Photo: davecz2CC BY-SA 4.0via Wikimedia Commonsresized / cropped
Ontario Aster Plant Care
Symphyotrichum ontarionis (Wiegand) G.L.Nesom
Updated · Sources · How we source care data
Originating from Ontario, Canada, this plant is known for its striking purple flowers that bloom in late summer and autumn, making it a coveted addition for plant collectors seeking unique and eye-catching specimens for their gardens. The lance-shaped leaves of this plant create an elegant backdrop for the vibrant blooms, adding a touch of elegance to any landscape.
Every 7–10 days
Full sun to partial shade
50–80°F
40–70%
At a glance
How do you care for Ontario Aster?
Water Ontario Aster every 7–10 days, letting the top layer of soil dry out between waterings, and give it full sun to partial shade. It prefers temperatures of 50–80°F (10–27°C) and 40–70% humidity. Fertilize it every 6 months during the growing season.
Where Is the Ontario Aster Native To?
What Is the Ontario Aster?
Ontario Aster (Symphyotrichum ontarionis) belongs to the Asteraceae family within the Symphyotrichum genus. Ontario Aster is native to eastern North America. Ontario Aster is also known as Lake Ontario Aster, Aster ontarionis, Aster diffusus var. thyrsoideus.
Ontario Aster displays an upright, bushy perennial growth habit, reaching up to 3 ft tall with a spread of approximately 2 ft. Ontario Aster produces daisy-like flowers in various colors like purple, blue, pink, and white.
Leaf size: approximately 4 inches.
How Often Should You Water a Ontario Aster?
Symphyotrichum ontarionis requires watering every 7–10 days. Allow the top layer of soil to dry between waterings to prevent root rot. Reduce watering frequency during winter when growth slows.
Watering Frequency
Every 7–10 days
Let soil partially dry between waterings
What Light Does the Ontario Aster Need?
Ontario Aster thrives in full sun to partial shade.
Light Requirement
Full sun to partial shade
What Temperature and Humidity Does the Ontario Aster Prefer?
Symphyotrichum ontarionis grows best at temperatures of 50–80°F. Ontario Aster prefers humidity levels of 40–70%.
Temperature
50–80°F
Humidity
40–70%
What Soil Mix Works Best for a Ontario Aster?
Well-draining loamy soil with added compost for nutrients. Good drainage is essential for Ontario Aster to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Ontario Aster?
Feed Ontario Aster every 6 months during the growing season (spring and summer) with a balanced fertilizer diluted to the strength on the label.
Pause feeding in autumn and winter, when growth slows, and never fertilize dry soil — water first.
Fertilizing
Every 6 months
During the growing season
The PlantoScan app can remind you when to water and when to fertilize each plant.
How Do You Repot a Ontario Aster?
Repot every 2-3 years in early spring. Choose a pot one size larger than the current container, and ensure it has drainage holes to allow excess water to escape.
How Do You Propagate a Ontario Aster?
Ontario Aster can be propagated through division, stem cuttings. Similar propagation techniques also apply to pineywoods aster plant care, which shares the same genus.
Is the Ontario Aster Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Ontario Aster, so we can't confirm whether it is safe for cats and dogs. Keep pets from chewing it as a precaution.
This is a general caution, not veterinary or medical advice. If your pet ate a plant, contact your vet or animal poison control.
See all plants toxic to cats and plants toxic to dogs.
What Pests and Diseases Affect the Ontario Aster?
Ontario Aster is susceptible to aphids, spider mites, powdery mildew. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.
Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.
What USDA Hardiness Zone Does the Ontario Aster Need?
Ontario Aster grows outdoors in USDA Zone 12a – 8b. It survives winters down to planting zone 12a. Ontario Aster is native to eastern North America. In cooler regions, grow Ontario Aster as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 12a – 8b
Keep exploring plants
Ontario Aster is one of many species covered in the complete plant care and identification guide, which groups plants by genus, attribute, and popularity.
It belongs to the Symphyotrichum genus — compare its care with other Symphyotrichum species on PlantoScan.
Symphyotrichum is part of the Asteraceae plant family — browse all Asteraceae genera and species.
Ontario Aster thrives in bright light and direct sun — see other bright-light plants.
More Symphyotrichum Species
Other Symphyotrichum species in PlantoScan's care catalogue share similar watering, light, and soil preferences:
Sources
- Scientific name & taxonomy: Symphyotrichum ontarionis (Wiegand) G.L.Nesom, family Asteraceae (first published in Phytologia 77(3): 287, as 'ontarione' (1995)) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Ontario Aster, so we can't confirm whether it is safe for cats and dogs. Checked against the ASPCA plant list; any other toxicity note on this page comes from PlantoScan's plant database.
- Photo: davecz2, CC BY-SA 4.0, Wikimedia Commons — original.
- Hardiness zone: USDA Zone 12a – 8b, calculated from the plant's minimum temperature.
- Care values(watering, light, temperature, humidity, soil, fertilizing): PlantoScan's plant database, filtered by automatic plausibility checks — values that fail them are hidden. How we source and check plant data.
Spotted a mistake? Email info@upvision.media with the page link — we check and correct reported errors.
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