Growing grass under trees is a constant battle.
So why fight it? Grass grows more naturally in prairies than in forests. Sunlight is key. Some lawn grasses are shade-tolerant but can’t really be called shade-loving. Prairie grasses survive low water conditions, but a big tree takes enormous amounts of water away from your lawn grass.
Ground covers are a lower maintenance alternative to grass. The term applies to a wide range of low-growing spreading plants including perennials, vines and even shrubs.
The first ground cover that comes to most people’s minds is liriope, commonly called monkey grass. In Midtown I’ve seen several attractive front yards where the sunny part has turf and the area under a large tree has a neat bed of dark green monkey grass. Because it spreads so vigorously, this monkey grass is great for filling in an area but will bully other plants if you try to use it along the edge of a bed. Variegated monkey grass is less aggressive, so chose the type of plant based on its intended use.
When planting any ground cover under a tree, respect the tree’s network of small feeder roots. This means you should do no large-scale tilling anywhere under the tree’s dripline. If the area has patchy grass that needs to be removed before you plant the ground cover, use a general herbicide or one specific to grass. Wait for the herbicide to work, and then plant the ground cover in plugs with mulch in between. To fill in well, different ground covers require difference spacing, information you can get by reading the plant tag, asking the nurseryman, or doing your own research.
Ground covers respect the need of some trees to have exposed roots that should not be smothered with a heavy layer of sod. If someone has limbed up a Southern magnolia, a practice I compare to shortening a Southern belle’s hooped skirt, plugs of monkey grass or other ground cover in little pockets of soil between the exposed roots can help restore the tree’s modesty.
Other common ground covers for shade include vinca minor (periwinkle), ivy, pachysandra, ajuga (bugleweed), and creeping jenny. In two heavily wooded lots in East Memphis, I’ve seen moss used successfully as a ground cover. The wide-spread coverage makes it obvious that the moss was planted intentionally. The homeowners keep the areas cleared of brush and fallen leaves, but they don’t need to own a lawnmower.
If you have more than one large tree, consider replicating a small forest environment using small understory trees, shade-loving shrubs, perennials, and mulch. Tour the woodland garden at Dixon Gallery and Gardens for inspiration.
Non-organic mulching materials can help cover some areas beneath a tree as long as they allow water to reach the roots. My shade garden includes a wide path of pea gravel, but I would not go as far as one gardener who converted his entire front yard to pea gravel. The next homeowner returned the yard to more plant-based alternatives.