There is no way to tell what fertilizer products are appropriate w/o a soil test to first determine what nutrients are lacking. W/o the benefit provided by a soil test, you're playing a guessing game. Since a toxicity (excess) is as likely to be limiting as a deficiency, there is roughly the same potential for the application(s) to be limiting as beneficial. If you feel it's essential to provide supplemental nutrition w/o benefit of a soil test, and since nitrogen is most commonly the scarcest nutrient in landscapes, it would make better sense to apply a high nitrogen lawn fertilizer than any other product - something with (by weight) 25-35% nitrogen, no phosphorous (seldom deficient in landscapes), and 3-10% potassium.
Too, there are many factors that determine how well a plant holds onto its fruit - temperatures, light levels, water availability, number of fruits set, etc.
Al
