Best Practices for Tree Fertilization
Fertilizing trees can be an important part of landscape care—but only if it’s done correctly. Many homeowners over-fertilize or fertilize at the wrong time, which can do more harm than good. This guide will help you understand when, why, and how to fertilize your trees for long-term health.
1. Know When Fertilization Is Needed
Not all trees need fertilizer. Signs your tree might benefit include:
Poor growth or sparse foliage
Pale or yellowing leaves (chlorosis)
Dead branch tips or reduced leaf size
Pro Tip: A soil test is the best way to determine nutrient deficiencies and avoid guesswork.
2. Choose the Right Fertilizer
Look for a balanced, slow-release fertilizer with a ratio like 10-10-10 or one tailored to your soil test results.
Nitrogen (N) promotes green growth
Phosphorus (P) supports root and flower development
Potassium (K) strengthens disease resistance
Avoid high-nitrogen lawn fertilizers near trees, as they can encourage weak, fast growth.
3. Timing Matters
The best time to fertilize is:
Late winter to early spring, before new growth begins
Late fall (in some cases), to strengthen roots before dormancy
Avoid fertilizing in midsummer or drought periods—it can stress the tree or stimulate growth at the wrong time.
4. How to Apply Fertilizer
There are a few common methods:
A. Broadcast Method
Apply dry fertilizer evenly over the root zone (not just at the trunk)
Water thoroughly after application
B. Soil Injection or Deep Root Feeding
Used by arborists to inject nutrients directly into the soil
Ideal for compacted or nutrient-poor soils
C. Fertilizer Spikes or Stakes
Convenient but can lead to uneven nutrient distribution
Use as directed and space evenly
5. Avoid Common Mistakes
Don’t over-fertilize – It can burn roots and pollute waterways
Don’t fertilize newly planted trees – Wait 1–2 years until they’re established
Don’t apply near trunk – Keep fertilizer at least 6"–12" away
6. Healthy Soil First
Fertilizer is not a substitute for poor soil or bad planting practices. Prioritize:
Organic mulch to enrich soil over time
Proper watering, especially in dry spells
Aeration if soil is compacted