The blooming trees and flowers that accompany the onset of spring signal the beginning of pollen season, which should last several weeks, Bardon says. He predicts most regions in North Carolina can expect a pollen season similar to last year's. The amount of pollen varies widely within local areas and among geographic regions. Dry weather, nearby construction, or a group of neighboring trees competing for light, water and nutrients in the soil, can put a particular tree under stress and cause it to feel threatened. The tree reacts by trying to reproduce itself.
Pollen is a byproduct of the reproductive process.
The mix of trees among the state's distinctive regions accounts for differences in the amount of pollen produced. The mountains have more hardwoods than pines, the coast has more pines than hardwoods, and the piedmont has a mix. Other factors affecting pollen production include a region's elevation, latitude and distance from the coast.