Photo: Dr. Thomas G. Barnes - U.S. Fish and Wildlife Service Original uploader was Chhe at en.wikipediaPublic domainvia Wikimedia Commons
Aster saxicastellii Plant Care
Eurybia saxicastellii (J.J.N.Campb. & Medley) G.L.Nesom
Updated · Sources · How we source care data
Eurybia saxicastelli, commonly known as the Rockcastle aster, is an herbaceous perennial native to the south eastern United States. It is present only in the states of Kentucky and Tennessee along the Rockcastle River and the nearby Big South Fork River. As a result of its extremely restricted range as well as human alterations to its habitat, it is considered critically imperiled by the Nature Conservancy. The flowers appear in the late summer through fall and have ray florets that are pale blue to pale white and yellow disc florets that turn purplish with age.
Every 7–10 days
Full sun to partial shade
50–75°F
40–70%
At a glance
How do you care for Aster saxicastellii?
Water Aster saxicastellii 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 50–75°F (10–24°C) and 40–70% humidity. Fertilize it every 6 months during the growing season.
Where Is the Aster saxicastellii Native To?
What Is the Aster saxicastellii?
Aster saxicastellii (Eurybia saxicastellii) belongs to the Asteraceae family within the Eurybia genus. Aster saxicastellii is native to the south eastern United States.
Aster saxicastellii displays a clumping perennial growth habit, reaching up to 1.5 ft tall with a spread of approximately 1.5 ft. Aster saxicastellii produces daisy-like flowers in various colors.
Leaf size: approximately 4 inches.
How Often Should You Water a Aster saxicastellii?
Eurybia saxicastellii 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 Aster saxicastellii Need?
Aster saxicastellii thrives in full sun to partial shade.
Light Requirement
Full sun to partial shade
What Temperature and Humidity Does the Aster saxicastellii Prefer?
Eurybia saxicastellii grows best at temperatures of 50–75°F. Aster saxicastellii prefers humidity levels of 40–70%.
Temperature
50–75°F
Humidity
40–70%
What Soil Mix Works Best for a Aster saxicastellii?
Well-draining sandy loam with added organic matter. Good drainage is essential for Aster saxicastellii to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Aster saxicastellii?
Feed Aster saxicastellii 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 Aster saxicastellii?
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 Aster saxicastellii?
Aster saxicastellii can be propagated through division, seeds. Similar propagation techniques also apply to compact aster plant care, which shares the same genus.
Is the Aster saxicastellii Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Aster saxicastellii, 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 Aster saxicastellii?
Aster saxicastellii 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 Aster saxicastellii Need?
Aster saxicastellii grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. Aster saxicastellii is native to the south eastern United States. In cooler regions, grow Aster saxicastellii as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 12a
Keep exploring plants
Aster saxicastellii 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 Eurybia genus — compare its care with other Eurybia species on PlantoScan.
Eurybia is part of the Asteraceae plant family — browse all Asteraceae genera and species.
Aster saxicastellii thrives in bright light and direct sun — see other bright-light plants.
More Eurybia Species
Other Eurybia species in PlantoScan's care catalogue share similar watering, light, and soil preferences:
Sources
- Scientific name & taxonomy: Eurybia saxicastellii (J.J.N.Campb. & Medley) G.L.Nesom, family Asteraceae (first published in Phytologia 77: 261. 1995 [dt. Sep 1994; publ. on 31 Jan 1995]) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Aster saxicastellii, 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: Dr. Thomas G. Barnes - U.S. Fish and Wildlife Service Original uploader was Chhe at en.wikipedia, Public domain, Wikimedia Commons — original.
- Hardiness zone: USDA Zone 12a, 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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