• Once established, they will tolerate some drought. However, in the periods before, during and after flowering, they perform best with deep, regular watering.

Fertilizing

• In most cases, they will not need fertilizer. However, if your soil is very poor you can use a slow-release granular fertilizer to encourage larger flowers. Be careful - too much nitrogen can inhibit flowering.

Staking

• Sunflowers that grow over 3 feet tall or have large, heavy flower heads are vulnerable to flopping or even breaking under the stress of summer winds and rain. Loosely attach your plant’s branches to stakes with cloth or twine to prevent this problem. Sunflowers grown from seed sown directly in the garden will have well-established roots and stronger stems and be less likely to fall.
• To further encourage proper root growth, provide well-draining, organically-rich soil, and plenty of space between plants. And don’t forget to water deeply so that the roots will grow down rather than out.