If you live in a dryer climate, you've probably experienced the frustration of fertilizing a tree or shrub only to see little improvement weeks later. The problem isn't usually the fertilizer itself—it may be how difficult it is for nutrients in that fertilizer to reach the root zone.
Many fertilizer products instruct homeowners to "work into soil and water". That sounds simple enough unless your landscape is covered with decorative rock. Working fertilizer into the soil would mean moving the rock aside, working around drip irrigation tubing, and spending far more time than expected on a routine gardening task.
Even if the fertilizer were applied per the instructions, another challenge remains: water.
Granular fertilizers depend on water to dissolve and carry nutrients deep into the soil where roots can absorb them. In many arid regions, rainfall is infrequent and often too light to thoroughly move nutrients into the root zone. As a result, fertilizer granules can remain at the surface for weeks or even months – perhaps never reaching optimal depth in the soil.
While fertilizer sits exposed, some nutrients may be lost before plants can use them. Nitrogen sources in the fertilizer escape into the atmosphere when left on the rock/soil surface, particularly during hot, dry weather. UV rays can reduce the effectiveness of nutrients that were intended to feed your plants. And, a heavy rainfall can wash away fertilizer (contributing to urban stormwater pollution) instead of helping it to enter the soil.
The result? You spend money on fertilizer, invest time applying it, and your trees and shrubs may receive only a portion of the nutrients you intended.
For homeowners with rock-covered landscapes and drip irrigation systems, the most effective fertilization methods are those that deliver nutrients to the root zone where plants can access them directly. When nutrients are carried below the surface, they are protected from sun exposure, less susceptible to loss, and positioned where roots can put them to work.
Healthy plants need nutrients—delivered where they can absorb them.