Cherished for their beauty, Sunflowers (Helianthus) are striking ornamental annuals or perennial plants grown for their colorful summer and fall blooms. Fast-growing, they can reward you with glamorous blooms between 55 and 100 days after planting, depending on the variety grown. They are exceptionally care-free plants if they are given a well-chosen site. Here are some basic rules that need to be followed to enjoy their splendid flowers.
1. Select The Right Site
- Sunflowers prefer full sun - at least 6 hours of direct sunlight per day.
- Sunflowers enjoy average, moist, well-drained soils. They are not fussy about soil conditions as long as they are not waterlogged.
- Sunflowers are heavy feeders so the soil needs to be fairly rich with lots of organic matter or composted manure.
- A sheltered location is preferred, as the wind may catch their heavy heads.
2. Planting Your Sunflowers
- Annual Sunflowers seeds can be planted directly into the soil after the threat of frost has passed, when the soil has warmed up to at least 55ºF (13ºC). If you have a short growing season, you may want to start indoors.
- Perennial Sunflowers can be planted in the spring or fall - A spring planting will reward you with blooms at the end of the season.
- To prepare the bed, dig over the soil about 2 ft. deep (60 cm), then rake over and firm.
- Plant the seeds 1 in. deep (2.5 cm) and 12-18 in. apart (30-45 cm), depending on the ultimate size of the plant. Perennial Sunflowers will spread out by rhizomes. Space them at least 2-3 ft. apart, so they have space to grow.
- Carefully cover with soil and firm. Water the area gently but thoroughly with a fine spray
- A light application of fertilizer mixed in at planting time will encourage strong root growth to protect them from blowing over in the wind.
- To enjoy continuous blooms from your Annual Sunflowers, plant seeds every two weeks in succession from spring to early summer.
- While the Sunflower plant is small, water around the root zone, about 3-4 in. (7-10 cm) from the plant.
- Water deeply though infrequently to encourage deep rooting. Once established, Sunflowers can tolerate some drought.
- Keep weeds under control during the growing season.
- Add mulch to help retain soil moisture and maintain even soil temperatures.
- No fertilizer is needed unless the soil is poor. Overfertilization can cause stems to break in the fall, especially if the heads are large.
- Tall species and cultivars require support for a short period of time. Bamboo stakes will help support the stem and prevent them from breaking under the weight of the flower heads.
- Divide Perennial Sunflowers every 2-3 years.