Before you plant in a new site, test the soil. The soil test will determine the soil's phosphorous and potassium levels, the pH and the soluble salts content. Adjust these as needed before you plant and then retest every five years. If your soil needs phosphorous, potassium, calcium or sulfur, incorporate them thoroughly into the future root zone before planting. These nutrients will not move into the root zone if applied only to the soil surface.
Micronutrient deficiencies vary geographically.
Check with county extension staff for guidelines in your area. Use foliar appearance as a guide to nitrogen requirements. To prevent lodging, flopping or the need for staking, keep soil nitrogen levels low. However, if a leaf blade isn't a normal green color, nitrogen or a micronutrient may be needed. Unsatisfactory foliar color could also indicate low soil oxygen levels, inadequate drainage or excess watering.