If the soil is properly prepared prior to planting, only nitrogen fertilizer is required on a routine annual basis. Do not fertilize in the first year since the root system is very susceptible to root burning at this stage. In subsequent years, always fertilize with ammonium sulfate in March or April. To each plant, apply 4 ounces of ammonium sulfate in year two, 5 ounces in year three, 6 ounces in year four, 7 ounces in year five, and 8 ounces in year six and subsequent years. Retest the soil every 5 years or so to make sure that the soil pH is in the correct range. If nutrient deficiency symptoms (e.g., light-green or red leaves in the summer, poor growth, poor yield) appear, it is likely that the soil pH is no longer in the optimum range of 4.5 to 5.0.