How Much Water Do Sunflower Plants Need?

Watering

• Growing sunflowers need approximately 0.15 inch of water a day, while fully-grown sunflowers need double that, according to horticulturalists at Kansas State University Cooperative Extension. While they are drought tolerant and prefer dry conditions, they can't withstand long dry spells.

Soil Drainage

• To avoid rotting in too much water, sunflowers need to grow in well-drained soil. This allows gardeners to water them more frequently without having to worry about the plants becoming water logged.

Tips

• Kansas State University recommends drip irrigation rather than overhead watering. Splashing water on the flowers can damage their petals. Frequent, light watering tends to promote growth most successfully. If leaves turn yellow or start to drop, it usually is a sign that they need more water.