Identifying Black Balls in Potting Soil: Fertilizer or Pest?

Likely Slow-Release Fertilizer Prills

Squeeze a few—if they release liquid, they're fertilizer pellets. Common in commercial mixes.

Most tropicals need weekly to monthly feeding during growth.
Visit a local garden center (not big-box) with a sample for product recommendations.

Black balls are not pests—just spent fertilizer.

House Plants: Custom Potting Soil Recipes for Different Plant Types; Top Flowering Plant for Nursing Home: Kalanchoe; Sudden Wilting in Ivy and Radermachera: Root Rot Is the Prime Suspect; Eliminating Fungus Gnats from Houseplants Without Pesticides; Eliminating Fungus Gnats from Wandering Jew Plants; Tiny Black Flying Gnats: Fungus Gnats from Overwatering or Rotting Produce—Eliminate by Drying Soil; Gardenia Bud Drop: Too Wet, Too Dark, Too Cool—Fix the Trio; Golden Pothos Care: Fixing Yellow Leaves and Soil Mold; Indoor Herb Seedlings: Leggy, Falling Over, Dying; Beginner's Guide to Watering and Repotting Spider Plants

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