When and How to Fertilize Established Trees
title: "When and How to Fertilize Established Trees"
Most established trees in home landscapes don't need fertilizer. That statement contradicts the marketing on bags of tree fertilizer spikes, and it contradicts the advice from some nurseries, but it reflects the consistent finding of university tree research.
A healthy mature tree in a lawn that is regularly fertilized is already receiving nitrogen from lawn fertilization. A tree with adequate soil organic matter recycles nutrients through leaf litter and root decomposition. Fertilizing a healthy tree adds nitrogen it doesn't need, pushing vegetative growth at the expense of defensive compounds and structural wood density.
The case for fertilizing is real but specific: nutrient-deficient trees, trees in poor urban soils stripped of organic matter, trees recovering from defoliation or transplant stress, or trees diagnosed with a specific nutrient deficiency by soil or tissue test.
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Table of Contents
- Do Established Trees Need Fertilizer?
- Signs of Nutrient Deficiency
- Soil Testing Before Fertilizing
- When to Fertilize Trees
- How Much Fertilizer to Apply
- Application Methods
- Fertilizer Types
- Frequently Asked Questions
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