These organic fertilizer spikes, specially formulated for trees and shrubs, help build a nourishing environment that promotes beneficial microbial action where trees and shrubs need it most – at the roots. This “in-the-ground” feeding is the most efficient delivery system for organics. The spikes improve long-term soil quality by promoting beneficial microbial growth. The pre-measured spikes make for fast, easy and mess-free fertilizing. For best results, apply in early spring and late fall.