Washingtonia robusta is not reliably hardy here but is a palm worth growing in Zones 7 and 8a. Each fall, I cut off all the fronds from the palm and cover it with a tarp for the winter. By summer, the palm has a full crown. The growth rate is unbelievable with close to 2 feet of trunk per year.
2005
2009
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Austin
Arkansas River Valley
Average January Low: 31°F, Average August High: 92°F
Extreme Winter Lows: 5-15°F, Extreme Summer Highs: 100-112°F, Annual Precipitation: 52 inches