Fertilizing Established Magnolias and Firs: Less Is Usually More

Large, established magnolias and firs rarely need supplemental feeding—especially if they're growing near a fertilized lawn. Their extensive root systems mine nutrients from a vast soil volume. But if foliage looks paler than similar trees nearby, a targeted approach beats guesswork.

Start with a Soil Test

Before applying anything, submit a sample to your state soil testing lab. It's inexpensive, precise, and tells you exactly what's missing—preventing waste and potential harm from unnecessary nutrients.

If You Must Act Now

As a general guideline for established trees in the absence of a soil test: broadcast 2 cups of 10-10-10 fertilizer per 100 square feet of canopy coverage area. Apply in fall after leaf drop or early spring before bud break—never in summer heat or late fall when it could stimulate tender growth.

Key Reminders

• Mature trees in lawns often get plenty of nitrogen from turf fertilization
• Over-fertilizing stresses trees more than under-fertilizing
• Mulch rings out to the drip line do more long-term good than fertilizer

Feed the soil, not just the tree—and let a soil test be your guide.