What Fertilizers Do Sunflowers Like the Best?

Slow-Release, Granular Fertilizer

• Sunflower crops produce optimally with a slow-release, granular fertilizer applied at regular intervals. The slow-release component ensures that the young plants will mature properly without getting too much fertilization at one time. Slow-release, granular fertilizers come in containers that allow you to shake the product quickly over the planting area with no mixing.

Nitrogen

• Sunflowers do not require large amounts of nitrogen like some other plants. Too much nitrogen on your sunflower plants will decrease oil content and can significantly delay blooming. Using a basic liquid fertilizer such as a 10-16-10 fertilizer will provide plenty of nutrients for a thriving crop. Numbers such as 10-16-10 represent a fertilizer's content of nitrogen, phosphorus and potassium, respectively.

Organic Matter

• Organic matter such as leaves, grass and mulch placed around your sunflowers will provide nutrients organically and also help to hold water in the soil, allowing for less frequent watering. If you use organic matter, additional fertilizing may not be necessary because the rich nutrients from the organic matter supplements the soil's needs. Sunflowers have large flower heads, and so the plants need the support of deep, spreading roots. Regular watering encourages healthy root growth, which gives the plants the support they need to hold the weight of their flower heads.