Evergreens (Conifers)

Evergreen conifers — including pine, spruce, fir, arborvitae, and juniper — have fundamentally different nutritional needs than deciduous trees and most garden plants. Because they retain their needles year-round, evergreens never go through the massive nutrient mobilization cycle that leaf-dropping trees experience each fall and spring. This means their fertilizer requirements are generally lower and more consistent. Nitrogen is the primary growth driver for evergreens, responsible for the deep green needle color that defines their landscape value. However, conifers have an unusually strong relationship with mycorrhizal fungi — beneficial soil organisms that dramatically extend the root system's ability to absorb phosphorus and micronutrients. Excessive phosphorus fertilization actually disrupts this mycorrhizal partnership, which is why the best evergreen fertilizers keep the middle NPK number relatively low. Potassium plays a critical role in winter hardiness, helping cells resist freeze damage during New England's harsh winters. The single most important factor in evergreen nutrition is soil pH. Most conifers thrive at pH 5.0-6.5, and their ability to absorb iron, manganese, and zinc drops sharply as pH rises above 6.5, leading to chlorosis (yellowing needles) even when these nutrients are abundant in the soil. New England's naturally acidic soils are generally favorable, but construction disturbance, lime-leaching from concrete foundations, and years of hardwood leaf mulch can push pH above the comfort zone for many conifers.