Possible Magnesium Deficiency


#1

I think I may have a magnesium deficiency, but I want to make sure. The middle and lower leaves are beginning to turn yellow with green veins. New growth does not appear to be changing this color. Using Dr. Earth Pot 'o Gold with a bit of bone meal(6-8-0), blood meal(12-0-0) and dr.earth vegetable fertilizer (5-7-3). I added a bit of epsom salt (1 teaspoon diluted in 1 gallon of water and I poured about a quarter gallon) today as well. Any suggestions? Thanks!


#2

Actually I’m seeing signs of nutrient toxicity and or maybe nutrient lockouts.

What is the pH of the water you use?

And you are giving it a ton of nitrogen and not enough potassium. We also could know what the nutrient concentration is by measuring the EC/PPM in the soil. Usually monitoring/measuring some of the run-off after watering will keep you out of trouble.

If you don’t have a digital EC tester pen, or a TDS pen, I highly recommend getting one and you can get them for very little, only about $10 online at places like amazon and you can get a pH pen there too:
TDS:


pH meter:

And you can read about another way to test your soil here:


#3

Thanks MacGyver, I’ll pick up a PH/TDS meter when I stop at home depot tomorrow. I thought that I was a little high in Nitrogen, and to be honest until yesterday it was just the bonemeal and dr.earth, combined for an 11-15-3. I added the bloodmeal yesterday because I kind of panicked when I noticed the yellowing wasn’t going away (it started maybe 5 days ago). I’ll get back to you once I test my soil/water ph, although I think their okay as my other two plants are not exhibiting these fluctuations in color. For future reference, should I stay away from high nitrogen supplements like bloodmeal? Thanks again


#4

EC/TDS/PPM and pH are not the same thing and I’m not sure you can find digital pens as in the two links above for anywhere near as affordable of a price at Home Depot.

If you are so sure it will be ok, and you are giving this plant basically the same thing as the others, why does this one have problems and not the others?

I’m guessing all your plants are on the verge of showing you problems and this one showed first and then maybe you added too and accelerated the problem by even upping the nutrient toxicity with more nutrients.

This is why you need to know not only the pH that can change in each individual container, but also monitor the build up of nutrient salts by monitoring the overflow/run-off after watering or as described as in the blog link by Robert.

Another thought…Over watering, or having the soil too wet for too long will also often cause symptoms that can appear like a magnesium deficiency.

Nothing wrong with bloodmeal if used correctly.

Overall NPK values should be more balanced, more similar to what you would feed tomatoes.


#5

MacGyver, you were correct, I could not procure one from HD today. I’m ordering the pH and TDS pen today, hopefully they arrive in time to save my plants.

You were also right as one of my other plants has began to exhibit similar discoloration today.

I don’t think that I have been watering too much, but if I have been and let the soil dry out a little, will my plants regain their vitality once again?

Thanks for all the help thus far by the way. I’ll let you know the results of my pH and TDS tests once I have them.


#6

As I said, I don’t think it is a magnesium deficiency. So letting the soil dry enough between watering or feeding, as you should be doing anyway, probably won’t add any noticeable improvements, especially if you haven’t been over-watering in the first place.

Are you just using plain tap water on your plants? If so, this is probably a significant part of the problem. Most tap water has a pH of about 7.5 and is often very hard, if you have limescale, your water is hard, and those extra “lime scale” minerals will cause pH problems in your soil after awhile, especially if the TDS is really high. An EC around or above 0.2EC, or a total dissolved solids in parts per million in the USA scale of around or above 100PPM will likely cause you problems, especially if these things are not being monitored in the soil.

I suspect, you are going to find the PPM in your water to be at least a little too high and around a 7.5pH, and i suspect you will find the EC/TDS/PPM in your soil to be a bit high as well as the pH not being quite ideal.