Origin
Helianthus ×verticillatus, also known as the whorled sunflower, is a hybrid plant that originated in North America. It's believed to have been naturally crossbred from two different species of sunflowers.
Common Names
Aside from whorled sunflower, this plant is also known by other monikers, including verticillate sunflower, whorled-leaved sunflower, and bamboo-leaved sunflower.
Uses
Whorled sunflowers are grown mainly as ornamental plants for their striking appearance. They add a touch of vibrance and personality to gardens, with their tall stalks, whorled leaves, and yellow blooms that resemble daisies. These plants thrive in warm and sunny locations with well-drained soil.
In terms of wildlife, whorled sunflowers are a valuable source of food for various bird and insect species. They produce nectar that attracts bees and butterflies, which in turn, help in pollinating nearby plants.
General Appearance
Whorled sunflowers grow up to 3-8 feet tall, with thin and erect stems that can be branched or unbranched. The leaves grow in whorls around the stem, with 3-9 leaves per node. The leaves are lance-shaped, hairy, and measure up to 7 inches long and 1 inch wide.
The flowers bloom from mid to late summer, with yellow petals arranged in a characteristic sunflower pattern around a dark center disk. The disk can measure up to 2 inches in diameter, while the rays can grow up to 2-5 inches long. The seeds are produced in the fall, and they're a source of food for birds and squirrels.
Light Requirements
Helianthus ×verticillatus E.E. Wats. is a plant that prefers full sunlight. Thus, it requires at least six hours of direct sunlight every day. If it does not get enough sunlight, it may become spindly and have weak stems. Therefore, it is best to plant them in an area that has full sun exposure.
Temperature Requirements
Helianthus ×verticillatus E.E. Wats. thrives in warm temperatures. The ideal temperature range for growth is between 20°C and 30°C. It can tolerate some extreme temperatures, including hot summers and cold winters. However, it cannot withstand frost, and growth will be hindered in temperatures below 15°C. If grown in colder climates, they should be planted in early spring to maximize growth before temperatures decline.
Soil Requirements
The soil requirements for Helianthus ×verticillatus E.E. Wats. are specific. It prefers well-drained, acidic to neutral soil, with a pH range between 5.8 and 7.0. The soil should be fertile and rich in organic matter, such as compost. The plant can grow in a variety of soil types, but it does not do well in heavy clay. It is highly recommended to add compost to the planting site before planting to provide the plant with essential nutrients and improve soil structure.
Cultivation Method
The Helianthus ×verticillatus E.E. Wats. (pro sp.) plant is relatively easy to cultivate and does best in full sun, in moist and well-draining soil. It can be grown from seeds or by division. If planting from seeds, start in the spring by sowing the seeds into the ground, and keep the soil moist until they germinate. When planting by division, it is best to do it in the early spring or fall, during the dormant period, to give the roots time to establish before the summer heat. Space the plants about 2 to 3 feet apart to allow enough room for the plant to spread.
Watering Needs
The Helianthus ×verticillatus E.E. Wats. (pro sp.) plant requires regular and consistent watering, especially during the growing season, while reducing watering during the dormant winter period. The soil should be kept moist but not soggy, as too much moisture can lead to root rot. It is advisable to water the plant once a week, especially during hot weather, and twice a week during the peak of summer.
Fertilization
Fertilizing Helianthus ×verticillatus E.E. Wats. (pro sp.) can greatly enhance its growth and productivity. It is recommended to fertilize in the spring using a balanced fertilizer to encourage vegetative growth. During the summer, it is best to use a fertilizer that is high in potassium, which is essential in flower production. Apply the fertilizers directly to the soil and not on the leaves or flowers, and be sure not to over-fertilize, as it can cause the plant to burn.
Pruning
Pruning of Helianthus ×verticillatus E.E. Wats. (pro sp.) is minimal, but it is necessary to deadhead regularly to encourage more flowering and to prevent seed formation. Deadheading promotes vegetative growth and ensures a continuous bloom. You can also prune to control the size and shape of the plant. It is best to prune in the early spring before the new growth begins. Cut the dead and damaged stems at the base of the plant and the healthy branches after the first bloom.
Propagation methods for Helianthus ×verticillatus E.E. Wats. (pro sp.)
Helianthus ×verticillatus E.E. Wats. (pro sp.) can be propagated by several methods. These methods include seed propagation, division, stem cutting, and tissue culture.
Seed propagation
Helianthus ×verticillatus can be propagated by seeds, which can be collected from the plant during the fall season. The seeds should be sown in the soil in early spring. The soil should be fertile and well-drained. The ideal temperature for germination is between 15 and 21°C. The seedlings should be transplanted when they are large enough to handle. They should be planted in a sunny location with fertile soil.
Division
Helianthus ×verticillatus can be propagated by division, which involves separating the plant into smaller sections. The best time for division is in the spring or fall. The plant should be carefully dug up and the root system should be separated into several sections. Each section should have a healthy root and shoot system. The sections should be planted in a sunny location with fertile soil.
Stem cutting
Helianthus ×verticillatus can also be propagated by stem cuttings. The cuttings should be taken in the spring or summer. The cuttings should be approximately 8-10 cm long and should have several leaves. The cuttings should be planted in a soilless mixture and kept in a warm, humid area. The cuttings should be watered frequently and should root within a few weeks. Once rooted, the cuttings should be transplanted into fertile soil in a sunny location.
Tissue culture
Finally, Helianthus ×verticillatus can also be propagated by tissue culture. This method involves taking a small section of tissue from the plant and growing it in a sterile environment. The tissue is placed in a nutrient-rich medium and given the proper amount of light and other growing conditions. This method allows for the rapid propagation of identical plants. Once the plants have grown large enough, they can be transplanted into fertile soil in a sunny location.
Disease and Pest Management for Helianthus ×verticillatus E.E. Wats. (pro sp.)
Helianthus ×verticillatus E.E. Wats. (pro sp.), commonly known as Whorled Sunflower, is susceptible to various diseases and pests. Here are some common issues that might affect the plant and ways to manage them.
Common Diseases of Helianthus ×verticillatus E.E. Wats.
One of the most common diseases that affect Whorled Sunflower is fungal rust. It appears as orange, yellow, or brown pustules on the leaves, stems, and flowers. Control measures include removing and destroying infected plant parts, maintaining good air circulation, and using fungicides if necessary.
Another disease is leaf blight, which causes spots on the leaves that eventually turn brown and fall off. Proper plant hygiene, such as removing infected plant parts, can help control leaf blight. Fungicides are also effective in managing the disease.
Common Pests of Helianthus ×verticillatus E.E. Wats.
One of the most common pests that affect Whorled Sunflower is aphids. They feed on the sap from the leaves and stems and cause the plant to wilt and become stunted. Introducing predatory insects, such as ladybugs and lacewings, can help control aphids. Alternatively, a solution of water and dish soap can be sprayed on the plants to kill the aphids.
Another pest is the sunflower moth, which lays its eggs on the flowers and feeds on the developing seeds. Handpicking the affected flowers and destroying them can help control the pest. Insecticides can also be used but should be applied when the moths are most active.
