aruzinsky

I don't know how much is too much because I never tried to do it. In general, I fertilize outdoor plants with a solution of soluble fertilizer 1 to 2 tbs./gal. or 1 to 2 pounds in a 32 gallon plastic trash can of water. If and when the plant grows fast, I repeat.

But, at this dilution, a fertilizer that is high in urea, will temporarily stunt a plant. Plants better tolerate high concentrations of nitrates than urea, but, a small amount of urea stimulates growth in ways that nitrates can't. I recommend fertilizer that is 10% to 20% urea. In my experience, at 1 tbs./gal. for ground plantings and 1 tsp./gal. for potted plants, 10-20% urea stimulates growth as no other form of nitrogen can.

Most soluble phosphates do not penetrate soil well, especially clay soils. When such phosphate solutions are applied to the soil surface, the phosphates stay near the surface until the soil is tilled. For that reason, when I fill a planting hole, I alternately fill the hole with fertilizer solution and soil, in, maybe, 3-5 steps. That way, phosphates will be in the vicinity of the roots. That worked especially well with the old 15-30-15 Miracle-Gro which you can't get anymore. I said "most soluble phosphates" because I strongly suspect that urea phosphate is an exception, i.e., it will easily penetrate soil, because it is covalently bonded.