Jacks in Coco issues

Hello everyone,

This is my 2nd grow, and first time in coco. I’m in about week 5 of veg and I have not had the best run of things to be honest.

I’m in 5 gallon pots in coco
RO water
Jacks 321 with silica
240 watt LED light in 3x3 tent
Humidity around 65-70 Temps 65-70
I water maybe once a day with a PH of 5.8.
The run off PPM were as high as 1600 but are now down to around 400
Strain is Strawberry cough.

It doesn’t seems to been getting better and at this point I am not sure what I can do. I looks like nitrogen toxicity (although not dark green) but also like its been overwatered (I have been flushing it) which I though it was hard to do in coco.

I wish I had more to contribute to this community other than asking questions but any help would be appreciated.

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I would suggest temps need to come up ten degrees or so. 65 to 70 is a bit low.

How many plants under your 240 watts of light and how big is your tent?

FYI flushing using Jack’s is unnecessary. I would keep your input TDS at or around 900 ppm during veg. That will bump up to 1,100 or so in flower.


Im not a expert on coco. But in all that i have read, if your tds is higher then it should be when fertigating daily…a-your not watering with enough runoff, b- soil is drying too much causing tds to rise. Cocoforcannabis is a great resource to read if you have not already. Im interested to hear the other responses. But as stated above, raising temps will help but do believe it is not the cause of that look.


Just two plants and I have the light at about 70 percent at about 20 inches. How do I control the tds? By adding more pure water after the Jacks is mixed?

Thank you I’m going to check that out now.

@Graysin ?

What are the PPMs when you feed, and how do you measure your Jacks? (Teaspoons, grams, and how much of each?)

What brand of Coco is this?

Thanks for the tag, @JaneQP :v:


Adding more plain water will dilute your nutrient solution and lower the TDS. Adding more nutes in increases the TDS. Ideally your runoff ppm will be about 150 ppm (300 EC) higher than the ppm of your nutes going in. As @Poseidon1 said check out cocoforcannabis. Start with the article called “Understanding EC, PPM & TDS for Growing Cannabis”. After that read about ppm/EC targets and then how to manage cannabis fertigation by runoff EC.



Was also thinking this when reading original post.

Great question!

This too low. As mentioned earlier you should be flushing out most with each feeding and probably just need to feed to more runoff, or slower, or maybe both. If you flush coco significantly you pretty much need to follow up with reset of nutrients.


Crank that light up to 100% which will help to bring temps up and increase plants’ uptake of nutrients and growth. This alone may solve your leaf issue.

Likely you will need to almost double your lighting to get good flower yields.


The thing I noticed is the “I water maybe once a day…”

I my grow was in coco-perlite & I was fertigating 2 to 3 times daily to runoff.

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Good point: coco needs daily watering.


The brand of coco is CANNA and I measured the 3.6 of part A 2.4 of part b and 1.1 of Epson by the gram.

I have a second 240 watt led that I don’t have up yet. I over did it with to much light my last grow so I was waiting to introduce it until right before I flip. I use a watt meter to gauge how much they both are putting out.

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I mainly backed off due to harshness of of the clawing. Should I be giving full strength multiple times a day?

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Can you not over water coco?

Every feeding of jacks should be full strength with 10-15% run off :v:

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I probably would have too, but this can also be caused by too much air blowing over plants or insufficient watering/feeding habits.

Feeding multiple times a day is reality for many of us but not necessarily required for everyone. There are a lot of variables to determine whether an individual should or shouldn’t. Assuming you feed to good amount of runoff at or around lights on, how long until pots are dry?

Coco is like a hybrid of hydroponic & soil. I imagine you can overwater but you’d have to try hard to do. It has a low pore water pressure (how much water pressure can be held in the voids of the soil).

I try not to let them get completely dry like soil would. I thought I was giving them to much water so I backed off a bit as well.

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