What grass grows best in Charleston, and when should sod go down?

The four grasses that do well here

Charleston lawns are warm-season grasses, and Clemson Extension compares the four common ones on the things that decide it: shade, salt, wear and upkeep.

• St. Augustine. The most shade-tolerant warm-season grass, though it still needs 4 to 6 hours of sun. Moderate upkeep, and it's planted as sod, sprigs or plugs. Its weak spot is chinch bugs, which Clemson calls its greatest disadvantage.
• Zoysia. Dense in full sun and part shade, thinner in deep shade, and it wears well. It's high-upkeep and slow to spread, which is why Clemson prefers sod for it.
• Centipede. Low upkeep, suited to infertile, acidic soil, and fair in shade. It handles salt poorly, doesn't stand up to heavy foot traffic, and too much fertilizer makes it less cold-hardy.
• Bermuda. Excellent wear, drought and salt tolerance, so Clemson calls it a good choice for oceanfront property. Very poor in shade, and its runners are hard to keep out of beds and walks.

Shade decides more than anything

Clemson's line is simple: under 4 hours of direct sun a day, it's too shady for grass to grow well. Under a big live oak the grass is also competing with the tree's roots for water and nutrients, and turf in shade tends to thin out year after year.

Where that's happening, the answer that lasts is usually a bed, not more sod: pine straw, mulch or groundcover over the roots. What not to do is level the ground under the tree with new soil. Clemson names grade changes, along with compaction and cut roots, as the three main causes of tree death during construction.

Lawn, bed, or both

What plants hold up to salt spray?

Clemson Extension's list for the South Carolina coast rates live oak, magnolia, yaupon holly, southern wax myrtle, sabal palmetto, pittosporum and oleander as highly salt tolerant: they grow where they take direct salt spray. Plants rated moderate do best sheltered behind those, a building or a dune. For lawns, Clemson rates centipede poorly for salt and calls Bermuda a good choice for oceanfront property.

When is the best time to lay sod in Charleston?

Spring or fall. Clemson Extension says sod is best laid in mid to late spring or in the fall, and in the fall early enough for it to root before cold weather. Summer sod can work, but it takes a lot of water. Sod laid in winter may or may not survive, depending on the temperatures.

Getting the ground ready

1. 1Test the soil 2 to 3 months ahead. Clemson notes that coastal soils in Charleston County can already be high in phosphorus, so the fertilizer should follow the test, not the bag.
2. 2Clear out the debris: old roots, rubble and dead turf.
3. 3Grade it so water runs away from the house, with the soil left about an inch below walks and drives.
4. 4Loosen compacted soil, work any lime or fertilizer the test calls for into the top 4 to 6 inches, and firm it with a roller.
5. 5Lay the sod within 48 hours of delivery, seams tight and staggered and never stretched, then roll it.

How much should the yard slope away from the house?

The residential building code's minimum is 6 inches of fall within the first 10 feet out from the foundation (IRC R401.3). Where the lot is too tight or too flat to get that, a swale or a drain has to carry the water away instead.

The first few weeks

Water new sod to a depth of about 4 inches right after it goes down. Through the first week, if rain doesn't do it, water daily or as often as it takes, and don't let it dry out until it has rooted into the soil underneath.

What Josiah looks at on a visit

How many hours of direct sun the spot really gets, how close the roots run to the surface, and where the lawn could stay.