Richard Bogren | 7/11/2019 7:44:55 PM
LSU AgCenter Horticulturist
(07/12/19) Do you have trouble with grass underneath large shade trees in your landscape? Or no grass at all? This is a common problem for those of us fortunate enough to have such large shade trees. While these large trees provide much needed shade and a home for birds, squirrels and other wildlife, they tend to shade out the sunlight that grass needs to grow.
One thing that can take the heat and sun we are so fortunate to get here in Louisiana and do so with great vigor is turfgrass. However, we are met with a conundrum in that we want our grass but we want our shade, too. It’s kind of like that old saying of having our cake and eating it too. But we cannot force plants to grow where they are not intended to grow. The good news is, we’ve got options — there are 391,000 named plants and thousands new species are found each year. But let’s stick to the ones we can get our hands on.
One option for this shady situation is to plant the area with a shade-tolerant ground cover or even landscape it with shrubs, annuals and perennials that thrive in shade. If you want to stick with the concept or look of a grass, a great substitute is to plant the area with a low-growing ground cover.
Some of your options for covering larger areas with ground covers include monkey grass (Ophiopogon japonicus), creeping lily turf (Liriope spicata), coral bells Heuchera (Heuchera, spp.) that is a native of North America, Asian jasmine (Trachelospermum asiaticum), English ivy (Hedera helix) and Japanese ardisia (Ardisia japonica). Another choice is vinca (Vinca minor), and it has flowers.
Ferns are another option that’s often found growing naturally in heavily shaded forests. Choices include maidenhair fern, lady fern and oak fern. And one cannot forget the resurrection fern. Some others that are commonly used, although most are non-native, are autumn fern (Dryopteris erythrosora) holly ferns (Cyrtomium falcatum), leather leaf fern (Rumohra adiantiformis) and sword fern (Nephrolepis cordifolia) with others also being available. Most of these ground covers are reliable, easy-to-grow, fast-growing and reliably found in local nurseries.
Other plants to consider are black snakeroot, also known as black cohosh (Cimicifuga ramosa) a native perennial of North America, caladiums (Caladium sp.), wild ginger (Asarum splendens) and ligularia (Ligularia sp.). Plants like caladiums, gingers and ligularia can be readily found in local nurseries while the more-native plants sadly are not as available. Call your local nurseries to check availability or try online websites.
Be aware that when planting around trees it is very important to remember the root system of the tree itself. You do not want to damage a large tree’s root system, especially in areas like Louisiana that are often hit by tropical storms, tornados and hurricanes. When possible, try to avoid cutting any roots larger than 1 inch in diameter. This can be done more easily by using a gardening fork rather than a shovel to turn the soil under the tree. The fork will damage fewer roots as you work the area to prepare to plant.
Additionally, consider the possibility of trunk decay if you decide you need to bring in more soil or amend what is currently present. When you pile too much soil around the trunk and root area, the trunk has a tendency to decay. If you need to bring in extra soil to amend or create a bed, use as little as possible. We like to suggest no more than 2 to 4 inches deep. If you intend to cover a large area of the tree’s root system extending out well beyond the reach of the branches, limit it to a 2-inch thickness.
You have so many plants to consider when working and planting in a partially to fully shaded area. And in this hot weather of summer, I couldn’t think of a nicer place to garden than in the shade. Not only does the shade make the heat more tolerable for us, it does so for the plants, too. And the shade also makes it tougher for weeds, especially those that thrive in full sun. Don’t fight your lawn when an area has become too shady. I find that Mother Nature often gets the upper hand when it comes to these types of things. It’s best to work with her, rather than against her.
If you find that planting is more than you want to do and the grass-barren area has become too unsightly, a final and relatively cheap and easy solution is to simply mulch the area. Leaves, pine straw or other mulching materials can be applied 4 to 6 inches deep under a tree where grass no longer grows well. Mulch has many benefits. It helps retain moisture for the roots of the trees, slows the growth and sometimes prevents weeds, and adds organic matter to the soil as it decomposes. It also looks very attractive and natural. As the years go by and the mulch settles, you can simply add more mulch to maintain a 4-inch to 6-inch depth.
Asian jasmine grows under a large live oak tree outside J.C. Miller Hall on the LSU Campus in Baton Rouge. Photo by Heather Kirk-Ballard/LSU AgCenter
English ivy is a classic plant for shady areas, although it often is an invasive grower. Photo by Heather Kirk-Ballard/LSU AgCenter.
Gingers can be a great choice for creating interest and replacing poorly growing grass in a shaded area. Photo by Heather Kirk-Ballard/LSU AgCenter