Not saying I know very much but.
Ive been growing since 1972. Both organic, and chemical.
Right now the fertilizer, and feeding schedule is done by using a company that has been making....PLANT SPECIFIC FERTILIZER since 1965.
The formula can vary "Slightly" Some may need added Iron, and Mg Sulfate/Epsom Salts.
They have concluded 19.5-20-39 , with added Trace Minerals, and Mg Sulfate in the proper ratios of course... is the right ratio of NPK ect for marijuana. This is going by Tissue Analysis.
The Base Formula is 4-20-39
Then you add 15.5-0-0 ( Calcium Nitrate ), and then Epsom Salts. = 19.5-20-39. Weed is also very K hungry, and likes 2x K vs Nitrogen.
K is also Very important for Terpene formation, immune function, and pest resistance. Most stuff is way to low in K.
Bottom line is, is to not overdose them during the whole grow ect, and give them only what they need. If you do this, there is no need to completely eliminate any 1 fertilizer. Just the PPM are cut back.
If youre growing in soil, using livng soil, ya cat flush ect. No need for it.
There is a complete feeding guide they used to have on their site, and we go by this instruction.
From seedling-finish they get a certain amount of fertilizer.
And YES, of course Sulfur is very, very important.
Mg Sulfate is very important for Terpene Production.
Magnesium is the #1 Container Deficiency, and marijuana is a Very Hungry Mg Sulfate consumer.
For an 8 weeks flowering strain all nutrients are increased slightly every week.
We up the Monopotassium Phosphate, in weeks 3-4 after light flip, while at the same time, again increasing PPM of base 19.5-20-39 feed, and Epsom Salts...
In weeks 5-6, we drop the NPK, but still "Slightly" increase base formula, but go heavier on Epsom Salts.
In weeks 7-8 feed schedule is backed off, but never drops any 1 nutrient.
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