A visit to Charleston, S.C., especially during spring, is bound to get your green thumb itching. But it's best not to get too excited. Western Pennsylvania is in USDA Hardiness Zones 5 and 6, which means temperatures can fall to minus 10 degrees.

Charleston, however, is in Zone 8, where the average minimum temperature is 10 degrees above zero. Simply put, it's too cold here for many Southern plants to survive outside.

Take, for instance, the lush Camellia japonica that make Magnolia and Middleton Place plantations such beautiful places to visit in early spring. These flowering evergreen shrubs, which are native to the Far East and first planted in Charleston in the 1820s, require a warm-climate landscape.

The same goes for the magnificent Southern live oaks that so many of us associate with Southern cities. While live oak is able to withstand hurricane-force winds and heavy rains and is extremely long lived, it is also extremely susceptible to freeze damage. Ditto with the Spanish moss that hangs like long beards from its branches. (Which, by the way, is not really moss at all but an epiphyte.)

Oleander is another pretty plant that grows especially well in the coastal areas of South Carolina. In May, the ornamental shrub erupts with distinctive and sweet-smelling pink flowers. But because it's cold hardy to zone 7, it won't grow here. But maybe that's a good thing -- its leaves and branches are extremely poisonous. (Legend has it that local Charleston women used oleander to make a tea that was served to British soldiers during the Revolutionary War.)

But what if you're determined to landscape with palms, another Southern favorite? Your best bet is the Needle palm, considered the world's hardiest palm. Even though it's native to South Carolina, it can tolerate temperatures as low as minus 23 degrees. It might not be as pretty as the iconic Palmetto palm (zone 7 and 8), which grows up to 65 feet. But its spikey green leaves will definitely make your Pittsburgh garden look more exotic.