Gardening Note # 16
Warm Season Grasses


Definition: Grasses that grow actively in summer and go dormant in cool weather. All warm season grasses turn tan-colored from November through April. Cool season grasses (Fescue, Kentucky bluegrass, etc.) thrive in cool weather and go semi-dormant in the hot summer months. Do not mix warm and cool season grasses in a lawn. Their cultural requirements are exactly opposite and neither will thrive well.

When: Warm season lawns may be started from seed while others must be sprigged. Whichever you choose, neither is done before all danger of frost is past, when temperatures are consistently in the 70's, usually in May in Cumberland County.

Soil Preparation for new lawns: PREPARING THE AREA IS THE MOST IMPORTANT STEP and is the same for whichever grass you choose. There are no short cuts, and there is no grass which will survive in our clay without proper soil preparation. Use a nonselective herbicide to kill existing weeds, observing waiting time on label before proceeding. Rototill the area 6-8" deep, add proper amounts of lime and fertilizer as determined by a soil test, and incorporate them thoroughly. Rake and level the area. Unless the entire potential root zone is uniformly limed and fertilized (if indicated), turfgrass roots will never successfully occupy this zone and will die during stress periods. Water immediately after planting and keep soil surface moist until plants are well established.

Renovating a lawn: Re-seeding or sprigging requires proper soil preparation also. Use an aerator or vigorously scratch soil with a rake so that seed/soil contact is made or to loosen soil for sprigs.

Thatch: is the accumulation of living and dead plant materials at the soil surface, plant parts shed by the grass plants as new parts are produced. Never allow thatch to exceed 1/2". Excessive thatch can prevent water and oxygen from reaching the roots, and both insects and diseases readily thrive in a thick thatch layer. Power rakes may be rented or you may mow closely and rake by hand.

Fertilizer: To determine amounts needed to apply 1 pound of Nitrogen to 1000 sf, divide 100 by the FIRST number on the bag. Ex: for 10-10-10 fertilizer, divide 100 by 10. The result is 10 pounds of fertilizer per 1000 sf. Timing and amounts are listed under individual grasses.

Weed Control: For either pre-emergent or post-emergent weed control, look for products labeled for your particular grass. Each grass has its own unique sensitivity and tolerance. Some labels say "for Southern Grasses" but you must be certain the label lists your grass and that you follow instructions exactly. Some products have specific precautions about use on newly-seeded lawns.

BERMUDAGRASS

Advantages: Good drought tolerance, good disease and wear resistance, quick to establish, well adapted to our soils. Bermuda is the only warm season grass you can overseed with ryegrass for a longer period of green. Others will be weakened by overseeding.
Disadvantages: Not very cold hardy, needs full sun (won't grow even in light shade), spreads aggressively into shrub beds.
Varieties: Common Bermudagrass: can be started from sprigs, sod, or seeds. Seeding rate is 1-2 lb. per 1000 sf. Needs less maintenance than hybrid cultivars. Tifway, Tifway II: best hybrids for most lawns. Especially useful for heavy traffic areas, playgrounds, golf fairways. Plant by sprigs.
Culture and Maintenance: Plant: seed or sprigs in May are best; no later than July. Mow: very low and often, without scalping, about 1" in height
Fertilize: 1 lb. nitrogen/1000 sf, starting in spring several weeks after grass turns green, then every 6 weeks through August. Fertilizing too early is harmful.
Lime: May need lime. Have soil tested every 2-3 years to determine needs. Can be applied at any time on established lawns but winter is the ideal time.
Water: 1" to 1-1/4" per week.
Weed Control: Look for products labeled for Bermudagrass. Pre-emergents: For some broadleaf weeds + crabgrass, goosegrass, foxtails: April Post-emergents: For broadleaf weeds, can be applied as needed, starting in May, several weeks after grass turns green.
Thatch: If necessary to de-thatch, hand- or power-rake in late spring/early summer.

ZOYSIA GRASS

Advantages: Soft, thick, chokes out weeds, tolerates drought, grows in sun or light shade, wear resistant low maintenance.
Disadvantages: Slow to establish (2-3 years); thatch may be a problem.
Varieties: Emerald: fine texture, good winter hardiness, shade tolerant. Meyer Z-52: Most cold tolerant, establishes fairly quickly, good for home lawns. Japonica: Coarse leaf, cold tolerant.
Culture and Maintenance: Plant: Sod or plugs in May. Seed may not be readily available. 4" plugs have best survival chance. Or buy sod and cut it up yourself. ("Bargain" ads are often for 1" or 2" plugs) Mow: Short: 1/2" to 1".
Fertilize: 1/2 lb. nitrogen/1000 sf after grass turns green in May; repeat in June and in August Mid-August is latest safe time. Zoysia is very sensitive to over-fertilizing. Lime: same as Bermuda grass.
Water: same as Bermuda grass.
Thatch: Has tendency to accumulate in zoysia. Needs de-thatching every 1-2 years by power- or hand-raking in late April.

CENTIPEDE GRASS

Advantages: Grows in acid soil, very low maintenance (less mowing, little or no fertilizer), grows in full sun to moderate shade.
Disadvantages: Does not tolerate drought, traffic, high pH, and is susceptible to pest-related problems and cold damage.
Culture and Maintenance: Plant: Seeding rate: 1/4 lb. per 1000 sf, or sprig in May. Mow: 1" height.
Fertilize: 1/2 lb. nitrogen per 1000 sf. ONCE A YEAR in June if needed. Will not tolerate excess nitrogen, nor fertilizing at wrong times. Have soil tested for proper amounts.
Lime: Do NOT lime unless recommended by a soil test.
Water: 1" per week.
Weed Control: Centipede is especially sensitive to certain herbicides; product must be labeled for Centipede grass. Pre-emergents: for some broadleaf weeds, crabgrass, goosegrass, foxtails: April. Post-emergents: for broadleaf weeds, use in May, several weeks after grass turns green, only as needed. Do not apply unless grass and weeds are actively growing.
Thatch: De-thatch in late May if necessary by power- or hand-raking.

ST. AUGUSTINE GRASS

Description: A coarse-leaf grass mostly adapted to sunny or shady areas in the Coastal Plain. Will also grow in well-drained soil in shade in Central Piedmont. Moderate to low wear resistance. Must plant sprigs. Variety: "Raleigh" variety is cold-tolerant cultivar with good disease resistance. Fertilizer: 1/2 lb. nitrogen per 1000 sf in May and again in June. Increase to 1 lb. nitrogen per 1000 sq. ft. in July, and revert to 1/2 lb.per 1000 sf in August.

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This information compiled by Cumberland County Master Gardeners.
This page was created on 4/22/98 using the Durham Master Gardener Homepage as a model. Our thanks to them and especially to Pauline Marx, Pam Reading and Eileen Lowenbach.