Ask Mr. Smarty Plants

That is an excellent choice for an Eagle Scout project, and we congratulate you. As you may know, the Lady Bird Johnson Wildflower Center focuses on the use, care and propagation of plants native not only to North America but to the area in which the plants are being grown. We do this because native plants will require less water, fertilization and maintenance, as well as continue to provide sustenance and shelter to native birds and butterflies. We are assuming you would like to have an evergreen plant, if some can be found that will do well in your area, in order for the protection to be year-round.The evergreen part can present some difficulties, as you are in USDA Hardiness Zone 6b, which means you can have average annual minimum temperatures of -5 to 0 deg. F. Another problem is the height; most evergreen shrubs are going to get taller than that, and require continual pruning to keep them at that height. And our favorite evergreen shrub for the Northeast, Arctostaphylos uva-ursi (kinnikinnick), with glossy evergreen leaves and red fruit, seldom gets over 1 ft. tall, and is considered a trailing ground cover, not suitable for your purposes. Follow each link to the page on that plant to see what light requirements it has, water use, expected height, etc. If you decide you could use a deciduous shrub; that is, not evergreen, you can go back to our Native Plant Database, search on Connecticut and "shrub" under General Appearance, and make your own selection. 

Barrier hedge shrubs for Darien, CT:

Ilex glabra (inkberry)

Ilex laevigata (smooth winterberry) - pictures

Juniperus communis var. depressa (common juniper)

Morella pensylvanica (northern bayberry) - pictures

From our Native Plant Image Gallery:

Arctostaphylos uva-ursi

Ilex glabra

Morella pensylvanica