Starter fertilizer is a product with a blend of the macro nutrients nitrogen, phosphorous and potassium in a ratio ideal for kick-starting strong root development in seedling plants. According to Pennsylvania State University, the ratio of macro nutrients that is desirable depends on the type of crop, climate and the quality and quantity of nutrients already present in the soil. Soil with already high fertility will likely not require starter fertilizer. The key purpose of starter fertilizer is to place the nutrients very near the nascent root system where they can easily be absorbed and metabolized.
Capture a soil sample from the planting area to determine the existing nutrient levels. Fill the container that comes with a commercial soil test kit with the recommended amount of soil and mail it in for analysis. Alternatively, place roughly a cup of soil into a resealable plastic bag and take the soil for testing at a local nursery or local university agricultural testing service.
Consult the soil test findings to determine the nutrients that need to be added into the soil by your starter fertilizer. Select a fertilizer product with the ratio of macro nutrients and any necessary micro-nutrients that will create the optimal growing conditions for your type of plantings.
Hand cast or use a walking spreader to place the fertilizer into a well-prepared planting bed so that an even thin layer of fertilizer rests either 2 inches below where the seed will be planted or 2 inches beside where the seed is or will be planted.
Apply the starter fertilizer according to the product label dosing directions but do not exceed a rate of 150 pounds of fertilizer for every half acre of planting. Common use rates fall between 50 pounds per half acre and the maximum 150 pounds per half acre. Always err on the side of less fertilizer, not more.
Water side-applied starter fertilizer very gently into the soil to wet it and keep it from blowing away, but being careful not to wash all the applied nutrients out of the seedling root zone by flooding the soil. Cover fertilizer applied under the seeds with 2 inches of the tilled and prepared soil.