Even though sunflowers have been cultivated for hundreds of years, professional growers are still discovering new methods for increasing output and improving the overall quality of the crop. Plus, as new uses for the byproducts of sunflowers (seeds, oil, etc.) are developed, the crop acreage has increased. Today, nearly 3 million acres are cultivated annually in the U.S. alone.

Below, I'll describe how to plant sunflowers to ensure your crop, large or small, maintains its quality. I'll also provide a few tips for fertilizing and protecting your crop while it grows.

Planting Your Sunflowers

Sunflower crops can usually be planted as early as April, though many farmers wait for May when the weather is warmer. The higher temperatures allows for quicker drying and an earlier harvest. When you're planting sunflowers, keep in mind that the crop output (in seeds) is often inversely correlated to seed rate (or, plants per acre). In other words, sunflower heads tend to produce larger quantities of seeds when the crop is thin. As a rule of thumb, plan to have approximately 20,000 seeds per acre. Also, the wider the rows, the more easily you can manage the weeds.

The sunflowers should be planted approximately 1 1/2 inches deep once the soil is warm enough (at least 50 degrees Fahrenheit). In some locations, this can require waiting until May, when higher temperatures are prevalent. One quick note: sunflowers are more vulnerable to birds later in the season. The earlier they're planted, the earlier they can be harvested, limiting the damage potential.

Fertilizing Your Crop

Sunflowers are normally resilient crops as long as they have a source of necessary nutrients. These include potassium, phosphorus, and nitrogen. If these nutrients are not plentiful in the soil, you'll need to use a fertilizer to supply them. Your crops will respond best to the fertilizers when the soil is lacking in sufficient nutrients and the weeds are actively managed.

Most fertilizers will have a series of ratings on the packaging (for example, 20-20-10). These ratings are referred to as the "analysis" of the fertilizer. They represent the percentages of nitrogen, phosphorus and potassium that are found within it. A solution with a 10-15-10 analysis should be sufficient for small crops planted in late April or early May.

Protecting Your Sunflowers

There are a number of things that can impact your crop and cause damage, including weeds, insects, and disease. Weeds are an issue and should be controlled, but the size and aggressiveness of sunflowers make weeds less of a problem than insects and disease. In many locations, the crop may attract large numbers of cutworms and grasshoppers in its earliest stages of growth. But, the real problem occurs when the sunflowers' heads begin to grow. Insects often attack the portion of the stem located directly below the heads. Fortunately, you can use one of several types of effective insecticides to protect the stems and heads.

There are a few dozen diseases that can impact your sunflowers, though your crops are most susceptible to fungi (during the early stages), sclerotinia, and bacteria. One of the best ways to prevent the spread of disease through your sunflowers is to follow proper rotation methods and limit cultivating the crops in the same soil to once every 3 years.

It's likely that sunflower acreage will continue to increase as the world pursues further development of the crop as a multi-use natural resource. To maintain optimum crop output while preventing damage from insects and disease, follow the advice provided above. Over time, planting, fertilizing, and protection methods will probably change. As they do, professional sunflower growers will need to adapt.