For Release On Or After 02/28/14
By Dan Gill
LSU AgCenter Horticulturist
The next several months are a popular time for adding new beds of shrubs, ground covers and flowers to the landscape or reworking and replanting existing beds. When dealing with beds that are right next to your house, this work can affect your home’s termite protection.
We often refer to these plantings as “foundation plantings” or “foundation beds” in gardening – so named because they are meant to hide the foundation of the home. Beds in the landscape away from the house are not an issue. But when landscaping foundation beds, the LSU AgCenter provides a variety of recommendations to avoid negatively affecting termite protection.
Houses are typically protected from subterranean termite damage with chemical barrier-type soil treatments. Native subterranean termites always enter a home through the soil right next to a slab, pier or attached structure.
To protect the structure, the soil immediately next to the slab or piers is treated with a long-lasting liquid termiticide. Piers are also drilled with the termiticide injected into the inner void, and termiticides are also applied under the slabs of houses during construction. The treated soil next to the slab or piers is generally about 4 inches wide and about 6 inches deep. The presence of this chemical in the soil forms a protective shield that prevents termites from tunneling through the soil and entering the structure.
The soil in this area should never be disturbed or altered. It is all that stands between your house and a termite infestation. If anything is done to this soil, the barrier is compromised and the risk of termites entering the structure is increased.
During bed preparation for foundation plantings, it is imperative not to dig into the soil within 8 to 12 inches from the slab or piers. If new soil is being added to the bed, it should be kept away from and not allowed to cover the soil within 8 to 12 inches of the slab or piers. Either of these actions reduces or eliminates the effective barrier.
Shrubs next to the house should be located a minimum of 3 feet from the slab. This distance allows for growth of the shrubs over time. And the shrubs benefit from better light and air circulation that the space behind them provides.
This distance also keeps them from coming into contact with the house. Woody plants touching a structure may provide a route of entry to the structure for subterranean termites. Vines should not be allowed to grow on structures because they also may provide an entry route for subterranean termites.
In addition, inspection is a key tool for managing subterranean termites. Structures should be inspected for signs of subterranean termites at least once a year. If plants are close to the structure, it may be difficult to get behind them to inspect the slab or piers. This is particularly true of plants with thorns or spines.
Mulches are an important part of gardening in beds and provide numerous benefits. I encourage gardeners to use mulches with shrubs, flowers and vegetables and when establishing ground covers. But when mulches are applied to beds adjacent to your house and other structures, termite prevention needs to be considered.
Wood mulches should not be used next to the house because termites readily feed on them. Bark-based mulches are less favored by termites but still may be eaten. Pine straw is the most commonly used mulch that is lowest in cellulose and is a good choice for foundation plantings. Mulches that are not plant-based, such as rubber mulches, gravel and rocks, are, of course, not termite food.
The placement of the mulch is more important than what you use. You should never apply mulch right up to the slab or piers of a house. This forms a bridge over the chemical soil treatment, allowing the termites to bypass the barrier and enter the home. Keep mulches pulled back 8 to 12 inches to prevent this from happening. Mulches are not needed close to the structure if plants are planted the proper distance from the house.
More tips from the LSU AgCenter to minimize termite problems
– Place gutters and grade your landscape so water drains away from your house.
– Do not add fill dirt around the foundation or under porches or steps without contacting your termite company for retreatment.
– Promptly remove all scrap wood and wooden debris from the landscape.
– Use metal edging, decorative bricks or border plants to edge your beds. Avoid wooden materials that may serve as food for termites.
– When watering, avoid frequently spraying water against the foundation of your house. Adjust sprinklers so that they do not wet the sides of your house.
– Leave at least 2 inches of space between your house and a deck or other wooden structures outside. Wooden trellises with plants trained on them should be at least 6 to 8 inches away.
– Build decks and other structures on concrete pads and treat around the pads and posts. Treat under pads, too, and use pressure-treated wood in outdoor settings.
Rick Bogren