How to Grow Autumn Sun
Wikimedia Commons
Autumn Sun
Helianthus annuus 'Autumn Sun'
flowerAutumn Sun is a stunning sunflower cultivar prized for its rich golden-bronze and deep red coloring that intensifies as the flower matures. This tall variety produces large, double-petaled blooms that resemble dahlias and reaches heights of 5-7 feet, making it an excellent choice for garden drama and cut flower arrangements. The flowers attract pollinators and provide seeds for wildlife in fall.
When should you plant Autumn Sun in your zone?
Get a personalized planting timeline — when to start seeds, transplant, and harvest — based on your USDA zone and local frost dates. Free to start.
Example Autumn Sun timeline · Pittsburgh, PA (Zone 6b)
-
Plant Autumn Sun
Around Apr 17Near Pittsburgh's average last spring frost.
-
Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
-
First Autumn Sun blooms
Around Jun 26≈ 70 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Autumn Sun dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 2-9; prefers cooler to moderate climates
Sign up free to see if Autumn Sun grows in your zone — and get a personalized planting timeline.
Get my Autumn Sun timeline →Growth Stages
Seedling
2-3 weeksSmall green leaves emerge with cotyledons visible; plant is fragile and low-growing.
Keep soil consistently moist. Protect from strong winds. Thin seedlings to proper spacing when 3-4 inches tall.
Vegetative
4-6 weeksRapid stem elongation with multiple true leaves developing; plant becomes sturdy and establishes deep root system.
Support tall growth with staking or caging. Water deeply but less frequently. Pinch tops early if bushier growth is desired (reduces height slightly).
Budding
2-3 weeksFlower bud forms at stem apex; bud swells gradually and shows early color hints of golden tones.
Maintain consistent watering. Apply balanced fertilizer. Monitor for pest activity. Ensure stakes are secure as plant weight increases.
Flowering
3-4 weeksLarge double-petaled blooms open, displaying golden-bronze petals with deep red-burgundy coloring that deepens over several days.
Water at soil level to keep petals dry. Deadhead spent flowers to encourage side blooms if desired. Support heavy flower heads.
Seed Development & Harvest
3-4 weeksPetals fade and drop; seed head develops plump seeds in geometric spiral pattern; heads dry and turn brown.
Allow flowers to dry on plant for seed harvest. Cut for arrangements before petals drop completely. Leave standing for wildlife feeding.
Common Pests
-
Hand-pick affected buds. Use spinosad spray. Monitor for entry holes in stems.
-
Hand-pick beetles and larvae from young plants. Use neem oil or insecticidal soap.
-
Spray foliage with water to dislodge. Use miticide or neem oil if severe. Ensure adequate humidity.
-
Spray with insecticidal soap or water spray. Encourage beneficial insects like ladybugs.
Uses
Edible Seeds
CulinaryMature seeds can be roasted and eaten as nutritious snacks, or pressed for oil high in linoleic acid and vitamin E. [source]
Cut Flowers & Arrangements
CraftThe dramatic double-petaled blooms with rich autumn coloring are prized for floral arrangements and bouquets, lasting 1-2 weeks in water with excellent vase life. [source]
Pollinator & Bird Food
WildlifeFlowers attract bees, butterflies, and pollinators; seed heads provide food for finches, sparrows, and other wildlife through fall and winter. [source]
Natural Dye Source
HouseholdPetals and leaves can be used to create golden and brown natural dyes for textiles and crafts. [source]
Phytoremediation & Wellness
MedicinalSunflowers are known for phytoremediation capabilities; seeds and oil contain compounds supporting heart health and antioxidant wellness. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Cut stems for arrangements when outer petals are just beginning to open, using clean sharp scissors or knife early in the morning. For seed harvest, allow flowers to mature fully on plant, then cut entire head when disk florets turn brown. Hang heads upside down in dry location to finish drying (2-4 weeks), then thresh seeds from head.
Fun Facts
- 🌱 Autumn Sun's color intensity increases as temperatures cool in fall, with the deep burgundy tones becoming more pronounced—making it a true 'autumn' sunflower despite being planted in spring.
- 🌱 Sunflowers are heliotropic (sun-tracking) when young, rotating their flower buds to follow the sun throughout the day, but mature Autumn Sun flowers typically face east and remain stationary to warm-seeking pollinators.
- 🌱 The large seed heads can weigh several pounds when mature, and a single Autumn Sun plant can produce hundreds of viable seeds that remain viable for 4-6 years.
Gardening Terms
New to gardening? Learn about terms used in this guide:
Join 30,000 gardeners planning their gardens with LizPlants.
Get your personalized Autumn Sun planting timeline
Tell us your zip code and we'll calculate exactly when to start Autumn Sun seeds, transplant seedlings, and harvest — based on your USDA zone and local frost dates. Includes calendar reminders and printable task lists. Free to start.
Get my Autumn Sun timeline →