Rust spots on one plant

I have been having rust spots on mainly just one plant. It is in oceans farm soil. Feeding jacks 321 with 20% runoff every 2 days with watering. I did have light stress a week ago or so before I re adjusted my lights I don’t know if that matters. The PH in is 6.4 and PH out is 5.3 ( always about 1.0 less than what goes in). PPM out is 850. I gave it a dose of cal mag a few days ago in case that was the issue. Any help here?

One other plant did have 1 or 2 leaves with minor spots like this but this plant has it worse. The other plant seemed to correct itself.

In my opinion it could be a calcium or magnesium deficiency…happy gardening

:point_up_2: most likely the culprit. Soil PH range is 6.2-6.8 with the sweet spot of 6.5. I’ve seen some between 6.0-7.0 but doesn’t thrive on the low or high end. With the PH that low the plant roots are not absorbing nutrients. It very well could be a calcium deficiency coupled with several other nutrients. With it that low I would flush the medium with 7.0 water and check the run off PH and PPMs. It’s going to take 3 times your grow pot size in water to get that back in range :love_you_gesture:


Thanks I will do and I had thought ocean farms was supposed to PH balance if I put correct PH in? Also I just watered this morning should I wait a day when I would normally re water ( I do every 2; day’s as of now) or go ahead and flush now?

1 Like

Soil likes a wet to dry cycle, depending on your pot size and medium make up of soil to perlite ratio the frequency could be 2 days to 4. Always feed or water to run off of at least 20% of what you’re pouring in the top to come out the bottom. Not doing this can create a lock out as well with the salts from the nutrients accumulating in the root zone. Think of the run off as a root rinse. Using a little dolomite lime tilled in an inch or so below the surface will help raise and stabilize the PH :love_you_gesture:

Yea I use a gallon and that gives me almost exactly 20% runoff everytime. I’ll flush it when I re water again since it’s only about a day from now. After I flush since it’s already wet should I go ahead and add my nutes? (Jacks 321)

1 Like

Do you have a TDS pen to check PPMs? FFOF is good for roughly 6 weeks with water only and testing the run off PPMS let’s you know when to feed for the 1st time and how much to feed there after. Soil mediums should go feed, water feed in that sequence and depending on the run off PPMs it could be back to back water only. When I use the FF mediums I start feeding nutrients (Jacks) when it drops below 800 and I maintain 1000 PPMs through veg and 1000-1100 during flower. Certain things to consider when mixing nutrients, 1st what’s the PPMS of your water supply then factor that in. It’s a crap shoot without this piece of equipment :love_you_gesture:

I’ve been using the Jacks 321 for about 2 weeks. My soil got down to 800 or so 2 weeks ago so I started using the nutes then. They usually hang around 800-1000. I have been feeding everytime since that’s the reason I went with Jacks was everyone on the forum said you can feed everytime. I’m thinking it is the PH issue since my ppms are close, today when I checked I mean it was 850 but just must not be absorbing the ones I need ( I have been using the vivosun TDS meter)

1 Like

Right on Grow Bro :love_you_gesture:

I’ll flush in a day and also going to try and find some dolomite lime tomorrow. Thanks for the help I appreciate it

When had problems with it was ph imbalance???

Also humidity high then low and versa