Soils with a pH below 7 are acidic while those above 7 are alkaline. Soil pH is measured on a scale of 0 to 14. Soil pHĪ fertility program for woody plants begins with obtaining an analysis of soil pH (or level of acidity).

Proper maintenance of soil fertility and attention to plant nutritional requirements is at the heart of an effective IPM or Plant Health Care program. These practices might include incorporating compost into soils at the preplant stage, applying organic mulches, and cover cropping. A program of cultural practices that sustains or replenishes soil organic matter and nutrients should also be established. In landscapes and field nurseries, it is important to select species that are best suited to the site. For these reasons, periodic applications of fertilizer to the soil beneath ornamental trees and shrubs are sometimes needed to replenish essential mineral elements and to promote healthy growth. Soils may be vastly different from those of the native habitat of a given plant, and nutrient recycling systems may be altered or diminished as a result of planting schemes (planting in turf areas) or maintenance practices (collection of fallen leaves). Nursery, street tree, and landscape plantings are, for the most part, an artificial habitat. This is due not only to the natural recycling of nutrients that occurs in nature, but also to the fact that plants in the wild typically grow only where they are best adapted or have a competitive advantage. Trees and shrubs growing in their natural habitats rarely display symptoms of nutrient deficiency.

Water insoluble liquid fertilizers