Mountain Phlox Plant Care
Phlox austromontana Coville
Updated · Sources · How we source care data
Phlox austromontana is a species of phlox known by the common name mountain phlox. It is native to the southwestern United States and Baja California, where it grows in forested and wooded mountain habitat, scrub, and open areas.
Every 7–10 days
Full sun to partial shade
60–75°F
40–60%
At a glance
How do you care for Mountain Phlox?
Water Mountain Phlox 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 60–75°F (16–24°C) and 40–60% humidity. Fertilize it every 6 months during the growing season.
Where Is the Mountain Phlox Native To?
What Is the Mountain Phlox?
Mountain Phlox (Phlox austromontana) belongs to the Polemoniaceae family within the Phlox genus. Mountain Phlox is native to the southwestern United States and Baja California.
Mountain Phlox displays a clumping perennial growth habit, reaching up to 1.5 ft tall with a spread of approximately 1 ft. Mountain Phlox produces colorful clusters of small, star-shaped flowers.
Leaf size: approximately 2 inches.
How Often Should You Water a Mountain Phlox?
Phlox austromontana 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 Mountain Phlox Need?
Mountain Phlox thrives in full sun to partial shade.
Light Requirement
Full sun to partial shade
What Temperature and Humidity Does the Mountain Phlox Prefer?
Phlox austromontana grows best at temperatures of 60–75°F. Mountain Phlox prefers humidity levels of 40–60%.
Temperature
60–75°F
Humidity
40–60%
What Soil Mix Works Best for a Mountain Phlox?
Well-draining, fertile soil with a neutral pH. Good drainage is essential for Mountain Phlox to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Mountain Phlox?
Feed Mountain Phlox 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 Mountain Phlox?
Divide and replant every 3-4 years. 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 Mountain Phlox?
Mountain Phlox can be propagated through seeds, division. Similar propagation techniques also apply to annual phlox plant care, which shares the same genus.
Is the Mountain Phlox Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Mountain Phlox, 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 Mountain Phlox?
Mountain Phlox is susceptible to aphids, spider mites. 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 Mountain Phlox Need?
Mountain Phlox grows outdoors in USDA Zone 13a. It survives winters down to planting zone 13a. Mountain Phlox is native to the southwestern United States and Baja California. In cooler regions, grow Mountain Phlox as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 13a
Keep exploring plants
Mountain Phlox 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 Phlox genus — compare its care with other Phlox species on PlantoScan.
Phlox is part of the Polemoniaceae plant family — browse all Polemoniaceae genera and species.
Mountain Phlox thrives in bright light and direct sun — see other bright-light plants.
More Phlox Species
Other Phlox species in PlantoScan's care catalogue share similar watering, light, and soil preferences:
Sources
- Scientific name & taxonomy: Phlox austromontana Coville, family Polemoniaceae (first published in Contr. U.S. Natl. Herb. 4: 151 (1893)) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Mountain Phlox, 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.
- Hardiness zone: USDA Zone 13a, 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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