Allium macrum Plant Care
Allium macrum S.Watson
Updated · Sources · How we source care data
Allium macrum, the rock onion, is an American species of wild onion native to the eastern and central parts of the US States of Oregon and Washington. It grows on gravelly soils at elevations up to 1400 m.
Every 7–14 days
Full sun to partial shade
50–75°F
40–60%
At a glance
How do you care for Allium macrum?
Water Allium macrum every 7–14 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 40–60% humidity. Fertilize it every 6 months during the growing season. It is reported as toxic to pets, so keep it out of reach of pets.
Where Is the Allium macrum Native To?
What Is the Allium macrum?
Allium macrum (Allium macrum) belongs to the Amaryllidaceae family within the Allium genus. Allium macrum is native to the eastern and central parts of the US States of Oregon and Washington.
Allium macrum displays an upright, clumping perennial growth habit, reaching up to 2 ft tall with a spread of approximately 0.5 ft. Allium macrum produces spherical clusters of small purple, white, or pink flowers.
Leaf size: approximately 12 inches.
How Often Should You Water a Allium macrum?
Allium macrum requires watering every 7–14 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 7–14 days
Let soil partially dry between waterings
What Light Does the Allium macrum Need?
Allium macrum thrives in full sun to partial shade.
Light Requirement
Full sun to partial shade
What Temperature and Humidity Does the Allium macrum Prefer?
Allium macrum grows best at temperatures of 50–75°F. Allium macrum prefers humidity levels of 40–60%.
Temperature
50–75°F
Humidity
40–60%
What Soil Mix Works Best for a Allium macrum?
Well-draining sandy loam with added compost for nutrients. Good drainage is essential for Allium macrum to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Allium macrum?
Feed Allium macrum 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 Allium macrum?
Divide and repot every 3-4 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 Allium macrum?
Allium macrum can be propagated through division of bulbs, offsets, seeds. Similar propagation techniques also apply to onion plant care, which shares the same genus.
Is the Allium macrum Toxic to Pets and Children?
Toxic (caution)
Reported as toxic in our plant data. Not verified by the ASPCA.
Toxic to dogs, cats, and horses if ingested
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 Allium macrum?
Allium macrum is susceptible to onion thrips, onion maggots. 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 Allium macrum Need?
Allium macrum grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. Allium macrum is native to the eastern and central parts of the US States of Oregon and Washington. In cooler regions, grow Allium macrum as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 12a
Keep exploring plants
Allium macrum 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 Allium genus — compare its care with other Allium species on PlantoScan.
Allium is part of the Amaryllidaceae plant family — browse all Amaryllidaceae genera and species.
Allium macrum thrives in bright light and direct sun — see other bright-light plants.
More Allium Species
Other Allium species in PlantoScan's care catalogue share similar watering, light, and soil preferences:
Sources
- Scientific name & taxonomy: Allium macrum S.Watson, family Amaryllidaceae (first published in Proc. Amer. Acad. Arts 14: 233 (1879)) — World Flora Online record, IPNI name record.
- Pet toxicity: Allium macrum is reported as toxic to pets in our plant data (not verified by the ASPCA), so treat it with caution. Checked against the ASPCA plant list; any other toxicity note on this page comes from PlantoScan's plant database.
- 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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