Stella Sunflower (Helianthus annuus ‘Stella’) is a popular annual known for its distinctive appearance and extended blooming period. Its branching habit and multiple blooms provide continuous cheer in garden beds and a steady supply of cut flowers.
Understanding Stella Sunflowers
Stella Sunflowers differ from typical single-stem varieties due to their branching structure. Instead of one large flower, ‘Stella’ produces multiple blooms on side branches, resulting in a prolonged display. These plants generally reach a height of 100 to 180 cm (3 to 6 feet). The flowers typically feature golden yellow, spider-like petals with a dark brown or black center disk, creating a striking visual contrast.
The branching nature allows for a longer flowering season, often extending from July through October. Each stem can produce between two and six flowers, ensuring a continuous succession of blooms. The petals are thin and sometimes described as twisted, resembling a cactus dahlia. Stella Sunflowers are also pollenless, which prevents pollen mess when used as cut flowers.
Planting Stella Sunflowers
Planting Stella Sunflowers requires selecting an appropriate site and timing. These plants thrive in full sun, needing at least six hours of direct sunlight daily for abundant flowering and vibrant color. Planting should occur after the last frost, when soil temperatures consistently remain above 60°F (15.5°C). Seeds can be direct-sown into the garden or started indoors a few weeks before the last frost.
For direct sowing, plant seeds approximately 1.5 cm (0.5 inches) deep. Space plants 30-60 cm (12-24 inches) apart to accommodate their branching growth. If starting indoors, use biodegradable pots to minimize root disturbance during transplanting, as sunflowers generally do not respond well to root disruption. Enriching the soil with compost or well-rotted manure before planting provides a beneficial start.
Caring for Stella Sunflowers
Ongoing care helps Stella Sunflowers flourish throughout their growing season. Regular, deep watering is important, especially during dry periods, to ensure healthy growth. Sunflowers perform best with consistent watering before, during, and after their flowering phase. Once established, they can tolerate some drought, but adequate moisture supports their development.
Sunflowers are heavy feeders. While they can grow well in quality soil without additional feeding, fertilizing can promote a greater abundance of flowers. A balanced fertilizer, such as a 10-10-10 NPK ratio, or one low in nitrogen (e.g., 5-10-10) is suitable, as excessive nitrogen can lead to vigorous foliage growth at the expense of flower development. Apply fertilizer several inches away from the plant’s base, avoiding contact with foliage.
Deadheading spent blooms encourages the plant to produce more flowers and extends the overall blooming period. To deadhead, locate a healthy leaf below the withered bloom and cut the stem about half an inch above it.
Harvesting and Uses
Stella Sunflowers are valued as cut flowers due to their multi-stemmed nature and extended bloom period. To maximize vase life, harvest blooms early in the morning when the outer petals are just beginning to unfurl, but before the central disk flowers fully open. Use sharp pruners to make a clean cut at a 45-degree angle, just above a leaf node; this can encourage the plant to produce more stems. Immediately place harvested stems into a bucket of water, ideally with a floral preservative, to maintain hydration. Remove any leaves that would fall below the water line in the vase to prevent bacterial growth.
Stella Sunflowers also contribute to garden ecology. They attract pollinators such as bees and other beneficial insects, supporting biodiversity. The seeds can be harvested in autumn for bird feed, providing a natural food source for wildlife. The plants add aesthetic value to garden beds and naturalistic landscapes, serving as a bright, cheerful feature.