Ask Mr. Smarty Plants

Starting with the last question first, the Lady Bird Johnson Wildflower Center is dedicated to the use, protection and propagation of plants native not only to North Amerca but to the area in which the plants are being grown. Cupressus sempervirens, Italian Blue Cypress, is native to Africa, Temperate Asia (including, of course, Cyprus) and Greece. Here is an extract from a USDA Forest Service website Cupressus Sempervirens:

"Italian Cypress is often used for framing, as a strong accent around large buildings, or in the formal landscape but does not lend itself well to many home landscapes. It quickly grows much too tall for most residential landscapes, looking much like a green telephone pole." The article also says that if they are planted 3 ft. apart, they make a dense screen.

Going back to a native plant, Prunus caroliniana (Carolina laurelcherry), we have another quotation, this time from a previous Mr. Smarty Plants answer:

"Although a little west of its eastern limit, Prunus caroliniana (Carolina laurelcherry) would be a good choice for a small evergreen tree in your landscape. You might also consider Ilex vomitoria (yaupon)." 

As a general rule, the diameter of a shrub is about equal to the height of the shrub. In other words, if you have a six-foot tall shrub, it should spread about three feet in every direction for a total of 6 feet in diameter. So, if you want a screen effect, a distance of 5 to 6 ft., trunk to trunk would allow the outer tips of the shrubs to mesh. You can plant them closer if you wish, but they would begin to shade each other, and the interiors of the plants would become scraggly and less of a screen. 

Pictures of Cupressus sempervirens from Google

From our Native Plant Image Gallery:

Prunus caroliniana

Prunus caroliniana

Ilex vomitoria

Ilex vomitoria