Question
QUESTION: I need advice.  Two months ago we bought a home with a liquidamber tree in the front yard.  The previous owners had done NOTHING with the landscaping, and the neighbors told me that they even parked their cars on the front lawn (on the tree's roots)! Here's the question:  The tree roots are up to the surface.  There are sprinklers.  No grass.  I'd like to figure out what to do under this tree.  It looks like there was an attempt at a lawn at some time as there is sod netting mixed in with the dirt (lovely).  I had a gardener clean up man over to do some clean up of some stumps.  I asked about the lawn and he said, "if you want a grass lawn, you'll need to get rid of the tree".  I like the tree.  that's not an option.  I've looked at landscaping books to try to find what would work best under the tree.  Would clearing surface roots harm the tree?  Are there some ground covers that maybe might work well with it?  The tree is about 25 ft. tall.  Any advice you can give would be appreciate.

ANSWER: If the roots are above the ground you can add a inch not more than 2 of sand over the roots. Then put sod on top of the sand. If you cut the surface roots this will harm the tree.

The lack of grass is due to the shade Mianly Some grasses will grow under  shade while others need full sunlight.
Trees and shade create a naturally pleasing environment in the landscape. However, it is difficult to grow grass under trees because not only the quantity but also the quality of the light changes in the shade. In full sun, light is in the "near red" range of wavelengths; in the shade it shifts to the "far red," which is less effective in photosynthesis. In addition, dense canopies, particularly those of conifers, filter out the blue component of sunlight, which is critical for plant growth. The result of these changes is a reduction in photosynthesis and its products, including carbohydrates needed for plant growth.

Leaves, leaf cuticles and stems of plants are thinner in shade. Shoot density decreases and rhizome and stolon numbers decrease. Plant tissues are succulent and there is an increase in susceptibility to environmental stresses and disease. Transpired moisture from trees and grass, and moisture from dew forming under trees, take longer to dissipate, and the additional moisture may contribute to an increase in disease.

Shady conditions in combination with other plant stresses contribute to the difficulty of growing grasses under trees. For example, tree roots compete with turf for water and nutrients, and this competition can further weaken turf growing in shade. Allelopathic effects, such as the inhibitory effect of silver maple upon Kentucky bluegrass, are important between certain species of plants. Excessive organic matter from leaf litter will also inhibit grass. One or more of these factors make it particularly difficult to grow grass under sweet gum, maple and unpruned pin oak. On the other hand, grass is easier to grow under locust and poplar trees.


Select and use grasses that have improved shade tolerance  Most of the fine fescues (hard, sheep, spreading, slender creeping and Chewing's) have very good shade tolerance. Tall fescue has good shade tolerance, while Kentucky bluegrass is the least shade tolerant of the cool-season grasses. Bermudagrass, zoysiagrass and buffalograss should not be used in shady locations. In areas where shade-tolerant grasses fail, consider shade-tolerant groundcovers or mulched beds instead of grass.

If you want to use ground cover instead you might try Vinca minor .
Vinca minor vines require good drainage. Plant in partial sun to full shade. Good choice for a ground cover for an area with dry shade; while the plant will grow more vigorously in moist soils, Vinca minor vines are reasonably drought-tolerant once established. Achieving vigorous growth is usually not a problem for these plants.
Vinca minor vines are considered somewhat invasive plants, so, if this is a concern for you, make it a point each year to keep their runners in check. But remember, the flip side of the coin for so-called "invasive plants" is that they are vigorous growers, meaning that they tend to be successful at filling in an area -- which is what you want out of a ground cover. If you use vinca minor
add potting soil to the sand mixture so it will have a good soil to grow in.



---------- FOLLOW-UP ----------

QUESTION: wow..thanks for the info.  The tree is not very dense with foliage though, and the grass area seems to be in almost full sun.  I'm in Southern California...so temps are hot and dry.  I'm glad you told me about not cutting the roots.  We'll try the sand/soil addition. I'm interested in the ground cover option, but I don't think that Vinca Minor would work because of the full sun and high temps.  What do you think?

Answer
The full sunlight would give vinca problems. If there is that much sunlight grass should not be a problem to grow.
Here is a newer plant that some are using as a ground cover. I would suggest that you visit a local nursery and ask them what would be good for your situation and locale.
An Australian native proving its worth in California gardens is Scaevola (skeevola) 'Mauve Clusters'. This lush but tough ground cover, recently introduced by the UC Santa Cruz Arboretum, resists pests, tolerates moderate frost and drought, holds down weeds, requires little maintenance, and has an unusually long blooming period.

'Mauve Clusters' looks like a succulent dwarf coyote brush (Baccharis pilularis) with fan flowers--half-circles of bluish purple petals--sprinkled over its foliage. Like coyote brush, this compact shrub does well at choking out weeds and is almost maintenance-free.

Give it infrequent but consistent watering--once it is established, two soakings a month will do.

Though this scaevola doesn't require much fertilizer, iron sulfate enhances its flower color. Along the coast, it bears lavender blooms nearly all year. It can grow in any good garden soil and is hardy to 25[deg.] or less. In California, it has no known pests.

To use scaevola as a ground cover, set plants about 3 feet apart. Each will eventually spread 3 to 5 feet, forming a 4- to 6-inch-high mat.