Shaded trees

Shade trees grow up to do exactly what they were planted to do — create shade. Over time, bare spots may develop in lawns because of excessive shade.

I commonly hear from gardeners who complain that grass won’t grow under a tree no matter what they do. When I mention that the shade created by the tree is the likely problem, the standard response is that grass always grew there before.

What they likely do not realize is that as trees grow, shade created by a tree increases from year to year. Here’s a basic lesson in horticulture: shade trees grow up to do exactly what they were planted to do — create shade. Eventually, areas where grass had always grown well before will no longer receive sufficient sunlight for lawn grass to grow.

Bare areas occur under and around trees because conditions eventually become too shady for grass to thrive there. Eventually, even an area where grass has always grown well before will no longer get enough sun.

If you are trying to deal with this sort of situation, here are some things you can do.

The amount of sunlight reaching the turf can be increased by selectively pruning trees in your landscape. The lower branches and some of the inner branches may be pruned to allow more light to reach the lawn below. Keep in mind that raising and thinning the canopy on older, mature trees is often done best by a professional arborist who can determine which branches should be removed without adversely affecting the tree.

After pruning is done, the existing grass will (hopefully) do better. Or if the grass has died out in the area, you can lay new sod. But remember the tree will continue to grow and this should be considered, at best, a temporary solution.

St. Augustine is the most shade-tolerant grass for our area. Understand that the term “tolerant” does not mean this grass thrives in the shade. All of our lawn grasses prefer full sun; it’s just that St. Augustine will do better than others with some shade during the day.

Grass growing in shaded areas should be mowed at a slightly higher setting on your lawn mower than normally recommended. This allows the leaf blades to grow longer and therefore have more surface area to absorb what light is available and produce food through photosynthesis. St. Augustine can be mowed at a height of 3 inches.

If after these efforts you still can’t get grass to grow under your tree, it’s time to accept the situation and stop wasting your time and money trying to make grass grow where it can’t.

Unless cutting down the tree is an option, you have two basic options: cover the area with a few inches of mulch or look at the area as an outstanding opportunity to create a new garden with shade-tolerant plants.

The most important thing to remember when creating a landscaped area under a tree is to respect the root system of the tree itself. Here are some tips:

• Avoid severing any roots larger than 1 inch in diameter.

• Use a garden fork to turn the soil under the tree rather than a shoved or spade, since the fork will cut or injure fewer roots.

• If you need to bring in extra soil to create the bed, use as little as possible — preferably no more than 2 inches of a garden soil mix (not top soil) fill annually.

• Don’t pile several inches of soil around the base of the trunk of the tree, because this can lead to the decline of the tree.

• The simplest solution is to plant the area entirely with a low-growing ground cover. I think the two best ground covers for covering large areas are monkey grass (Ophiopogon japonicus) and Asian jasmine (Trachelospermum asiaticum). These ground covers are reliable, easy to grow and relatively fast spreading.

Other ground covers suitable for larger areas include ferns, such as holly fern, autumn fern, wood fern and many others; English ivy; liriope (Liriope muscari); Algerian ivy; and asparagus fern (Asparagus sprengeri).

Many other plants also thrive in partially shaded to shady conditions. For colorful bedding plants try impatiens, wax begonias and caladiums. Shade-tolerant perennials include indigo, ligularia, aspidistra, ajuga, cardinal flower, violets and the many gingers, to name a few.

When the lawn grass finally “decides” that an area has become too shady for it to grow there anymore, don’t fight it. Instead, open yourself up to the wonderful possibilities of planting a beautiful and satisfying garden of shade-loving plants.

Dr. William Johnson is a horticulturist with the Galveston County Office of Texas AgriLife Extension Service, The Texas A&M System. Visit his website at

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