Outdoor verdict
Macarthur palm lives outside only in a mild winter, about 28F (USDA 10a+). A real freeze marks it. Young plants can wait in a pot. A mature one wants the ground only if the winter clears that number.
The clustering Macarthur palm of tropical streets and atriums. USDA 10a to 12. Kew's accepted name is Ptychosperma propinquum. Nurseries still use macarthurii.
Cold hardiness
Survives about 28°F / -2°C. Outdoor range USDA 10a–12a. Hover or click a zone, state, or country. Click a state to open palms that grow there.
Highlighted USDA zones 10a–12a. Green countries can be grown outdoors.
United States
In range Too cold
World
Native Can be grown
Alaska and Hawaii are state outlines with their overall zone range. A country is painted if its mildest inhabited winter is at least one USDA step milder than this palm’s hardiness.
Winter care
Drainage matters more than a blanket. Soil: Rich, moist, well-drained. Water: Moist but never waterlogged (mesic). Wrapping does not buy an extra zone. If the winter is colder than the kill number, keep it in a pot.
Scientific facts
- Clustering, slender, with a small crownshaft and jagged leaflet tips.
- Kew lumps the old macarthurii name under P. propinquum. Some nursery stock is other Ptychosperma.
- Frost-free. Not a zone 9 street tree.
Region of origin
New Guinea to northern Australia
Native countries
Historical discovery
Gardens have sold it as Ptychosperma macarthurii for more than a century. Kew now accepts Ptychosperma propinquum. Clustering slender trunks and red fruit are the look.
Names
Common names
Macarthur palm, MacArthur palm, Horseshoe palm
Synonyms
- Ptychosperma macarthurii (H.Wendl. ex H.J.Veitch) H.Wendl. ex Hook.f.
Full care guide
The Macarthur palm is a clustering Ptychosperma sold for tropical streets and bright atriums. USDA 10a to 12. Kew's accepted name is Ptychosperma propinquum. Labels still say P. macarthurii. It wants heat and water, not a freeze.
Growth Rate:
Moderate to fast in heat.
Fruit and Flowering:
Orange to red. Messy on walks. Birds like them.
Light Requirements:
Full sun to light shade in the humid tropics. Young plants like a little protection from dry inland sun.
Water Requirements:
Even moisture.
Maintenance Level:
Medium. Thin crowded canes if you want. Feed in the growing season with palm-specific fertilizer. Fruit drop is the mess.
Common Diseases/Pests:
Scale, mites in dry wind, and nutrient yellowing in sand.
Plant Care:
Heat, water, frost-free. If your winter still freezes, this is the wrong clustering palm. Try lady palm or European fan instead.
Macarthur palm Frequently Asked Questions:
Plant Macarthur palm in genuine tropical heat as a clustering street or atrium palm. If the tag is the only reason you wanted it in zone 9, pick a hardy clump instead.
Macarthur palm questions
Will Macarthur palm live outside?
Yes, if winter stays above about 28F (USDA 10a+). Below that number it belongs in a pot.
What do nurseries mislabel Macarthur palm as?
Common names wander. The accepted name is Ptychosperma propinquum. Read the Latin on the tag before you buy.
Pot or ground for Macarthur palm in a cold state?
Start it in a pot if you want. The ground is fine only where winter stays above about 28F.
Why does Kew say propinquum?
Palms of New Guinea (2024) treats macarthurii as a synonym of Ptychosperma propinquum. Shops have not caught up.
Macarthur or solitaire palm?
Solitaire is Ptychosperma elegans, usually a single trunk. Macarthur is the clustering one.
Good indoor palm?
A young plant in a bright, humid space. It wants to be a courtyard clump.
Related palms
The mix-up, the substitute, then nearby hardiness.
