Ask Mr. Smarty Plants

Sounds like an excellent retirement project and, fortunately, there are several evergreen shrubs that grow well in Central Texas that should serve your purposes. However, we are a little concerned about your desire to prune up to 18" from the fence. Are you saying that the total depth of the shrub is going to be 18"? In the first place, these are all moderately to fast-growing, and that is going to take a lot of pruning. In the second place, if you do, indeed, prune it that much, your plants will be constantly struggling to keep putting on new growth and leaves to maintain nutrition. They probably never will have enough energy to produce berries, which attract wildlife, and will not provide adequate cover for birds to nest or just hide from predators. If your property extends beyond the security fence, perhaps the shrubs could be on the outside and further from the fence, to permit them to fill in naturally. They would still provide the sound dampening, protect your house from view, and invite the birds.  Of course, if you prefer to have them inside the fence, you could still allow them to grow an adequate depth for flourishing, but it is going to intrude a little bit more on your garden space inside the fence.

If you are interested in birds, you will want berry-producing plants. Five of these plants do so, but only on the females. One, Leucophyllum frutescens (Texas barometer bush), does not produce berries but is a nectar source and provides nesting sites and cover. The others are all dioecious, which means there must be at least one male of the same species within 30 to 40 feet for pollination in order for the berries to develop on the females. All of these shrubs are evergreen, and three of them can get up to at least 12 feet tall. The mahonias are the "thorny" type plants you mentioned, and ordinarily only grow  4 to 6 feet in height. The nurseries from which you purchase the plants should have suitable distances between the shrubs to suggest, but a pretty standard distance between hedge shrubs is about 5 to 6 feet, If you have difficulty locating suppliers for these Texas native plants, go to our Native Plant Supplier section, type in your town and state, and you will get a list of native plant nurseries, seed suppliers and landscape consultants in your general area.

Leucophyllum frutescens (Texas barometer bush)- 5 to 8 ft.

Mahonia trifoliolata (agarita)- 3 to 6 ft.

Mahonia swaseyi (Texas barberry)- 3 to 4 ft.

Ilex vomitoria (yaupon)- 12 to 25 ft,

Rhus virens (evergreen sumac)- 8 to 12 ft.

Morella cerifera (wax myrtle) - 6 to 12 ft.

Leucophyllum frutescens

Mahonia trifoliolata

Mahonia swaseyi

Ilex vomitoria

Rhus virens

Morella cerifera