Sunflowers require a moderate amount of water. Often, consistent and steady watering is important, as the plants will need to establish deep roots in order to support the foliage and heavy flower heads. Sunflower plants need at least an inch of water per week, either from rainfall or irrigation.
When irrigating sunflowers, it’s best to apply water slowly and deeply so that excess moisture isn’t running off or pooling around your plants. The ideal time for watering is during the morning hours before noon; this allows any remaining moisture on the leaves to dry during the day, reducing the risk of fungal disease and mildew.
When sunflower blooms begin dying back and petals are dropping, stop feeding or distributing additional fertilizer or water until it’s time for fall cleanup. Instead, allow sunflowers to gradually dry out as they reach their maturity stage—it’s an indication that flowering has been completed.
Overall, too much water can be just as detrimental to a sunflower’s health as too little water – both situations can lead to drooping foliage and stunted growth. Pay attention to your soil type when establishing your watering routine: sandy soils may require more frequent irrigation than clay-rich soils, which hold far more moisture than sandy soils do.