Rust/Brown Splotches. Ca Lockout? P Def?

[Kazman420]

Problem: Rust/Brown Splotches.

Medium/grow method: 70/30 Coco/Perlite. (Canna brick, washed and buffered)

Feed and Supplements: GH Flora Series 6-Part + Hydroguard + Recharge (1x week). 5.8 pH @ 565ppm (.5 Scale). Hand watering 3x day.

Spoiler: Nutrient Chart and NPKs

I'm halfway through Bloom Week 5:

Water source: Tap + Ascorbic Acid (~55ppm, .5 Scale)

Strain/Age: Mephisto: Orange Biscuits - Day 64

Light used: 400w HPS (MH for Veg). 20/4 @ 50 DLI / 700 PPFD

Climate: 50% RH, 73 Room, 70 Leaf. (67 w/Lights Off)

Additional info: I know the GH Flora series runs heavy with N, but this girl has been a champ and didn't show any signs of a nitrogen toxicity. Still, I guess it's possible that Ca and P got locked out?

For what it's worth, there's a HLG 100w RSpec slightly off to the side. (Currently growing 2 plants under it). I've never used an LED before and I've read they can cause extra nutrient use. Parts of this plant are definitely getting LED light from it, albeit not that much. No more than ~30 DLI on one side. I figured it was worth mentioning.

Pictures:

Any help would be much appreciated.

Also, I'm gonna tag in @Mañ'O'Green because he helped me with another plant from the same grow and his advice was spot on.

 

[MIAutomatic]

Long time coco grower here, rust spots do look like calmag deficiency to me.

Are you adding any calmag to your watering? With coco every watering should contain 200-300 ppm calmag depending on if any is added to your base nutrients or your tap water has calmag amounts in that range.

Sometimes tap water will contain a good amount of calmag naturally, but if your water only has a base of 55 ppm then you should be adding 150-250 ppm calmag to every watering.

Also always water to at least 10% runoff to keep the high CEC of coco in check. If you have not been adding enough calmag this whole cycle, or watering with enough runoff, you may need to add a bit extra for a few waterings to get your medium re-buffered and back in balance.

Good luck!

 

[Mañ'O'Green]

Tough call, they are for sure nitrogen heavy. Dark green and shiny leaves. I would do a good flush PH water only and go back in with 150 PPM of cal-mag plus iron mixed in week 6 on this chart.

 

[MrAutoGrower]

Lockout from a salt build up. I am certain of it. Your leaves are deep green and shines, and clawing. Which indicates nitrogen toxicity. It is hard to come out of this when ure in it whilst in flower. Drop your ppms down. Especially if you are feeding daily in coco. Reduce nitrogen levels dramatically and increase P and K. Fertigate many times a day as you can to push as much old nutrients out as possible. The spotting comes out as too much nitrogen builds up. Feed to run off and check run off ppms. I imagine they are wel over 650. Do not feed ur plant just calmag from a flush, or by adding more calmag to your feed. It will make it worse, because right now calcium and magnesium is locked out from the salts and ur plant won’t uptake them. It just adds More salts to the pot

 

[Kazman420]

Hey everybody, thanks for the replies! I appreciate it.

@MIAutomatic I'm pretty OCD about getting 20% runoff everytime, but I've not been adding any additional Calmag to my water. Only what the schedule calls for. (1.9ml/g up until late bloom). I guess I was kinda worried the additional N in the CaliMagic would cause a nitrogen toxicity. Looks like that just about happened anyway, lol.


@Mañ'O'Green In regards to extra iron, what should I be looking for? Chelated iron powder from Amazon? And how much would you suggest adding?


@MrAutoGrower I'll check my runoff EC after this next fertigation and report back. This is only my second grow, so I'm naturally hesitant to mess with ratio's and go off the schedule. Raising P and K would be easy enough since the KoolBloom is 0-10-10, but I'm not sure how I would lower just nitrogen with these nutes?

 

[Mañ'O'Green]

@Kazman420 There are several Cal-Mag + iron products on the market. If you were going to mix your own be very careful as chelated iron can be toxic in very minuscule amounts.

 

[MIAutomatic]

Hey everybody, thanks for the replies! I appreciate it.

@MIAutomatic I'm pretty OCD about getting 20% runoff everytime, but I've not been adding any additional Calmag to my water. Only what the schedule calls for. (1.9ml/g up until late bloom). I guess I was kinda worried the additional N in the CaliMagic would cause a nitrogen toxicity. Looks like that just about happened anyway, lol.

Feeding charts are good guidelines, but that is really all they are. Learning to manage EC and adjust feeding on the fly does take some practice. And that feeding chart does not take the fact that you are using coco into consideration. You can’t treat coco like peat or soil mixes the higher CEC of coco and the high calmag demand totally changes the equation, 1.9 ml of calmag/gal does not even satisfy the coco calmag needs meaning there is no calmag left for the plant. When there is not enough calmag present in coco it will start to bind with K. Now when you add additional calmag it will release the additional K it has stored in favor the easier to bind with calmag. All this also has the effect of locking out nitrogen causing your toxicity issue.

Read up on:

Cannabis Grow Guide - Coco For Cannabis - Science and Practice

Cannabis grow guide: articles, tutorials, DIY projects & more! Dedicated to the science and practice of growing cannabis in coco perlite and other media.

www.cocoforcannabis.com

And check out FloraMax calmag w/iron. In addition to iron it also contains small amounts of all other micros and is a great aid for plants in your situation.

Good luck!




@Mañ'O'Green In regards to extra iron, what should I be looking for? Chelated iron powder from Amazon? And how much would you suggest adding?


@MrAutoGrower I'll check my runoff EC after this next fertigation and report back. This is only my second grow, so I'm naturally hesitant to mess with ratio's and go off the schedule. Raising P and K would be easy enough since the KoolBloom is 0-10-10, but I'm not sure how I would lower just nitrogen with these nutes?

 

[MIAutomatic]

Not sure why it posted my last comment in the middle of a quote? Probably user error on my part. In an easier to read format:

Feeding charts are good guidelines, but that is really all they are. Learning to manage EC and adjust feeding on the fly does take some practice. And that feeding chart does not take the fact that you are using coco into consideration. You can’t treat coco like peat or soil mixes the higher CEC of coco and the high calmag demand totally changes the equation, 1.9 ml of calmag/gal does not even satisfy the coco calmag needs meaning there is no calmag left for the plant. When there is not enough calmag present in coco it will start to bind with K. Now when you add additional calmag it will release the additional K it has stored in favor the easier to bind with calmag. All this also has the effect of locking out nitrogen causing your toxicity issue.

Read up on:

Cannabis Grow Guide - Coco For Cannabis - Science and Practice

Cannabis grow guide: articles, tutorials, DIY projects & more! Dedicated to the science and practice of growing cannabis in coco perlite and other media.

www.cocoforcannabis.com

And check out FloraMax calmag w/iron. In addition to iron it also contains small amounts of all other micros and is a great aid for plants in your situation.

Good luck!

 

[JP1]

Botanicare calmag+ has iron. 2-0-0. 50ppm/ml

 

[Kazman420]

Thanks @MIAutomatic, that's great info! @Jerseyphresh1 Thanks for the CalMag suggestion!


I think there's probably a few issues going on, but based on the replies I'm going to;

1. Flush and get any salts out.
2. Start adding CalMag to my base water.
3. Reduce N and increase P/K by advancing to late bloom nutes.

Will keep an eye on her and report back if things don't improve!