Fertilizing Sunflowers

Fertilizing helps plants thrive by providing nutrients that support healthy roots, stems, and flowers. Plants in nature are sustained as nearby plant matter breaks down and naturally fertilizes the ground. Landscape and potted plants do not have that benefit, so they need you to address the nutrient deficiency. You should fertilize sunflowers to keep the plants healthy and blooming. These plants are heavy feeders, and newly planted sunflowers acclimate more quickly and have a fast growth rate when they are fertilized. It’s a good idea to fertilize annual and perennial sunflowers to help the plants reach their full potential.


How to Fertilize Sunflower

Water plants after applying granular fertilizer. Water helps the granules dissolve. Wet roots are better able to absorb nutrients and are less likely to experience fertilizer burn. Water-soluble fertilizers can be mixed into water and applied during routine watering. Apply fertilizer to the ground several inches away from the base of the plant. You want to avoid fertilizer coming into contact with the foliage and stems as much as possible. Sunflower roots are deeper than wide, so apply fertilizer above the root ball so the roots can absorb it as it sinks into the soil.

Before fertilizing, test the soil, including its pH, and select a fertilizer to support the plant better. Sunflowers prefer soil that has a 6.0-7.5 pH. 

Best Time To Fertilize Sunflower

Fertilize perennial sunflowers in the spring or early summer when new growth appears. Perennial sunflowers need to be fertilized once each year. These plants have an established root system to sustain them, but an annual fertilizer application will help them return strong each year.

Annual sunflowers in high-quality soil will grow very well and may not need to be fertilized. However, fertilizing annual sunflowers will ensure a bumper crop of flowers. Fertilize annual sunflowers planted in low-quality soil or if the plants are lagging.


Best Fertilizer For Sunflower

Feed sunflowers using a balanced formula with a ratio of 10-10-10 or a product low in nitrogen with a 5-10-10 NPK ratio. A balanced fertilizer will support the entire plant. Nitrogen supports heavy foliage growth, and nitrogen-rich fertilizers are a good choice for leafy plants. Sunflowers are grown for their flowers, so even amounts of nitrogen are acceptable and low nitrogen will encourage more blooms.

Slow-release fertilizers are good for perennial and annual sunflowers because they provide continued support over the growing season. Using a slow-release fertilizer is also easy since one application will last the entire year. Perennial sunflowers are heavy feeders, and a slow-release fertilizer coupled with rich soil or a topdressing of organic compost will help the plant thrive. 

Sunflower Fertilizing Tips

  • Apply fertilizer to perennial fertilizers when new growth appears
  • Fertilize annual sunflowers when planting or if growth is slowed
  • Use a slow-release fertilizer for sunflower plants
  • Fertilizer should have a balanced NPK ratio or low nitrogen content


-Always wear protective gloves and a face mask when handling chemical fertilizers.

-Closely follow all directions and storage guidelines that are on the fertilizer label.

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Author Alison Cotsonas - Published 05-01-2023