts but it seems all together its got 6-1-4 with 4% Ca and 1% Mg plus tons of other goodies...... im getting sucked into the marketing hype on their page. I have never seen a liquid food contain everything like that does. Its really hard to mix all that stuff into a shelf stable liquid so it seems they have done some extra homework.

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I ended up going and grabbing their full range, about $250 local all up, not cheap but it'll go a long way. The additives have meant i can/have back/ed off the base nutes a bit (eg. Using the high N grow booster). Also having all the nutrients split out in that way means ill be able to create a spreadsheet and delve deeper into nutrition when I get to the point of wanting to do so. I'll also be able to diagnose problems easier when they arise as ill be following the complete feed schedule.

I'll be surprised if I need extra cal/mag as the product is made for coco and they don't have a specific calmag product. Watching @Prawn Connery use this line he didn't require any and at least im now able to recognize the earliest signs of deficiencies (leaf edges curling upward).

I was definitely able to see the results of too strong of a nutrient solution within 24hrs. Im fertigating every second day with high runoff. It would start as darker splotches on the middle leaves the next day, which would then progress to typical rusty necrosis and burnt tips over 72hrs. Catching this the next day and fertigating with half strength of the last feed would reduce the extensiveness of the burn, but the severity would still progress as the tissue damage had been done.

I'm finding that a three foot plant in a 3gal smartpot will generally take up to 1.25ml/L of the base formula before showing signs of burn. I started seedlings with 0.25, and have increased feed by 0.25ml each week after the first two weeks. In the 6th week of veg I've been feeding at 1ml a&b and 1ml of each of the additives for an ec of 1.8. I've decided this is providing a bit too much N as the plants are a bit darker than id like (but loving it), so will reduce the a&b back down to 0.75ml/L. I've just topped them back to the 3rd internode so will be halving base nutes for today's feed and flipping the lights next week. pH unadjusted comes out at 6.2 and I'm not noticing any issues with that.

lazaah said:

I'm finding that a three foot plant in a 3gal smartpot will generally take up to 1.25ml/L of the base formula before showing signs of burn.

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Your on the right track but be careful with your "tests". "Burns" and defs dont show up that quick....its almost impossible.
If your 3 ft plant was to run out of Ca today , then you would not have any idea until it shows you. (days at least) "burns" show quicker. A nute "burn" is actually too much of one thing/s locking out others. There are very few elements that a plant can take up too much of. Almost every "burn" you see is actually a def.
Too much food will throw your medium all out of wack and cause the ph to fuck up a long with the microbiology of the soil/coco/soiless, thus it will show defs because it cant get to an element it needs.

Hi mate, I'm sorry I'm late but I haven't checked in to RIU for a while.

So the first photos were general underfeeding, as you guessed. The rust spots are calcium whilst the rest of the growth is showing a slight magnesium deficiency (yellowing, slight interveinal chlorosis), zinc (new growth leaf twisting), and possibly boron (slightly red-brown hue from the new growth).

The very tops of the plants have a striped yellowing effect which is light stress. You can tell, because the lower leave don't display this. So you were experiencing a combination of not enough nutrient and too much light – which is common under LED for new users. LEDs tend to be stronger than growers give it credit for and it also contains more blue light, which can more easily lead to leaf temp rises and bleaching. It's more common to see this under so-called "veg" lights than flowering lights that have less blue in them.

I used CX nutrients for years and I can tell you that 1ml per litre is not nearly enough. But you are also using the new CX line, and I used the old line (see below).

CX nutrients are designed to mix with typical tap water which usually has some calcium-carbonate and magnesium-carbonate in it (usually from limestone groundwater sources). Likewise tap water usually has some zinc, copper and iron in it from the metal pipes and plumbing. If your water is soft (low EC) then it will be missing a small but significant source of Cal-Mag and you may need to add more – even though CX coco nutes have quite a bit of calicium and magnesium in them already. The problem may be worse in the beginning with fresh coco that's not charged, or it could get worse during the grow as the coco breaks down and its surface area increases, which causes more cation exchange and greater demand for calcium and magnesium.

Nitrogen also helps with magnesium uptake, so low N levels – especially if you are underfeeding – will exacerbate the problem. Higher pH will help cal-mag uptake but will affect heavy metal uptake (iron, zinc, boron, copper etc). pH5.6-5.7 in veg is a good number to aim for, and around 5.8-5.9 in flower.

I used the old CX formula which had dedicated NPK ratios for veg and bloom – the new formula uses a "base" two-part nutrient that must be supplemented during veg and flower. So the base nutrient will not have enough nitrogen for veg and it won't have enough PK for flower – that's why you have to add the Growth enhancer (NPK 11-0-0) during veg and the head master (1-2-2) during flower and mighty bloom PK (0-15-16) during mid-late flower. Those nutrients are designed to be used in conjunction, not separately.

Finally, you need to be careful reading those CX nutrient charts because they can be quite misleading. For example, have a look at the NPK ratios of the Coco A and B below. The ratio is 4-4-5. But have a look at the nutrient chart – the NPK ratio is 6-1-4. So which one is correct? And does the nutrient chart incude all the additives and if so which ones?

Just be careful about which nutrients you think you are giving your plants and what ratios they are, as you may not be giving yourt plants what you think you are. Excessive K, for examnple, will lock out both calcium and magnesium, so if you were just feeding the base nutrient without the Growth Enhancer, that could be your problem there.

Prawn Connery said:

Finally, you need to be careful reading those CX nutrient charts because they can be quite misleading. For example, have a look at the NPK ratios of the Coco A and B below. The ratio is 4-4-5. But have a look at the nutrient chart – the NPK ratio is 6-1-4. So which one is correct? And does the nutrient chart incude all the additives and if so which ones?

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This is why i didnt buy some..... i dont like misleading labels. This one is confusing but i bet the food is good...it seems well rounded.

getogrow said:

This is why i didnt buy some..... i dont like misleading labels. This one is confusing but i bet the food is good...it seems well rounded.

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Cheers @Prawn Connery and @getogrow, my autoflower is looking happy going into its third week of flower and I'm picking up on how to keep the others in perpetual veg (I seem to be cycling through too hungry, perfect, then overfed).

For now I'm going to follow the feed schedule ratios, even if I'm not using full strength. Im a couple of weeks off flipping the photos for the pheno hunting, so Im probably a few weeks of really drilling down into calculating and tracking nutrition. At which point ill fire an email to the company asking for clarification on the charts, utilize the spreadsheet from @Renfro, and start properly tracking things.

The chart they provided is definitely in excess. For example, if I use 1ml of A+B and the additives, I end up with an EC of 1.8. The plants show issues (dark splotching) at the start of the next light cycle.

Cheers again, ill probably keep maintaining this thread as a bit of a journal. Im looking forward to the day I get to throw both of my lights at full power at a full canopy!

Guess I've got another question, which is, are pH swings important when hand watering? At this point my pH naturally settles to 6.1 after adding nutes so I haven't bothered adjusting it. Wondering if it would be beneficial to go low-medium-high throughout the week? I understand this will likely happen naturally when I switch over to the auto system