Sunflowers are among the easiest flowers to grow, and they thrive in the heat of our summers here. This quick easy growth is why children are often so delighted with sunflowers. Depending on the cultivar, sunflowers will bloom anytime from about 55 to 75 days after planting the seeds (check the seed package information). Sunflowers can be broadly divided into those that are grown for production of edible seeds and those grown as ornamentals and for cut flowers.
You can start sunflower seeds in small containers with drainage holes and filled with potting soil. Locate the containers in full sun to produce strong, stocky transplants. Make sure you water regularly and never allow the soil to become dry. When the seedlings have grown 4 to 6 inches high, transplant them to sunny flower beds.
You can also sow the seeds directly into a prepared garden bed in full sun. After sowing the seeds, water the bed well, and then water the bed as needed to keep the soil moist (water lightly every day if the weather is dry).
While children often get a big thrill out of growing giant sunflowers, adults may find them a bit overwhelming for their gardens. Thankfully, breeders have developed a wild range of sunflower heights, and you can find cultivars that grow anywhere from about 1 foot to 8 feet tall or more.
In addition to a wide range of heights, sunflowers also come in a wide range of colors. While brilliant yellow will always be popular, you can also choose from creamy white, bronze, mahogany, rusty red, burgundy and orange, with some types producing flowers with more than one color. The center disk of the sunflower also adds to the display and goes through color changes as the flower matures and seeds form. There are even fully double types that produce flowers full of petals with no central disk at all (such as Teddy Bear).
Sunflowers that are grown for cut flowers generally produce numerous flowers on a more bushy plant than those types grown for seeds, which generally produce a single large head. The multiple-flowering habit makes these types more colorful and fits into traditional flower beds more appropriately. They come in a wide variety of colors.
If you want to grow sunflowers for the delicious, nutritious seeds, make sure you choose cultivars bred for seed production, such as Mammoth Russian (also known as Mammoth, Russian Giant and Gray Stripe). These tall-growing sunflowers produce a single, enormous flower at the top of the plant. To grow a really big seed head, make an application of general-purpose fertilizer when the flower head begins to appear.
The versatility and variety of today’s sunflowers offer something for almost every garden and gardener. If you haven’t tried this native American plant lately, give it another look.
The LSU AgCenter and the LSU College of Agriculture