The “mazari palm” from Afghanistan is probably one of the cold hardiest palms that we have, and is adaptable to zones 8 through 11 and known to have survived in zone 7. It’s a clustering palm whose trunk is normally subterranean but occasionally comes out of the ground to a maximum height of about 7 feet. It’s very slow growing with leaves that are about 4 feet across and range from blue green to a silvery blue similar to bismarkia. Mature clumps are most likely to be around six feet tall and eight feet wide it’s extremely drought tolerant which translates into a requirement of extremely well draining soil.