Fertilizer spikes are pre-measured, solid nutrient delivery systems designed to offer plants a consistent supply of food beneath the soil surface. These concentrated sticks simplify feeding trees, shrubs, and deep-rooted plants. This guide provides an overview of why these tools are effective and how to use them correctly to ensure sustained plant health.
Why Choose Fertilizer Spikes Over Other Methods
The advantage of fertilizer spikes lies in their precision feeding directly into the plant’s root zone. Unlike broadcast granular fertilizers that spread nutrients across the topsoil, spikes deliver several inches below the surface, placing them near the active feeder roots. This targeted approach ensures the plant absorbs the majority of the nutrients with minimal waste.
Spikes utilize a slow-release mechanism, providing a steady supply of nitrogen, phosphorus, and potassium over several months. This continuous feeding contrasts with the rapid nutrient flush provided by liquid fertilizers, which often requires more frequent application. The solid form of the spike must be broken down by soil moisture and microbial activity, which naturally regulates the release rate.
This controlled release significantly reduces the risk of nutrient runoff and leaching. Because the fertilizer is locked beneath the surface, it is less susceptible to being washed away by rain or irrigation. This method also minimizes the chance of over-fertilization, which can cause leaf burn or root damage from excessive salt concentration.
Step-by-Step Installation Instructions
Ensure the soil is soft and moist before installation; this makes insertion easier and helps initiate nutrient dissolution. Gather the necessary tools, including the fertilizer spikes, a plastic cap (often provided with the spikes), and a hammer or mallet for driving the spike. Always wear appropriate eye protection before striking the spike.
Place the plastic cap over the top of the spike to protect it from the hammer’s impact and prevent it from splintering. For hard or compacted soil, first create a pilot hole using a sturdy metal rod or a section of rebar. This technique prevents the spike itself from breaking during the insertion process.
Drive the capped spike into the ground until the top is approximately two inches below the soil surface. Complete coverage ensures the spike is underground, feeding the roots and avoiding surface obstruction. Once the spike is fully inserted, remove the plastic cap and cover the hole with the displaced soil or mulch.
Immediately after installation, thoroughly water the area to activate the spike’s slow-release mechanism. This moisture begins the dissolution process, allowing the nutrients to start moving into the surrounding soil.
Determining Optimal Placement and Application Schedule
The ideal placement for fertilizer spikes is along the plant’s drip line, which is the circumference on the ground directly beneath the outermost tips of the branches. The feeder roots responsible for nutrient absorption are most concentrated in this zone, making it the most efficient area for spike placement. Avoid placing spikes too close to the main trunk, typically within a 30-inch radius, as this area has fewer feeder roots and can increase the risk of damaging the main root flare.
To determine the number of spikes needed, consult the product instructions, which often base the count on the tree’s trunk diameter or the shrub’s height. For instance, a common guideline for trees is one spike for every one or two inches of trunk diameter measured one foot above the ground. Evenly space the calculated number of spikes around the entire drip line to ensure a balanced distribution of nutrients to all parts of the root system.
The recommended application schedule for most trees and shrubs is twice a year to maintain consistent nutrition. The first application should occur in early spring, just as the plant is breaking dormancy and beginning its active growth cycle. The second application is best performed in late fall, after leaf drop but before the ground freezes, allowing roots to absorb nutrients that aid in winter hardiness and support spring growth.