Overview
Helianthus borealis E.E. Wats., commonly known as the northern sunflower, is a perennial plant belonging to the Asteraceae family. Its native range spans across North America from Alaska to Labrador and down to the northern United States.General Appearance
The plant grows up to 100 cm tall, with a single stem that branches at the top to produce numerous flower heads. The leaves are lanceolate and toothed, with a rough texture, reaching up to 15 cm in length. The flower heads are 5-10 cm in diameter, with yellow petals surrounding a central disk of dark brownish-purple florets. The flower heads bloom in late summer and early fall.Common Names
In addition to its common name, northern sunflower, it is also sometimes referred to as thin-leaved sunflower, pale sunflower, or boreal sunflower.Uses
Native North American people used different parts of Helianthus borealis for medicinal purposes. The roots were crushed to make a poultice for treating sores and swellings, while a tea made from the roots was used to treat coughs and colds. The leaves were steeped as a tea to treat kidney disorders. Today, Helianthus borealis is cultivated as an ornamental plant in gardens and landscaping, appreciated for its bright yellow flowers, and drought-tolerant nature. The plant also provides food for bees and butterflies.Light requirements
Helianthus borealis E.E. Wats., commonly known as Northern Sunflower requires full to partial sun for optimal growth. As a part of the Sunflower family, Helianthus borealis requires sunlight for photosynthesis, flowering, and seed production. Insufficient sunlight affects the blooming of flowers and seed production. However, in extremely hot and dry climates, partial shade can be advantageous to regulate the temperature and conserve moisture levels.
Temperature requirements
Helianthus borealis E.E. Wats. can tolerate a wide range of temperatures. The plant can grow in USDA hardiness zones 2-10. However, it grows best in temperate climates where temperatures range from 15°C to 27°C. Helianthus borealis can withstand freezing temperatures and snow during the winter months but may lose its leaves. Extreme heat, on the other hand, can affect the quality of flowers and seed production while stunting the growth of the plant.
Soil requirements
Helianthus borealis E.E. Wats. can grow in a wide range of soil conditions as long as the soil is well-draining. The plant prefers fertile, moist, and well-draining soil but can adapt to sandy or clay soils. Soil pH levels between 6.0 to 7.5 is ideal for optimal growth. However, Helianthus borealis can grow in slightly acidic to slightly alkaline soils as well. The use of organic manure or compost can provide essential nutrients to the plant and improve the quality of the soil.
Cultivation methods for Helianthus borealis E.E. Wats.
Helianthus borealis E.E. Wats. thrives in areas with full sun, well-draining soil and requires a lot of moisture and nutrients. The plant can be grown from seeds or transplanted seedlings. The best time to sow seeds is in the spring when the soil is warm, but the plant can be started indoors a few weeks before transplanting.
It is essential to choose a planting location that receives at least six hours of sunlight daily. The soil should be prepared by mixing in organic matter like compost or decomposed manure. Once the plant is established, it requires minimal weeding and can tolerate dry conditions for a short period.
Watering needs
Helianthus borealis E.E. Wats. requires frequent watering, especially during the growing season, to ensure that the soil stays consistently moist. The water should be applied directly to the base of the plant to avoid getting the leaves wet, which can lead to leaf spot or other fungal diseases. Watering should be reduced significantly in the fall when the plant starts to prepare for dormancy.
Fertilization
Helianthus borealis E.E. Wats. is a heavy feeder and requires frequent fertilization to thrive. A slow-release, balanced fertilizer with equal amounts of nitrogen, phosphorus, and potassium can be applied every two to three months. Alternatively, organic fertilizers like bone meal, blood meal, or fish emulsion can be applied once a month. Avoid over-fertilizing the plant, which can lead to stunted growth and increased susceptibility to diseases and pests.
Pruning
Helianthus borealis E.E. Wats. does not require much pruning but can benefit from some maintenance pruning. Dead or damaged leaves and stems should be removed promptly to prevent the spread of diseases and pests. The plant can also be pruned to control its size and shape. Pinching the tips of the stems can encourage branching and result in bushier growth. However, it is best to avoid pruning the plant during the fall when it prepares for dormancy.
Propagation of Helianthus borealis E.E. Wats
Helianthus borealis E.E. Wats can be propagated either through seeds or vegetative propagation methods such as division, layering, or stem cuttings.
Seed Propagation
The easiest and most common method of propagating Helianthus borealis is through seeds. The seeds are readily available and can be sown directly into the soil in the spring or fall. The soil should be well-draining and moist. The seeds should be planted about 1 inch deep and 6 inches apart. They will germinate in 7-14 days and will grow to full maturity within 3-4 months.
Division Propagation
Division is another propagation method that can be used for Helianthus borealis. This method involves dividing the plant into two or more sections by separating its roots. It is best done in the spring or fall when the plant is dormant. Cut the plant at its base, then gently pull the sections apart. Re-plant them in well-draining soil and water them well. Make sure they are kept moist until they start to grow again.
Layering Propagation
Layering is a propagation method where a branch or stem of the plant is bent down and covered with a layer of soil while it is still attached to the parent plant. The branch will eventually grow roots and can be cut off and replanted as an independent plant. This method is best done in the spring when the plant is actively growing.
Stem Cuttings Propagation
Stem cuttings can also be used to propagate Helianthus borealis. The cuttings should be taken from the growing tips of the plant. Dip the cut end of the stem into rooting hormone and plant it into soil or a mixture of peat moss and sand. Keep the soil moist and warm until the roots begin to grow, which can take several weeks.
Disease and Pest Management for Helianthus borealis E.E. Wats.
Helianthus borealis E.E. Wats., or northern sunflower, is a tough and hardy plant that grows well in various environmental conditions. However, like any other plant, it is not entirely immune to diseases and pests.
Common Diseases
One of the common diseases that affect Helianthus borealis is stem rot, which is caused by the fungi Sclerotinia sclerotiorum. The disease causes wilting, yellowing of leaves, and the collapse of stems. Another disease that affects the plant is rust caused by Puccinia helianthi. Rust results in yellowing of the leaves and the formation of reddish-brown spots on the leaves' undersides.
Pest Management
One of the common pests that affect Helianthus borealis plants is aphids. These insects suck sap from the plant, causing curling of leaves, stunted growth, and deformation of flowers. Another common pest is the sunflower moth. The caterpillar of this moth feeds on the developing bud of the plant, causing bud abortion and flower head damage.
Management Strategies
To manage stem rot disease, remove and destroy infected plant debris and avoid overhead watering. For rust management, planting tolerant cultivars and practicing crop rotation are effective management strategies.
Control of aphids can be achieved by introducing natural predators such as lacewings and ladybugs. Alternatively, insecticidal sprays can help in reducing the aphid population. For the control of the sunflower moth, handpicking the caterpillars and infected flower heads can significantly reduce the pest's population.
Proper cultural practices, including fertilization, irrigation, and weed control, can significantly reduce the incidence and severity of diseases and pests in Helianthus borealis. Additionally, early detection and immediate treatment of any infestation can help prevent the spread of diseases and pests to other plants in the garden or field.
Finally, it is essential to select disease-free and healthy plant material when planting Helianthus borealis. This proactive measure can significantly reduce the chances of infections and infestations in the garden or field.
