Cal Mag deficiency?

I’m afraid I have a calcium and magnesium deficiency.

I was ignorantly using reverse osmosis water thinking I was keeping it clean and of course flushed all the calcium and magnesium out of the soil. Purchase a bottle of Cal Mag gave one dose thus far…

What’s my best move now?? Thanks for your help.

1 Like

Keep dosing per the package. How about you fill out one of these and maybe an overall picture in natural light?

COPY/PASTE the below list into your forum post.

Answer these simple questions the best you can.
If you do not know, or do not use something; Just say so; Or post
NA (non applicable)

  • What strain, Seed bank, or bag seed
  • Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF
  • Vessels: Pots, Grow beds, Buckets, Troths
  • PH of Water, Solution, runoff (if Applicable)
  • PPM/TDS or EC of nutrient solution if applicable
  • Indoor or Outdoor
  • Light system
  • Temps; Day, Night
  • Humidity; Day, Night
  • Ventilation system; Yes, No, Size
  • AC, Humidifier, De-humidifier,
  • Co2; Yes, No

Always try to upload a clear picture of any issues you may have to allow the community to assist you.

Add anything else you feel would help us give you a most informed answer should be included. Feel free to elaborate, but short and to the point questions and facts will help us help you in a more efficient manner :slight_smile:

1 Like

Thank you. I am working on filling out the questions now. Should I cut the damage leaves off the Autoflower or leave them?

Leave, they still serve purpose

1 Like

I’em sure I know what is going on here with your plants. But I need a pic in natural light please

1 Like

Northern Lights Auto week 5

Thank you for the perfect light

Nutrient Burn
Please look for the fix below


What makes you think it’s nutrient burn versus calcium or magnesium deficiency? I have been using reverse osmosis water and I’ve done a flush twice. Once because it was time. And once because I gave too high pH of water. I’m feeding with Fox Farm not at full strength.
Growing in organic soil 5-gallon pots.
I appreciate you time thank you

Hey Ben,
I want to welcome you to ILGM and to our awesome community.
Any way it’s pretty easy MAGNESIUM looks like this>>>


Neither one look close to what’s going on with your plants that’s why I think isn’t one of them.
Different strains of marijuana will react differently to nutrients.
You’ll have to cut back even more for that plant

1 Like

Thank you for taking the time to help.
I will cut back even more on the nutrients. Do you think I should flush the plants?
How often should I be feeding and watering them? they’re in 5-gallon pots growing in soil.
I water whenever the top inch of soil is dry, and the pot feels lighter.
Thanks again

I flushed with 6.2 pH water 400 PPM. What came out was 6.8 pH water and surprisingly only 660 PPM.
I’m honestly not sure what to do. I want to get the ppm’s up around a thousand and keep the pH around what? 6.5 6.2. This is just what I think I don’t know if I’m right.
It’s been a great resource I appreciate your time

Hi @Ben, Deficency and toxicity can look the same and have a root cause for both sometimes. Im not a pro, but I follow a few simple rules prescribed by the good people here when I had the same issue. I caught it early on. I did a ph’d water flush while checking my soil runoff with a soil ph meter. My soil at the time was in the low 5’s so the plant wasnt able to uptake anything. I then cked my ppm runoff and it was over 2000 ppm. The flush got the soil back to 6.5 and then I fed her the day after with a low dose of nutes 400ppm. And then upped the ppms every other watering around 200 ppms till things stabilized and got back on the nute schedule. Always stayin at around 1000ppms goin in and comin out. Sometimes every other watering is still too much nute but if you keep to 1/4 of the dose recommened and build from there as you pay attention to the leaves you’ll be able to amp up the nutes. Mine stopped spreading quickly after the flush. Not sure what stage your in but I found I didnt have to add any nutes to the FFoF till it went to flower. At that time most of the nutes in the soil had washed out of the pots. I used the FF trio of nutes from there starting when I flipped to flower and then stopped the grow big 2 weeks after I saw the first pistils. I flushed again 1 week after pistils starting turning orange with Sledgehammer and Ph’d water. (PIA) …then two weeks of just water. (I now add Terpenes every watering till the last week).
Hope this helps. All the best!


Hi abouttime, read your post, saying you flush with sledge hammer, I am thinking I need to do a first flush, I have sledgehammer to use but I’ve been hearing good and bad things… I’m in a 32 gal smart pot, with scrog, and cannot run 300 gals of water LOL … just looking to see how it went , will you use it again? Did it mess with your plants? Just don’t want to screw up.

1 Like

Hi @Teacherttom1, I didnt have a problem with it all. I did a regular water flush in the 4/5 th week because of low ph and calmag deficiency,.Then at 2 weeks prior to harvest, I mixed the sledgehammer as directed for dosage and phd that water and flushed again…If your working with a big pot such as yours. I would make sure you have good drainage at the bottom of the pot. In other words dont let it sit in water. If you let the water simply drain away from the pot, you’ll be doing semi flushes when your watering anyway. Towards the end of your grow most of the soils nutes have been used up so adding nutes once a week during flower is needed. Hence a good ppm meter to tell you what your putting in and whats coming out in the runoff will tell you how much nute is in your soil. Check your ppms in the runoff while flushing and you’ll see the ppms falling as you keep pouring water thru and check periodically while doing it. Get it down to 200-400ppms at 2 weeks from the finish according to the genetics of the plant and you’ll be fine with straight water till the end. Even the sledgehammer will be flushed out by then.
Anytime I can help please reach out and keep me posted on your grow.
Puff puff pass!

Well it’s about time … lol Your handle to way cooll Any way looks as if you got this …

Thank you B Safe

1 Like

Thanks @garrigan62, yeah it works…it was to me… “about time” I grew my own!!!.. And growing it, as you know, is is “about time”!
Hope all is well by you!

1 Like