Is That a Geranium Tree? Hardy Pelargoniums in Southern Oregon

When Zonal Geraniums Grow into Woody "Trees"

Zonal geraniums (Pelargonium × hortorum) are hardy to ~28°F if acclimated slowly. In mild Southern Oregon winters, they can survive years, develop woody trunks, reach 7–8 ft, and self-sow.

How They Survive

• Gradual cooling triggers "antifreeze" solutes (sugars, salts) that lower cell freezing point.
• Ice forms between cells, not inside—prevents rupture.
• Your microclimate provides enough winter moderation.

Confirmation

Check Logee's catalog (search "Pelargonium") for "tree" or standard forms. Many are just old, large zonals trained to a single stem.

Care Tips

• Don't cut to ground—prune selectively to shape.
• Protect from hard freezes (<25°F) with frost cloth.
• Fertilize lightly in spring.