Baton Rouge neighborhoods feature many mature oak trees. The full canopy of majestic live oak trees is an iconic symbol of southern Louisiana. Established oaks add a stately character to our southern landscape. Because of their beauty, strength, and longevity, live oak trees are highly desirable. However, it is often difficult to keep grass growing underneath many different types of mature oak trees, and homeowners struggle with this issue. But there are ways to approach this challenge and maintain the function of both the oak and the lawn.
Mature oaks cast shade and have an extensive root system that allows it to out-compete grasses for water and nutrients. Large, woody roots are often apparent right on the soil surface under oak trees. Most lawn grasses prefer full sun and have high water and fertilizer requirements, so they are fundamentally opposed in most ways.
Increase the amount of sunlight reaching the turf by selectively pruning trees. Lower tree branches and some of the inner branches may be trimmed and removed to allow more light to reach the lawn. This may be a solution for some oak trees, but doesn’t work with larger live oaks that have low, sprawling branches. Be aware that raising and thinning the canopy on large trees is best done by a professional arborist who can determine which branches should be removed without negatively affecting the longevity of a healthy tree. As the tree continues to grow over the years, shade may once again become a problem.
If the original grass is petering, one option is to replace your existing turf with a shade-tolerant variety. St. Augustine grass is considered the most shade-tolerant of the grasses used in Baton Rouge area lawns. However, St. Augustine requires some sunlight and will not flourish in heavy shade. Remove existing grass and add 2 to 4 inches of topsoil to plant new grass and promote growth. Do not pile several inches of soil up around the base of the tree trunk or on visible roots because this can lead to decay. Tilling the soil is not an option because of the damage that would occur to the oak’s roots.
If your oak tree filters out too much sun so that St. Augustine grass won’t grow, one solution is to apply a bed of mulch in the areas of heavy shade. A wide variety of mulch material can be applied 4 to 6 inches deep in the shady areas under a tree. This is by far the easiest and most inexpensive solution. Choose a mulch that works with your existing landscape.
• Pine Straw
• Shredded Hardwood-many different varieties of wood species and coloring
• Natural Leaves and lawn compost
Plant the area with a low-growing, shade-loving ground cover. Many shade-tolerant ground cover plants perform very well in Baton Rouge's humid climate with little to no maintenance. Ground covers can be planted in wide expansive design similar to grass. Typical shade-loving ground covers include:
• Monkey Grass (Ophiopogon japonicus)
• Creeping Lily Turf (Liriope spicata)
• Asian Jasmine (Trachelospermum asiaticum).
• Holly Fern (Cyrtomium falcatum)
• Leather Leaf Fern (Rumohra adiantiformis)
• Autumn Fern (Dryopteris erythrosora
• Sword Fern (Nephrolepis cordifolia)
• English Ivy (Hedera helix)
For a more involved solution, consider planting shrubs, annuals, and perennials that thrive in the shade. Incorporating your mature oaks into your existing landscaping beds will enhance the beauty of your yard.
Shade loving shrubs include Hollies, Azaleas, Nandinas, Cleyera, Ligustrum, Aucuba, Fatsia, Mahonia, Pittosporum, Hydrangea, Red Buckeye, Sasanqua, Camellia and many others.
For more colorful bedding plants, try Impatiens, Coleus, Wax Begonia, Browallia, Pentas, Salvias, Caladium, or Torenia.