The Sunflower (Helianthus annuus) is a spectacular plant, whether for its giant beauty or its ability to produce numerous seeds of high nutritional value. As the name suggests, the inflorescences of the sunflower perform heliotropism, meaning they follow the sun. Being a species that was domesticated thousands of years ago, humans have developed a large number of varieties for two main purposes: Non-branching plants with large single heads and numerous seeds for food use and oil production; and highly branching plants with more than one floral head for ornamental use.
Most sunflowers are tall, reaching 13 feet (4 meters) in cultivation, with a herbaceous and hairy stem. Their leaves are oval to heart-shaped, also very hairy, giving them a grayish color. The inflorescences, known as heads, are very large, reaching 12 inches (30 cm) in diameter. They contain two types of flowers, the peripheral ligulate and the central, fertile, and hermaphroditic ones. However, sunflowers rarely self-pollinate, requiring manual or insect pollination with pollen from other individuals. The fruits formed are achenes.
Sunflowers are very useful in landscaping; the giant and branching varieties can be planted in rows along fences and walls to temporarily hide them. Care should be taken when using the giants, as in small spaces they can become disproportionate, “reducing” the constructions. The dwarf varieties are suitable for forming massifs, borders, and flowerbeds and are also widely sold in pots and planters. They can have single and double flowers in various colors, but mainly yellow, red, orange, and brown. They are especially recommended for children to cultivate due to their rapid development and life cycle, making them very educational.
We must not forget to highlight the importance of the sunflower in the diet of people and animals, due to its seeds and forage of high protein and caloric value, in addition to being rich in vitamin E. Currently, biodiesel can also be produced from its oil, making it an excellent source of renewable energy.
They should be cultivated in full sun, in fertile soil enriched with organic matter. Some varieties can tolerate partial shade, but the stem that develops fragile is at risk of toppling with the weight of the plant. It appreciates regular watering but can tolerate a short dry period. It multiplies easily by seeds sown in spring and summer.
