COCO COIR Potassium Deficiency or Nute Burn or what?

[Tumbleweed]

The girls flipped on Friday were fine Sat night, and tonight looked like this. I'm thinking Potassium Deficiency, but there's no yellowing in the margins. So I was worried it might be nute burn, but I've only watered at 600-650 ppm, even with Calimagic added.

It's Potassium deficiency right? Or something else?

EDIT: As I read more on Potassium deficiency, I worry if that's really my problem. I've been watering 2-3 days a week the last week or two, when they are a shade heavier than LIGHT. I've been feeding Fox Farm Trio at half strength every other watering, and Calimagic every watering for the last week or so. The help section says not to worry about nutes because Fox Farm Trio or just about any other cannabis friendly nute line should fix potassium deficiency. But my girls were already on FF Trio. The help section says it's probably PH, but I have always PHed my water/food at 6.1-6.3.

So what do you think?

80°F 55%RH

[Mr.furley]

Fox farm trio at that stage you should be...

5ml grow big
15ml big bloom
5ml tigar bloom
Per gallon every watering, flush once a week

Do you have perlite in that mix?

Side note: it looks like you have Thrips.

[Tumbleweed]

Yes there's perlite. I should have mentioned I'm in Coco Loco, not straight coco.

Do you mean at this stage of deficiency (if that's what it is) or this stage of growth (just flipped)? My last feeding was at 8 ml Big Bloom, 5 ml Grow Big, and 5 ml Tiger Bloom. That's half of the Fox Farm schedule for week 7. You think I should double the Big Bloom? What about the rest of the schedule going forward?

How can you tell about the Thrips? After you mentioned it I looked closer and I see the 'wet spots' on the leaves that I couldn't see until I turned the lights down for the picture. But, I can't find any critters on the undersides of any leaves. I did pick up some Neem oil but don't want to use it until I confirm their presence. I have done two Epsom Salt foliar sprays about 2 weeks and 1 week ago, as I was hadn't been supplementing the coco with cal-mag and think I had a Mg deficiency. When examining the 'wet spots' on the leaves it looked like it could possibly be leftover residue from the spraying???

[ChadWestport]

Do you water to run-off? If so, how much, percentage wise? Do you remove the water from the pan or do you let the roots soak it back in to the pot?

Too much calcium can block uptake of potassium. Be sure you are adding appropriate amounts at the proper times.

If the soil is staying to wet or stays below 60 degrees, they both can cause issue. Could they be contributing?

[Tumbleweed]

I've stopped watering as soon as I see any run-off, and by the time I get the next plant watered the first one will have drained around 15% of the total water into the pan under the pot. I have not removed the water as it has been gone with in a few hours. I didn't think of it until now, but would this process 'rinse' the nutes/salts out of the coco and concentrate them in the drip pan, causing burn when soaked back in? Is removing the water the standard? I can pick up my plants, but how would you remove the water if you were doing a SCROG net?

I've been adding 1 tsp. Calimagic /gal on every watering for the last week. The week before that I added a tablespoon of Rot Stop and a tsp or two (can't remember now) Epsom Salt, as a replacement for cal-mag while I waited for Amazon to take a week to ship the Calimagic.

Two weeks ago, I also bumped my water PH from 6.0/6.1 to 6.3/6.4 as I read Mg likes the higher PH.

Soil temp should be well over 60° (inside tent is 80°, outside of tent is 67°). Been watering every 2-3 days, just before the pot feels light super light as I read you don't want to let coco dry out like you can with soil.

[ChadWestport]

You are correct, you don't want to let coco dry back like you would a soil. Coco needs to remain wet, but not drenched.

Yes, when you get run-off it often times contains condensed minerals / salts and by letting the roots suck that back up, it can lead to nutritional and Ph problems. If your plants are scrogged and you can't move the drip pan to empty it, I've always used a turkey baster to pull the water out. If I were fancy, I'd have a little wet / dry vac to do it.

[CaptainWiese91]

It doesn’t look like a potassium deficiency to me.
But you definitely have a lockout or root problems is my guess.
How much run off do you have when you water ??
But I agree with Chad. Overdue cal mag can block out other nutrients because your soil will get acidic over time.
do you have any kind of root juice ? (Voodoo juice, root juice) or something ?

Potassium overdue would “burn” the lowest leaves in my experience.

[Tumbleweed]

Adding the cal-mag causes the soil to get acidic or the lack of cal-mag causes the soil to get acidic? Do I PH test the run-off to check this? How do I correct it?

I don't have any Voodoo or root juice. But could in another week.

[ChadWestport]

Potassium deficiencies are a weird one though @captainweisel91 the picture he has is what a potassium deficiency looks like. It burns along the leaf margins and then from the tip inward. The depth is much further than a typical nutrient burn and his leaf is burnt pretty far back from the tip. Its odd how so many of the deficiencies and toxicities look similar in this plant.

[CaptainWiese91]

Agreed with how many deficiencies the plant can show. But every time I have giving to much potassium- my lowest leaves have always been burnt. And if I had a deficiency normally the middle leaves would start showing symptom and not the bottom.

[ChadWestport]

You do make a great point Captain

[CaptainWiese91]

I’m not saying I’m 100% right. But it’s my experience of course .

[Mr.furley]

From the pictures The spots look like thrip damage, if you can wipe it off there's nothing to worry about But if it does not wipe off with your fingers look at it closely with a microscope, if it's a patch Where the chlorophyll has been removed then you have Thrips and you need spinosad, sticky traps and ladybugs. Thrips are hard to spot until you have a bad Infestation.

Yes you should be feeding full strength big bloom Especially if your only doing it every other water, your PPMS are on the low side and you should be hitting 1200 ppms. If you are not adding cal/mag that is also a big problem. Coco loco is not soil in anything that came in it by now is spent

Id recommend raising your pots out of the water they are sitting in, flushing with cal/mag water PHED at 6.3 until your runoff matches the input then feed your plants.

Feeding schedule with PPMS

[Tumbleweed]

Will do. Thanks!
What feeding schedule is that? I just realized I was using a soil schedule, not a hydroponic schedule. I was thinking you're suppose to treat coco like hydro, but the schedule you posted doesn't match the schedule I found for hydro either? ( https://foxfarm.com/download/13138/ )

[SoOrbudgal]

Feed them full dose they have missed it.

[Mr.furley]

Listed under Hydro

https://foxfarm.com/feeding-schedules

they change them over the years, the one I circled I downloaded last year


A copy from 3yr ago

[Tumbleweed]

Thanks for everyone's help. I think my problem was both nute deficiencies from running the FF trio at half/incorrect rate (and being late on the cal-mag) as well as PH lockout. While mixing water for the ph/cal-mag rinse Mr. Furley recommended I realized I was not getting accurate readings on my PH meter. After rereading the instructions and making adjustments did the rinse followed by feeding at full strength. Been two feedings since the rinse and the girls, though scared, look healthier than ever before.

Thanks again for the help!