While proper drainage is crucial for plant health, it's absolutely possible to overwater plants even in urban planter boxes with drainage holes. Drainage helps prevent waterlogging, but it doesn't eliminate the risk of overwatering entirely. When you water too frequently, the soil remains constantly saturated, depriving plant roots of essential oxygen. This creates an environment where roots can't breathe, leading to root rot—a serious condition that can kill your plants.
Signs of overwatering include yellowing leaves, wilting despite wet soil, and mold growth on the soil surface. The soil might also develop a foul odor, indicating anaerobic conditions. Even with drainage holes, compacted soil or poor-quality potting mix can retain too much moisture.
To prevent overwatering, always check soil moisture before watering. Insert your finger about two inches into the soil; if it feels moist, delay watering. Ensure your planter boxes have sufficient drainage holes and use well-draining potting mix. Consider the specific water needs of each plant species and adjust your watering schedule according to weather conditions—plants typically need less water during cool, cloudy periods.
Remember, drainage helps excess water escape, but it's your watering habits that ultimately determine whether your urban plants thrive or struggle with too much moisture.