Hi i have been experiencing some rusting on my auto flower im a new grower so its hard for me to identify deficiencies and Diseases wondering is i could get some help the white stuff if milk i was told that it can act as a natural pesticide and mildew repellent
Rusting
- Thread starter Bmoney
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Emilya Green
Well-Known Member
this is neither a mold, mildew or a pest, so milk is not going to help. This looks very much like a common magnesium deficiency, and can be kept in check by applying calmag every other watering.
Barney86
Well-Known Member
Yeah I'd say mag def too mate.
Check the ph of the media first though cos if that's off then that would be the reason for it. Is that soil or coco?
Check the ph of the media first though cos if that's off then that would be the reason for it. Is that soil or coco?
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Emilya Green
Well-Known Member
ah, then that is the problem. You have misunderstood the pH thing a bit. You are correct that FFHF is buffered to be at a pH of 6.7 or so when dry... that is the base pH of that soil.
The usable range of pH in soil is 6.2-6.8. Some elements are most mobile at the low end of this range and most near the middle of the range at 6.5. Magnesium is most mobile at the low end of the scale.
You should always adjust your pH on incoming fluids to 6.3 pH. This mathematically is the point where the most nutrients are the most mobile. Visualize the container of soil that has been saturated (it can hold no more water) at a pH of 6.3 pH. You essentially now have a column of water or water/nutes, that by weight has taken over the pH of the container, and at that moment the pH has no choice but to be the pH of the liquid suspended there, at 6.3 pH.
Here is where the base pH of the soil comes in. The buffers in the soil are trying to convert the 6.3 pH of that column of liquid to a higher pH, so immediately after watering the pH of that column begins to drift upwards. Also, as the level of the water table begins to fall as the plant uses up some of that water, the soil above the column of water begins to dry out. As it dries out, it loses the influence of the 6.3 and drifting water, and the pH of that dry region begins to approach the base pH of the dry soil.
With you watering at 6.6-6.8, you have already missed the lower part of the soil pH range, between 6.2-6.6 pH. This is why you are not able to pick up the magnesium you are supplying... your pH is not moving though the entire range. Adjust from now on to 6.3pH, and continue the same nutes and calmag you have been using, and I bet that all the problems will clear up.
By the way, and sorry I didn't already do this, but Welcome to the Forum!
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- #6
This needs to be stickied somewhere.ah, then that is the problem. You have misunderstood the pH thing a bit. You are correct that FFHF is buffered to be at a pH of 6.7 or so when dry... that is the base pH of that soil.
The usable range of pH in soil is 6.2-6.8. Some elements are most mobile at the low end of this range and most near the middle of the range at 6.5. Magnesium is most mobile at the low end of the scale.
You should always adjust your pH on incoming fluids to 6.3 pH. This mathematically is the point where the most nutrients are the most mobile. Visualize the container of soil that has been saturated (it can hold no more water) at a pH of 6.3 pH. You essentially now have a column of water or water/nutes, that by weight has taken over the pH of the container, and at that moment the pH has no choice but to be the pH of the liquid suspended there, at 6.3 pH.
Here is where the base pH of the soil comes in. The buffers in the soil are trying to convert the 6.3 pH of that column of liquid to a higher pH, so immediately after watering the pH of that column begins to drift upwards. Also, as the level of the water table begins to fall as the plant uses up some of that water, the soil above the column of water begins to dry out. As it dries out, it loses the influence of the 6.3 and drifting water, and the pH of that dry region begins to approach the base pH of the dry soil.
With you watering at 6.6-6.8, you have already missed the lower part of the soil pH range, between 6.2-6.6 pH. This is why you are not able to pick up the magnesium you are supplying... your pH is not moving though the entire range. Adjust from now on to 6.3pH, and continue the same nutes and calmag you have been using, and I bet that all the problems will clear up.
By the way, and sorry I didn't already do this, but Welcome to the Forum!
The most clear explanation of phing water vs buffered soil medium i think I’ve ever read.
Emilya Green
Well-Known Member
Thank you for that... I don't know how many times I have explained this on here... I am starting to get pretty good at stating my point.
Welcome. Glad you had help for your problem.
