SHADY LAWN PRODUCTION
by Jerry Parsons, Ph.D.
Horticulture Specialist, Texas Agricultural Extension Service
in San Antonio
lawns require special care to maintain satisfactory grass
cover. That means mowing higher and more frequently, watering
more often, giving particular attention to controlling leaf
diseases and removing fallen tree leaves.
Shaded turf is weakened by lack of sunlight
and competition for water nutrients from roots of trees and
shrubs. Thus, grass that is growing in shade generally is
shallow-rooted and is more succulent and less hardy than grass
growing in full sunlight.
As a result, the shaded grass is more susceptible
to drought stress and disease attacks. To reduce stress and
to promote healthy turf, mow the grass ½ to 1 inch
higher than grasses growing in full sunlight. Also, mow shaded
lawns frequently enough so that only 1/3 of the foliage is
removed at each mowing. Thus, grass mowed at a height of 2
inches should be mowed when it reaches 3 inches.
Because shaded turf is shallow-rooted and tree
roots are competing for available moisture, water more frequently
during drought stress periods. And, because grass growing
in shade is not able to utilize fertilizer as readily as grass
in full sunlight, fertilizer should be applied only in early
spring and fall.
Leaf diseases, particularly Gray Leaf Spot
and Helminthosporium, can seriously thin most lawn grass that
has been weakened by the effects of shade. So apply a fungicide
containing PCNB (Turfcide) or chlorothalonil (Daconil) to
shaded areas at monthly intervals during the growing season.
Severe disease infestations will require more frequent applications.
Treated areas should not be watered for 48 hours.
It's not a good idea to use chemicals for weed
control on St. Augustine grass in heavy shade because they
may further weaken the grass and increase its susceptibility
to disease. Trees and shrubs may also be damaged by some weed
Removing tree leaves that accumulate in the fall will also
help shaded grass.
In many home landscapes, shade develops to
such a degree that grass cannot be maintained. Even St. Augustine
grass, the most shade-tolerant of turf-grasses, requires at
least 30% direct sunlight to maintain satisfactory growth.
Consider replacing shaded grass areas with a bark mulch or
a ground cover.
* Use shade tolerant grasses, such as St. Augustine
* Raise the height of the mower blade 1 inch.
Instead of 1 ½ - 2 inches, mow up to 3 inches in height.
* Avoid excessive nitrogen which may promote diseases - particularly
* Avoid foot traffic in these areas.
* Select trees with more open crowns.
* Thin out crowns of existing trees to allow
more light to penetrate.
* Improve air movement by removing solid screens
*Remove fallen leaves promptly in the fall
* Prune tree limbs to a height of 8-10 feet
to permit more sunlight to reach the grass.
* If the above practices do not help, try some
of the shade-tolerant ground covers.
Ground covers are low growing plants that spread
by underground or above-ground stems that have an inherent
trailing growth habit. As these plants grow and develop, they
produce a continuous mat on the soil surface.
Ground cover plants may range from woody vines
to dwarf shrubs, depending on individual needs. Some of the
most prominent uses of ground covers in typical situations
are to cover bare areas of ground, prevent erosion of the
soil, add variety to the yard or garden; regulate foot traffic
in the yard or garden when used as edging for pathways, or
to tie together unrelated shrubs and flower beds in the landscape.
Ground covers are frequently used under or
around trees where grass grows poorly or where exposed tree
roots make mowing a hazard. Ground cover plants eliminate
the need for mowing as well as concealing the exposed tree
Many possibilities for living ground covers
are now available locally. For shade or partial shade, consider
vinca, Algerian ivy, English ivy, mondo grass, and Liriope.
Excellent choices for sunny locations include: Asiatic jasmine,
creeping junipers, purple leaf honeysuckle, Liriope, santolina,
and confederate jasmine.
Ground covers can be planted any time during
the growing season. Fall and spring plantings give best results
if potted or canned plants are used.
Ground covers are slower than grass in covering
bare ground. Consequently, weeds are likely to grow, especially
the first year. A mulch of bark, compost, or other organic
material will control most weeds, as well as retain moisture
in the soil. Pull the weeds by hand if they break through
the mulch or use a fusilade-containing product such as Ortho
Grass-B-Gon, which will kill all grass without damaging the
Water on a regular schedule throughout the
growing season, particularly during dry weather. During the
winter months, water the plants thoroughly when the weather
is dry and the temperature is above freezing.
Ground covers usually need pruning only to
removed dead wood and keep the plantings in bound.