The Story
Plant Bio
Platycodon grandiflorus 'Astra Double Blue' is a compact perennial with bushy growth and ovate green leaves, producing abundant, large double blue flowers with a bell-shaped form during summer.
This cultivar is distinguished by its densely double flowers, creating a lush, pom-pom appearance that adds a striking ornamental element to borders and containers.
Uses & Benefits:
Essentials
At a Glance
Plant Type
Perennial
Height
12 inches
Width
12 inches
Light
Full Sun, Partial Sun
Zones
4, 5, 6, 7, 8
Water
Moderate
Humidity
Average
Lifespan
Perennial
Native To
East Asia
Toxicity
Non-toxic to humans and pets
Bloom period
Summer – Early summer
In flower about 12 months of the year
Planting
How to Grow
- Tuck seeds into moist soil in early spring.
- Keep soil consistently moist during germination, about 2 weeks.
- Transplant seedlings when they are 3 inches tall, after last frost.
- Plant in well-drained loamy soil with full sun exposure.
- Water regularly during dry spells for best flowering.
- Mulch around plants to retain moisture and suppress weeds.
Pro Tip
Ensure well-drained soil and full sun for abundant blooms.
Keep It Thriving
Care Guide
Do
- Water regularly to keep soil moist 🌱
- Deadhead spent flowers to encourage reblooming
- Apply a balanced fertilizer in spring
Don't
- Avoid waterlogging, which can cause root rot ❌
- Don’t disturb roots during flowering
- Refrain from over-fertilizing, which can reduce bloom quality
Seasonal Care Calendar
| Task | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Deadhead | ||||||||||||
| Divide | ||||||||||||
| Spring Cleanup |
Watch Out For
Pests & Diseases
Common Pests
Common Diseases
In the Garden
Landscape Uses & Companions
Landscape Uses
Multiply
Propagation Methods
Good to Know
Common Questions
Astra Double Blue Balloon Flower questions
What zones can Astra Double Blue Balloon Flower grow in?
Astra Double Blue Balloon Flower is hardy in USDA Zones 4–8. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.
Is Astra Double Blue Balloon Flower deer resistant?
Yes — Astra Double Blue Balloon Flower is rated deer-resistant. Deer typically pass it over, though extreme hunger can override any plant's defenses.
When does Astra Double Blue Balloon Flower bloom?
Astra Double Blue Balloon Flower typically blooms in summer through early summer. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.
Does Astra Double Blue Balloon Flower need full sun?
Astra Double Blue Balloon Flower does best in full sun to part shade. In hot climates, afternoon shade keeps blooms fresher longer.
More Platycodon to compare
Balloon Flower
Platycodon grandiflorus 'Mix'
Balloon Flower 'Sentimental Blue'
Platycodon grandiflorus 'Sentimental Blue'
Astra Pink Balloon Flower
Platycodon grandiflorus 'Astra Pink'
Fairy Snow Balloon Flower
Platycodon grandiflorus 'Fairy Snow'
Balloon Flower Shell Pink
Platycodon grandiflorus 'Shell Pink'
Fuji Blue Balloon Flower
Platycodon grandiflorus 'Fuji Blue'
Keep exploring
Explore the genus
Hardy in your zone?
Grow Astra Double Blue Balloon Flower with confidence
See it in a design of your actual yard, get zone-matched care reminders, and track it season by season in your garden journal.