Overview
Helianthus annuus L. ssp. lenticularis (Dougl. ex Lindl.) Cockerell, commonly known as the Flattop Sunflower, is a subspecies of the well-known sunflower, Helianthus annuus. This sunflower is native to western North America, where it can be found from California in the south to British Columbia in the north.
General Appearance
The Flattop Sunflower typically grows between 60 to 200 cm tall and has a solitary stem with few or no branches. The stem is erect, hairy, and rough to the touch. The leaves are large, rough, and green, with pointed tips and serrated edges. The flowers of the Flattop Sunflower are yellow and have a distinctive flattened shape. The flower heads can range in size from 8 to 15 cm wide and have a central disk that is surrounded by 10 to 20 bright yellow petals.
Common Names
The Flattop Sunflower is commonly known by several names, including the Wild Sunflower, Diablo Sunflower, and Colorado Sunflower.
Uses
The Native American tribes of the western United States used the Flattop Sunflower for various medicinal purposes, including treating respiratory issues, infections, and fever. The seeds of the sunflower were also an important source of food and were roasted, ground, and used to make cakes and bread. Today, the sunflower is cultivated for its oil-rich seeds and is commonly used in cooking and for making various food products. Additionally, the flower is also grown as an ornamental plant in gardens and landscaping.
Light requirements
The plant Helianthus annuus L. ssp. lenticularis (Dougl. ex Lindl.) Cockerell requires full sun exposure to thrive. It needs at least 6 hours of direct sunlight daily to grow properly. The plant will not grow or bloom in shady areas.
Temperature requirements
The ideal temperature range for Helianthus annuus L. ssp. lenticularis (Dougl. ex Lindl.) Cockerell is between 20°C to 30°C. The plant can tolerate temperature fluctuations but is sensitive to frost and high temperatures. Extreme heat can cause the plant to wilt and die.
Soil requirements
The plant prefers well-drained soil that is rich in nutrients. Helianthus annuus L. ssp. lenticularis (Dougl. ex Lindl.) Cockerell can grow in various soil types, including sandy and clay soils. However, the soil should be slightly acidic to neutral (pH 6.0-7.5) for optimal growth.
Additionally, the plant requires regular watering, especially during its growing season. But, the soil must not be waterlogged as it may cause root rot. A good practice is to water the plant when the topsoil is dry to touch.
Cultivation Methods
The Helianthus annuus L. ssp. lenticularis, commonly known as the wild sunflower, requires full sunlight to grow correctly. Therefore, it is best to plant them in areas that receive at least six hours of bright sun every day. This plant prefers well-draining soil with a pH range of 6.0 to 7.5. You can prepare the soil by adding organic matter like compost or aged manure at least two weeks before planting. It is also important to avoid planting sunflowers in areas that have previously grown sunflowers or any other plants from the same family (Asteraceae) since they may introduce pests and diseases to the soil.
Watering Needs
During the first few weeks after planting, ensure that the soil is consistently moist, but not water-logged. Once established, sunflowers require moderate watering, and you only need to water them when the topsoil feels dry to the touch. Overwatering may lead to root rot, so it is essential to avoid wetting the foliage when watering. A drip irrigation system is ideal for watering sunflowers since it delivers water directly to the root zone while minimizing water waste and foliar diseases.
Fertilization
Sunflowers grow fast and require nutrient-rich soil to thrive. If the soil is not fertile enough, you may add a balanced all-purpose fertilizer before planting or during the growing season. Sunflowers do best with fertilizers that have a high nitrogen content (N) during the vegetative stage and phosphorus (P) and potassium (K) during flowering. However, too much nitrogen may result in tall, spindly sunflowers with smaller blooms. It is advisable to follow the fertilizer manufacturer's instructions to avoid over-fertilizing, which may burn the roots.
Pruning
Wild sunflowers need minimal pruning, and most often, you will not have to prune them at all. However, if you notice that the plant is growing too tall and leaning, you may pinch the stem's top. This technique halts vertical growth, encourages lateral branching and helps create a bushier plant. Additionally, you may remove spent flower heads once they have wilted to encourage the plant to divert more energy into seed production. This process helps prolong the flowering season and prevents self-seeding, which can lead to overcrowding or unwanted hybrids.
Propagation of Helianthus annuus L. ssp. lenticularis (Dougl. ex Lindl.) Cockerell
Helianthus annuus L. ssp. lenticularis (Dougl. ex Lindl.) Cockerell, commonly known as the prairie sunflower, is a native plant to the western United States. It is a perennial plant with a short lifespan and can be propagated through various methods.
Seed Propagation
One of the most common methods of propagating Helianthus annuus L. ssp. lenticularis is through seeds. It is best to start the seeds indoors in early spring or sow them directly in the garden after the danger of frost has passed. Seeds are sown at a depth of 1/4 to 1/2 inch deep in well-draining soil. Keep the soil moist, and germination should occur in 7-14 days.
Division
Another method of propagating Helianthus annuus L. ssp. lenticularis is through division. Divide the plant in early spring before new growth occurs or in the fall when the plant has finished flowering. Dig up the plant and carefully divide it into smaller sections, making sure that each section has roots and shoots. Replant the divisions in well-draining soil and keep them moist until they become established.
Vegetative Propagation
Helianthus annuus L. ssp. lenticularis can also be propagated vegetatively through stem cuttings. Take stem cuttings in the summer when the plant is actively growing. Cut a 4-6 inch long stem from the plant, remove the lower leaves, and dip the cut end in rooting hormone. Place the cutting in a pot filled with moist soil and keep it in a warm, bright location until new growth appears. After new growth appears, the cutting can be transplanted to its permanent location in the garden.
Disease and Pest Management for Helianthus annuus L. ssp. lenticularis
Helianthus annuus L. ssp. lenticularis is a sunflower variety that is commonly grown for its edible seeds having high oil content. Managing disease and pest infestations is crucial for quality seed production. Here are some common diseases and pests that may affect Helianthus annuus L. ssp. lenticularis and methods to manage them:
Diseases
1. Downy mildew - This fungal disease causes yellowing of leaves and the appearance of fuzzy white mold underneath them. To manage downy mildew, avoid overhead watering, provide good air circulation, and treat with copper-based fungicides.
2. Rust - Rust appears as orange, yellow, or brown pustules on leaves. To prevent rust, avoid watering plants in the evening, remove infected leaves, and treat with fungicides that contain chlorothalonil or copper.
3. Verticillium wilt - This fungal disease causes leaves to yellow and wilt. Eventually, the entire plant will collapse. There is no treatment for verticillium wilt, so practice crop rotation and avoid planting the same species in the same area for at least four years.
Pests
1. Aphids - Aphids are small, soft-bodied insects that suck plant fluids, resulting in yellowing, stunted growth, and distorted leaves. To manage aphids, blast the plants with a strong jet of water to dislodge them, and use insecticidal soap or neem oil.
2. Sunflower moth - The sunflower moth lays its eggs in the flowers, and the larvae consume the seeds. To manage sunflower moth, prevent the larvae from entering by using row covers, and monitor plants for infestations.
3. Stem weevils - Stem weevils feed on the stems, causing wilting and death of the plant. To manage stem weevils, remove affected plants, use sticky traps, and apply insecticides that contain carbaryl or permethrin.
In conclusion, proper disease and pest management is essential for good seed production in Helianthus annuus L. ssp. lenticularis. Timely monitoring, identifying, and treating of common diseases and pests will lead to healthy and productive plants with good yields.
