"What are the ingredients in Miracle-Gro Singles?
Ingredients. Guaranteed Analysis: Total Nitrogen (NI) (24): Ammoniacal Nitrogen (3.5%), Urea Nitrogen (20.5%), Available Phosphate (P2O5) (8%), Soluble Potash (K2O) (16%). Derived from: Ammonium Sulfate, Potassium Phosphate, Potassium Chloride, Urea, Urea Phosphate."
There is no indication of how much chloride or urea. I think your plants are large enough that the urea won't be a problem. If there is too much chloride, then your tobacco may be fireproof.
Bob