Growers can therefore wait until most of the seeds are ripe before harvest, which is especially important when seed ripens unevenly among plants. This practice promotes production of many lateral branches that tend to flower and develop seed at the same time, which results in more uniform ripening of seeds and a shorter time from planting to maturity. Specific procedures for the drying and storage of vernonia have not been determined. Vernonia has limited possibilities as an oilseed crop for the northern continental United States. This crop flowers and sets seed too late in the growing season because shorter days are required for flower initiation and development.
Frosts follow flowering too quickly to allow complete seed development and maturation.
Trial plantings conducted at Experiment, Georgia in the 1960s produced few flowers and no seed. Trials planted in greenhouses in Glenn Dale, Maryland flowered in November and seed matured in December, which is much too late for a field crop in that area. However, a variety was found in Nigeria during the 1980s, at about 11 degrees north and south of the equator, which flowers about six weeks earlier than any plants found previously. If a variety can be found that flowers early enough in the United States to allow for maturation of the seed, does not shatter readily, and is resistant to disease and insect problems, then this oilseed crop may be suitable for the Southwest when planted in late summer or early fall. Areas that do not have a well-defined, severe dry season and soils without good drainage should be avoided.