Fertilizing Trees & Shrubs

Fertilizing Trees and Shrubs

Paul Schnare

Saturday, April 5, 2003

Most people are well aware of the need to fertilize lawns in the spring, but they forget about their trees and shrubs.  Trees and shrubs will adapt to the environment in which they are placed.  But in order for them to grow vigorously, they should be fertilized every spring, and early fall (azaleas, rhododendrons and roses, among others, are exceptions).

Fertilize now because most trees and shrubs will be putting on their annual flush of growth at this time.  Available nutrients are needed for this growth spurt.

Fertilize early in the fall, because trees and shrubs are going through major changes in order to go into dormancy.  Again, available nutrients will aid in this transition.

Fertilize most flowering trees, shade trees and shrubs with a fertilizer like 19-8-10 with micronutrients.  The easiest way to handle this material is to spread it around the drip line of trees and under shrubs.  Either water it in after application, or wait for a rain.

You can also punch holes in the soil under the drip line and then fill the holes with the 19-8-10.   This would be similar to placing fertilizer spikes in the soil.  I don’t recommend this method because large quantities of fertilizer in one place may burn roots—something you don’t want to do when fertilizing.

Plants that are growing vigorously have greener and larger leaves.  Their growth rate is increased both in terms of stem elongation and in terms of stem girth.    Their root systems are usually larger than unfertilized trees and shrubs.  In addition you will find that vigorously growing plants are less susceptible to insect and disease problems.

A small investment in fertilizer for your trees and shrubs will pay big dividends.  Plants looked healthier and require fewer applications of sprays to eliminate disease and insect problems.