Specifications for Turfgrass Establishment
Texas Cooperative Extension
Text and images copyright © Richard Duble.
Turfgrass has become increasingly important in today's society as people's
needs increase for recreation, comfort and conservation. Turfgrasses enhance
the appearance and utility of sports fields, lawns, parks, golf courses
and other greenbelt areas in and around urban centers. They improve the
environment of urban centers by reducing erosion, temperatures, noise, dust
and glare. And, turfgrasses improve the safety of sports fields and playgrounds
by adding resiliency to the playing surface.
Successful establishment of a turfgrass on a sports field, lawn, park, golf course or other site involves four critical steps - (1) proper site preparation, (2) selection of an adapted turfgrass, (3) planting the turfgrass and (4) post planting care and maintenance.
Site PreparationProper site preparation is essential to the successful establishment of a turfgrass. As the foundation is the strength of a building, the seedbed is the support for a turfgrass. The seedbed refers to the several surface inches of soil that are tilled and, perhaps, modified prior to planting. Poor seedbed conditions, like a faulty foundation, result in long term maintenance problems for the turf manager. Water management is also complicated by poor seedbed preparation. And sites with severe slopes, shallow topsoils or compacted soils need modifying or amending before a turfgrass is planted to make water management more efficient.
Site Clearing. The first step to prepare a site for planting is to remove all debris - construction residues, rocks, tree stumps, undesirable grasses and weeds. Construction crews often leave sand, concrete and other building materials that get covered up or buried during construction. Removal of these residues creates a more desirable and uniform seedbed for planting. Common problems found at new sites include concrete layers where cement was mixed and became covered with topsoil, buried bricks and wood, and pockets of sand or gravel where concrete was mixed. All of these products create unfavorable conditions for turfgrasses and usually result in dry spots that are difficult to maintain.
Remove rocks and gravel from the upper 2 inches of soil to provide a uniform soil medium for grass root development. Where large deposits of rocks are found, the entire deposit of material may need replacing. For large sites such as sports fields and golf courses, rock-picking machines are available to remove rocks from the surface prior to planting.
Tree stumps and other organic debris should be removed rather than covered with topsoil. Decaying organic residues frequently result in "fairy rings" with the accompanying mushrooms and puffballs. Buried stumps and logs result in depressions as the wood decays. Although it is common practice when clearing large sites to bury tree stumps and large branches and roots, it creates problems for the turf manager for years to come.
The presence on the site of undesirable grasses and weeds can lead to serious weed problems for the turf manager. In a hybrid bermudagrass sports field, common bermudagrass would present problems for the turf manager. Bahiagrass, dallisgrass and other perennial grasses could also present problems for the turf manager since they cannot be selectively removed from some turfgrasses. Nutgrass, grassburs and other weeds present similar problems. These all need to be eliminated prior to planting the turfgrass.
The most effective, although most costly, method of weed control is sterilizing with methyl bromide, vapam or a similar product. These products, when properly applied, will effectively control most weeds and grasses. Critical planting sites such as sports fields and golf greens may require sterilization to eliminate these undesirable plants.
On areas outside of the playing field, nonselective herbicides such as glyphosate (Roundup) may be used to control weeds and grasses. However, plants must be actively growing at the time of application for these products to be effective.
Many annual weeds can be controlled by cultivating (disking or rototilling) the site immediately prior to planting. Other more difficult to control weeds may be controlled by repeated cultivations during dry conditions.
In general, preemerge herbicides should not be used prior to planting the site to a desirable turfgrass. These products may injure the newly planted grasses.
Cultivation. Construction sites for sports fields and golf courses often become compacted as a result of equipment operated on the site, deliveries to the site and cleanup operations after construction is complete. To alleviate compaction and to create more uniform and more favorable soil conditions, cultivation is necessary. Large sites can be cultivated with tractor-drawn equipment such as a chisel plow, subsoiler or disk plow; while small areas can be cultivated with a hand operated rototiller.
If the soil needs to be disturbed more than 4 inches deep, a chisel, disk or plow can be used. Use of a breaking plow or subsoiler will loosen the soil 6 to 12 inches deep. Such an operation will breakup a plow pan or clay pan several inches below the surface.
A plowed soil, or an undisturbed soil, can be further broken up with a disk and harrow. Disking a site in several directions will loosen the upper 4 inches and destroy most of the vegetation. Disking during summer months is most effective for vegetation control. Harrowing or dragging a chain or heavy mat will pulverize and smooth the soil surface after disking. All of these cultivation operations should be done when the soil is moist, but not wet. Cultivating wet soil destroys soil structure and produces large clods; whole dry soils become very hard and resist cultivation.
Small sites such as the infield of a baseball field or a golf tee can be effectively cultivated with a hand operated rototiller. By operating the rototiller in several directions, the upper 4 inches of soil can be pulverized and uniformly mixed. The rototiller is also used to incorporate organic material and soil amendments into the soil.
Soil Modification. Some sites would benefit from soil modification prior to planting grass. Extremely acid sites need limestone incorporated in the upper 4 to 6 inches at 2 to 4 tons per acre depending on soil test recommendations. Alkaline, high pH, sites may benefit from sulfur and/or gypsum. Most sites would benefit from organic matter incorporated in the upper 4 inches of soil.
In each case, the material to be incorporated can be spread on the surface and rototilled into the soil. Thorough mixing is essential to avoid leaving pockets of the amendment throughout the soil. It is possible to create a potting soil mixture with the existing soil, organic material and whatever amendments may be recommended. Flower beds and gardens often receive this type of preparation. However, turfgrass sites rarely receive the attention and expense of intensive soil modification. Sports fields and golf greens are the exception as they are intensively modified with sand, organic matter and other amendments.
Soil modification with amendments such as sulfur and limestone should be based on soil test recommendations. The use of organic materials will be based more on their availability and cost than on need. All soils, except some of the organic soils found in the southeast, would benefit from organic materials such as peat, compacted bark, sawdust or rice hulls. These organic materials improve soil aeration, increase nutrient content and promote microbial activity, all of which aid in the establishment of grasses.
Aggregate materials such as Turface, Greenschoice (SoilPro) and Isolite also improve the physical characteristics of soils. When incorporated at 10 to 15 percent (by volume) in the top 4 to 6 inches of the seedbed these materials increase aeration and drainage and reduce compaction. In sandy soils these aggregate materials also increase water and nutrient retention.
Grading. Drainage is the single most critical factor in the establishment and maintenance of turfgrasses. Grasses thrive on well-drained sites; but perish on poorly drained sites.
When developing a site, it is often necessary to "cut" high areas and "fill" low areas to establish the desired grade. This on-site contouring is referred to as "rough grading". Rough grading is usually done with a dozer on large sites or a tractor and blade on small sites. When rough grading a site, surface drainage must be uppermost in mind. Moving water away from playing surfaces, buildings, sidewalks, driveways, traffic areas, and other critical areas should be the main object of the rough grading operation.
If deep cuts are necessary on a site, steps need to be taken to replace some topsoil on the "cut" area. If large areas are excavated, the topsoil should be removed and stored separately from the subsoil. Then, as the site is being graded, the subsoil can be spread first and covered with the original topsoil.
If possible, avoid steep slopes on grass areas because establishment of grasses is difficult and soil erosion is likely. Gentle slopes, with water moving away from critical areas, are ideal on grassy sites. An ideal slope on grass areas is 1.0 to 2.0 percent with 0.5 percent slope being minimum. Where severe slopes cannot be avoided, construct retaining walls to limit the severity of the slope.
If topsoil is to be added to the site, grade stakes are needed following rough grading to establish a uniform depth of topsoil. At least 4 inches of topsoil are needed for grass areas and 6 to 8 inches would be desirable. When topsoil is in place and any necessary amendments are added the "finish grading" or "fine grading" needs to be done. Fine grading smooths and firms the topsoil in preparation for planting the site. Fine grading can be done by a box blade on small sites or a grader on larger sites. When the final contours are established, the site can be dragged with a heavy steel mat or chain drag to smooth the surface. Rolling may be necessary to firm the soil if there is not time to let rainfall settle the site. Final grading should be done after the site has been rolled or settled by rainfall or irrigation.
Grass SelectionSelecting the best adapted turfgrass for a site improves the quality of a sports field, golf course or lawns and reduces the cost of turf maintenance. Knowledge of the adaptation, use and maintenance requirements of turfgrasses is essential to selecting the best grass for a site.
People have identified certain plant species as being suited for turf since the needs first arose for close cropped playing fields. The original turf species were native grasses and legumes that survived close defoliation by grazing animals. Heavy use, frequent defoliation and the use of commercial fertilizers eliminated all but a few of the grasses for permanent turfs. And, increasingly frequent and close defoliation of turf areas narrowed the selection to about 25 species of grasses for turf use. Of those 25 species, only about 10 are used for turfgrasses in the Southern states.
Most turf species have been hybridized to produce varieties with specific turf characteristics. Fine texture, high density and dark green color were the first characteristics selected in turfgrasses. Later, insect and disease resistance, cold tolerance, salt tolerance and other special traits were developed. Today,grounds supervisors, golf course superintendents, and park managers have numerous turfgrass varieties from which to select a grass for a specific site.
In some situations, a mixture of grass varieties may best meet the requirements for a particular use or site.
To select a grass or grass mixture, the turf manager must have knowledge of environmental conditions, management and use relative to the site. Some grasses are suited to shade, others are not. Some grasses require supplemental watering to survive, others may not. And, some grasses tolerate traffic much better than others.
Selection Criteria. A wide range of environmental conditions occur in the southern states from semiarid western regions to high rainfall regions of the southeast and from transition climates in the central states to tropical regions in south Texas and south Florida. Most turfgrasses can survive in arid areas with supplemental watering. But, temperature limits the adaptation of several species. In the temperate climates of the northern states, cool season grasses such as bluegrass, bentgrass, ryegrass and fescue are grown. In the subtropical areas of the South, the warm season grasses such as bermudagrass, centipede, and St. Augustine grass are best adapted. In the transition zone between the temperate and subtropical climates, both cool and warm season grasses can be grown in some situations with good management.
Shade, or light intensity, is a major factor in the adaptation of a turfgrass. St. Augustine grass or tall fescue, for example, would perform well in an area receiving 50 percent of full sunlight. Bermudagrass would not be satisfactory under the same conditions. However, even the shade tolerant grasses require 30 to 40 percent sunlight to maintain a satisfactory turf.
Interactions between environmental conditions such as temperature and shade can also be important. Tall fescue, for example, may not perform well in the northeast in 50 percent shade, but in the transition zone, it might do well in partial shade. Likewise, temperature and moisture interact to influence the adaptability of a turfgrass. Bentgrass performs poorly on golf greens in the southeast because of the combination of high temperatures and high humidity. But, in the arid west where temperatures may be higher, bentgrass performs very well.
Soils also influence the adaptability of turfgrasses to a particular site. The sandy, acid soils of the southeast are well suited to carpetgrass, bahiagrass and centipedegrass. The heavy (clay or clay loam), alkaline soils of the west are best suited to bermudagrass and buffalograss. Some grasses such as ryegrass, bermudagrass and zoysia can be successfully grown on most soils.
Management practices often have an overriding influence on turfgrass selection. If a site cannot be watered, a drought tolerance grass such as bermudagrass or buffalograss is required. If a turf is not mowed more than twice a month, only the low maintenance grasses are suitable. In Tables 1 and 2, three levels of maintenance are described. A high level of maintenance implies frequent mowing, regular watering, several applications of fertilizer each year and a pest control program. In contrast, a low level of maintenance suggests no supplemental watering, monthly mowing, perhaps annual fertilization and no chemical pest control.
Turf use also influences the selection of grass varieties for specific sites. Some grasses such as the perennial ryegrasses and bermudagrasses tolerate heavy use. Others such as the bentgrasses and hybrid bermudagrasses tolerate close mowing for sports fields and golf greens. And, other grasses are best suited for roadsides, parks and school grounds because of rapid establishment and low maintenance requirements.
Selecting the best turfgrass for a site does not guarantee success. But, planting a grass not adapted to a site insures failure. An adapted turfgrass properly maintained will provide a beautiful and useful turf. Also, turf maintenance costs are less where adapted turfgrasses are used.
To select a turfgrass, use Tables 1-3 to identify grasses that meet all environmental conditions for a specific site. Then, review the descriptions for each grass meeting those requirements. Finally, select the variety that is best adapted in terms of environment and managements to that site.
Descriptions of Southern TurfgrassesCommon bermudagrass (Cynodon dactylon). Bermuda-grass was introduced into the United States in the 1700's from South Africa. It has since become naturalized throughout the southern states. Common bermudagrass is a medium textured warm season perennial species with a creeping growth habit. It spreads by rhizomes and stolons and can be established from seed. It grows rapidly during late spring and summer, remains green into late fall and goes dormant after a hard frost. Bermudagrass turns straw-colored during the dormant period and resumes growth when average daily temperatures are above 70°F for several days.
Common bermudagrass tolerates heavy traffic, moderate salinity and close mowing but has poor shade tolerance and is susceptible to winterkill at temperatures below 10°F. Common bermudagrass has a number of pest problems (leaf spot diseases, armyworms and white grub), but its rapid rate of recovery reduces the need for pesticides. It performs best under a moderate level of maintenance, but it can be used as a low maintenance grass in lawns, parks and along roadsides.
Improved common-type bermudagrasses that are planted from seed include Primavera, Sundevil, Sahara, Sonesta, Guymon and Cheyenne. These varieties are typically shorter growing and more dense than common bermudagrass.
Hybrid Bermudagrasses (Cynodon spp.). Most of the hybrid bermudagrasses have been developed in the last 25 years. Hybrid bermudagrasses produce a dense turf with a fine to medium texture and require a higher level of maintenance (fertilization, mowing and watering) than common bermudagrass. All must be established from sprigs or sod. The fine textured varieties including Tifway (419), Tifgreen (328), and Tifdwarf are best suited for sports fields and golf greens. Other varieties including Santa Ana, Sunturf, Ormond and Texturf-10 are best suited for lawns, fairways, and sports fields. Several hybrid bermudagrasses including Midiron and Tufcote have superior cold tolerance and are suited to the transition zone of the United States.
St. Augustine grass (Stenotaphrum secondatum). St. Augustine grass, often called carpetgrass, is native to the southern Atlantic and Gulf Coast states. It is a coarse textured, warm season perennial grass that spreads by large creeping stolons. It is largely propagated from sod or sod plugs although it can be established from sprigs. St. Augustine grass is limited to areas with mild winter temperatures. It is the most shade tolerant of the warm season grasses and has good fall color retention. St. Augustine grass is among the first of the warm season grasses to green up in the spring.
St. Augustine grass requires a moderate level of maintenance. It has a number of serious pest problems including brownpatch, chinch bugs, white grub and St. Augustine Decline. Several varieties of St. Augustine grass are available including Bitter Blue, Delmar, FX-10, Seville, Texas Common, Floratam, Floralawn and Raleigh. Floratam and Floralawn, Seville and Raleigh are resistant to St. Augustine Decline, but only FX-10, Floratam and Floralawn are also resistant to chinch bugs. However, these later varieties are very coarse textured and are not as shade tolerant or cold tolerant as other varieties.
Zoysiagrass (Zoysia spp.). Zoysiagrass was introduced into the United States from Southeast Asia in 1911. It is a warm season perennial that forms a very dense turf that is highly resistant to wear. It spreads by stolons and rhizomes. The texture of zoysiagrass ranges from very fine (Z. tenuifolia) to fine (Z. matrella) to coarse (Z. japonica). Leaf blades of zoysiagrasses are much stiffer than those of other grasses. The improved zoysiagrasses must be established from sprigs or sod. Zoysiagrass turns brown after the first hard frost, but recovers as the temperatures reach 70°F in the spring. Zoysiagrass has moderate shade tolerance, good drought tolerance and excellent wear tolerance.
The major varieties of zoysiagrass for turf use are Meyer and Emerald. Meyer is a medium textured variety of Z. japonica used for lawns. Emerald is a fine textured hybrid between Z. japonica and Z. tenuifolia used primarily for lawns and golf courses. Z. tenuifolia is a very fine textured variety used primarily as a ground cover for difficult to mow areas of a landscape. Z. tenuifolia is not as cold tolerant as the other varieties of zoysiagrass.
Several seeded varieties of Z. japonica are commercially available. These grasses are more coarse and less dense than Meyer or Emerald zoysiagrass.
Centipedegrass (Eremochloa ophiuroides). Centipede-grass is a native to China and Southeast Asia. It was introduced into the United States in 1916 and has become widely grown in the southeastern states. It is a warm season perennial that spreads by stolons and is readily propagated from seed. Centipedegrass is best adapted to sandy, acid soils and develops severe iron chlorosis on alkaline soils. Centipedegrass is a coarse textured, low maintenance turfgrass ideally suited for lawns. It requires less mowing than bermuda or St. Augustine grasses and is often called "lazy man's grass." It produces rather short, upright stolons resembling a centipede - thus, the name, centipedegrass.
Centipedegrass forms a dense, coarse textured turf. It turns brown after a hard frost, but recovers whenever temperatures are above 70°F for several days. Centipedegrass is moderately shade tolerant and slightly more cold tolerant than St. Augustine grass.
Several selections of centipedegrass have been made, but none have found prominent use in turf. Oklawn centipedegrass was developed by Oklahoma State University as a superior drought tolerant and cold tolerant variety. The University of Tennessee developed Tennessee Hardy as a variety with superior cold tolerance. Neither of these varieties are commercially available today. Auburn University released AU Centennial Centipedegrass in 1983 as a dwarf variety with good turf characteristics. It is presently available through sod growers in several southern states. Common centipedegrass produced from the seed of early introductions remains the most readily available variety.
Buffalograss (Buchloe dactyloides). Buffalograss is a native warm season perennial grass widely used for turf in western regions of the United States. It spreads by creeping stolons and is propagated from seed or sod. Buffalograss is one of the few grass species having separate male and female plants with the female plants producing a bur containing the seed.
Buffalograss is not shade tolerant and has poor wear tolerance, but has excellent cold and drought resistance. Although it develops a dry, straw-colored appearance during prolonged dry periods, it recovers rapidly after rainfall or irrigation. Buffalograss requires little mowing and is well suited to low maintenance situations such as lawns, parks and roadsides.
"Prairie" and "609" buffalograsses are improved types that must be propagated from sod. Both varieties are female selections with greater density than common types. Common types include Texoka, Commanche, Plains and Topgun
Carpetgrass (Axonopus affinis). Carpetgrass is a warm season perennial grass introduced into the United States from the West Indies in the early 1800's. Carpetgrass spreads by creeping, laterally compressed stolons. It is often confused with St. Augustine grass. In contrast to St. Augustine grass, carpetgrass has blunt, rounded leaf tips. Also, the leaf blade makes a 45° angle with the sheath; whereas, the blades of St. Augustine grass emerge at a 90° angle from the sheath. In addition, the seedstalks of carpetgrass are 8 to 10 inches tall and forked; whereas, the seedstalks of St. Augustine grass form a flattened corky stem with the seed embedded on one side of the seedhead.
Carpetgrass is adapted to wet, poorly drained soils in the southeastern states. It grows well with little or no fertilization and has very few pest problems. It is more shade tolerant than bermudagrass, but less than St. Augustine grass. Carpetgrass can be easily established from seed. Carpetgrass does not produce a thick, dark green turf like St. Augustine grass. Carpetgrass produces numerous tall seedstalks throughout the summer that require weekly mowing to maintain a neat appearance.
Bahiagrass (Paspalum notatum). Bahiagrass was introduced into the United States from Brazil in 1914 by the USDA. It is a warm season perennial species that is well adapted to sandy soils in the southeastern states. It is readily established from seed or sod and spreads by short, stout rhizomes. Bahiagrass forms a rather open sod and has a coarse texture. The principle disadvantage of bahiagrass for turf is its prolific production of tall seedheads from May through November. Weekly mowing is required to maintain a neat appearance.
Bahiagrass is moderately shade tolerant and performs quite well under low maintenance conditions. It is especially well suited for roadsides, utility rights-of-way, parks and other low maintenance sites. Varieties of bahiagrass include Pensacola, Argentine and Paraquayan.
Tall fescue (Festuca arundinacea). Tall fescue is a cool season perennial bunch grass. Like all of the cool season turfgrasses, tall fescue was introduced into the United States from Europe during the Colonial Period. In thin stands, individual plants develop a rather broad crown through abundant tillering. Occasionally, plants develop a few short, thick rhizomes. Tall fescue is coarse textured, shade tolerant and moderately drought resistant.
Tall fescue is adapted to a wide range of soil and climatic conditions. Although it can be grown in the southern region, it is best adapted to the transition and temperate zones of the United States. It performs well under low maintenance conditions. Adventure, Falcon, Houndog, Olympic and Rebel are some of the varieties suited for turf use. All varieties are established from seed.
Perennial ryegrass (Lolium perenne). Perennial ryegrass is a cool season bunch grass that behaves as an annual, short-lived perennial or perennial depending on environmental conditions. It forms a fine textured, dense turf and is characterized by rapid germination and fast growth during the seedling stage. In the southern coastal states, ryegrass behaves as an annual. On lawns, golf courses and athletic fields, perennial ryegrass is used to provide a fast cover and increased wear resistance. Perennial ryegrass is established primarily from seed. Varieties include Pennfine, Prelude, Manhatten, Birdie, Regal, Fiesta, Diplomat, Derby, Yorktown, Citation, Caravelle and others.
Creeping bentgrass (Agrostis palustris). A cool season perennial that spreads by creeping stolons. Creeping bentgrass forms a very fine textured turf and is primarily used for golf and bowling greens. It is best adapted to temperate climates in northern states and to high altitude regions in the southern and western states. Bentgrass is used on golf greens in the transition zone, but only on modified soils and under a high level of maintenance.
Seeded varieties of creeping bentgrass include Cobra, SR1020, Cato, Crenshaw, Seaside, Penncross, Emerald, Pennlinks and Penneagle. Vegetative strains include Cohansey (C-7), Toronto (C-15), Congressional (C-19) and Washington (C-50).
Seashore paspalum (Paspalum vaginatum). A perennial warm season grass native to tropical and subtropical regions of North and South America. Seashore paspalum is slightly more coarse than common bermudagrass and spreads by rhizomes and stolons. Its outstanding characteristic is its tolerance to poorly drained sites and saline conditions. Along the Texas coast it is found growing into brackish ponds and estuaries.
The grass produces fine turf when mowed at heights of 1 inch or less. Above a 2 inch height the grass becomes thin and unsightly. Varieties include "Futurf" and "Adalayed" (also called "Excalibre"). Seashore paspalum must be propagated from sprigs or sod.
PlantingGrasses are established from seed or vegetative material (sprigs or sod) depending on the grass variety selected and the time available to develop a cover. The type of planting material to be used, the method of planting, the quantity of planting material needed and the best time of year to plant each of the grass species used in the South are shown in Table 4.
Seeding. Southern turfgrasses that can be established from seed include common bermudagrass, centipedegrass, carpetgrass, bahiagrass, buffalograss and all of the cool season grasses. St. Augustine grass, zoysia and the hybrid bermudagrasses are established from vegetative planting rock. When establishing grass from seed, seed quality, seeding rate, seeding date and seeding method must be considered.
All packages or bags of seed are labeled with information on the variety, purity and germination percentage of the seed. This information is vital when determining the cost and seeding rate for a particular grass. Both cost and seeding rate need to be determined on some standard basis, and for grass seed, the basis for comparison is percent "pure live seed" or percent "PLS". Percent PLS is calculated by multiplying the percent purity by the percent germination. For example, a 50 pound bag of common bermudagrass seed with a percent purity of 97 and a percent germination of 90 contains 43.65 pounds of "pure live seed" (0.97x0.90x50). When comparing seed cost, make the comparison on the basis of PLS. The cheapest bag of seed may be the most expensive on the basis of PLS. Seeding recommendations are also made on a PLS basis.
Another reason to review the label is to determine the "weed seed" or "crop seed" that may be present. In cool season grasses, weed seed can present serious problems for turf managers. For example, annual bluegrass seed in bentgrass creates weed problems for the golf course superintendent from the start. Likewise, crabgrass seed in bermudagrass would be undesirable. The cost of seed increases as more of the "weed" and "other crop" seeds are removed from a lot of grass seed. Since it would be too expensive to remove all "weed" or "other crop" seed from a lot of grass seed, the buyer should purchase the "cleanest" seed he can find for critical sites. For low maintenance sites, the less expensive seed may be planted.
Additional information found on the label includes the date of the germination test. If the germination test is more than one year old, the information may not be valid. Generally, germination percentage decreases with time.
Seeding rates depend on grass species, the purpose for the turfgrass and the time available to develop a cover. Grasses with a creeping type growth habit are generally seeded at lower rates than bunch-type grasses. Although seeding rates are expressed in terms of pounds per unit area, the number of seed per unit area is more important. Table 5 provides information on seed counts and seed densities at recommended seeding rates. In the case of centipedegrass and buffalograss seed densities as low as 1 seed per sq. in. are recommended; whereas, for all other grasses at least 7 to 10 seed per sq. in. are recommended. This discrepancy is the result of the cost of buffalograss and centipedegrass seed compared to the other grasses. Even at such low seeding densities, buffalograss and centipedegrass seed cost more per unit area than all of the other grasses. In the case of buffalograss and centipedegrass, seeding rates are based more on cost rather than on desired seed densities.
Seedling vigor, dormancy and seeding survival also need to be considered when deciding on seeding rates. Bermudagrass, buffalograss, ryegrass and tall fescue seed all possess good seedling vigor. Thus, seedlings of these grasses could be expected to establish very fast. Bahiagrass, centipedegrass and bentgrass have low seedling vigor and require much longer to establish a complete cover. However, in the case of centipedegrass, seed cost prevents increasing the seeding rate to compensate for low seedling vigor.
Another factor, seed dormancy, also influences the seeding rate of some grasses. Bahiagrass and buffalograss seed have a high percentage of dormant seed, 40% or more. In the case of bahiagrass, increasing the seeding rate compensates for the dormant seed. But, buffalograss seed is too expensive to increase the rate. Therefore, buffalograss seed are generally treated to break dormancy and increase seed germination to 80% or more.
Seedling survival, a function of environmental conditions and management practices during the germination period, also influences seeding rates. Any factor that increases the time required for germination or the time the grass is in the seedling stage, also increases seedling losses. Extremely high or low soil temperatures, droughty or excessively wet soils, low soil fertility, seed improperly planted (covered too deep, left uncovered on the surface or nonuniform distribution), excessive seedling densities and the presence of some preemergence herbicides all increase seedling losses. Thorough seedbed preparation, proper planting techniques, correct planting date and proper post planting care all reduce seedling losses.
Date of planting is critical when establishing grass from seed. Soil temperature and the expected duration of favorable soil temperatures are the primary considerations for selecting the planting date. Cool season grasses should be planted in the fall when soil temperatures are 72°F and several months of favorable growing conditions remain. Seed germinates rapidly and seedlings can grow vigorously for the first several months in the fall. If cool season grasses are planted too early, high soil temperatures create stressful conditions during the seedling stage and result in high seedling losses. Weeds also compete with grass seedlings for a long period if seed are planted too early.
Planting cool season grasses too late results in immature plants going into the winter months and high seedling losses can occur. Even though soil temperatures may be favorable at the time of planting, the duration of favorable temperatures may not be adequate to develop mature plants and a hard freeze can result in high seedling losses.
In the South, the fall planting dates are best for cool season grasses. But, successful plantings can be made in the spring where cool temperatures are likely through May. In most areas of the South, high springtime temperatures result in high seedling losses. Weed populations are also greater in the spring and many weeds compete with the turfgrass all summer.
Late spring and early summer are ideal seeding dates for warm season grasses. Soil temperatures are favorable by late spring and a long growing season is ahead for the warm season grasses. Late summer is another favorable date for seeding warm grasses since soil temperatures are favorable and extreme air temperatures are abating.
Spring seeding dates should be delayed for warm season grasses until soil temperatures are above 65°F. Weeds often grow faster in the early spring than the grasses if planting occurs too early. Thus, seedling losses can be high due to competition with weeds.
Late fall plantings of warm season gasses should generally be avoided because seedlings do not have time to mature prior to winter. However, grasses such as bahiagrass and buffalograss that have a high percentage of dormant seed, can be seeded in late fall with the expectation of significant germination the following spring.
Seeding methods have a tremendous influence on the successful establishment of grasses. Ideally, grass seed should be uniformly distributed at recommended seeding rates, covered with -inch of topsoil and rolled to firm the seedbed. Grass drills, or planters, are made to perform all of these tasks in a single pass over the site. The Brillion grass seeder is an example of such a planter that works well for small seeded grasses such as bermudagrass.
Other options include broadcasting the seed uniformly over the surface and covering seed with straw or mulch. The hydroseeder works well for this type of seeding operation. Grass seed, fertilizer and mulch can be broadcast over the site through a high pressure nozzle with water. Hydroseeding was developed for planting sites that were difficult to reach with conventional equipment. Steep slopes, rocky slopes, reclamation sites and other inaccessible areas were well suited to hydroseeding. Since its development the hydroseeder has found much broader use in grass establishment and is used today for seeding lawns, golf courses, sports fields and other sites.
On small sites, seed can be broadcast with a hand seeder or fertilizer distributor over the surface of a lightly raked seedbed. After seeding, firm the soil with a roller and lightly water the site. If watering is limited to light, frequent applications, this method works well. But, excessive watering will wash the seed and result in a nonuniform stand of grass seedlings.
Sprigging. All of the bermudagrasses, the zoysiagrasses and seashore paspalum are readily established by sprigging. St. Augustine grass and centipedegrass can also be established from sprigs, but the risks are greater. For large plantings such as golf courses and sports fields, sprigging provides the most practical method of establishment.
A grass sprig consists of a stem or rhizome segment with at least one node or crown (multiple nodes) and any leaves and roots that might be attached to the node. Usually, 3 or more nodes are found on a single sprig.
Sprigs are harvested by shredding sod, by rototilling sod and raking, by vericutting or by a sprig harvester. Sprigs consisting of rhizomes, crowns and only a few green leaves are most desirable. Such sprigs will transport and store much better than green, leafy sprigs. Rhizomes are also more drought tolerant and will survive several days without water; whereas, a green leafy sprig without a crown or rhizome segment may die within hours if not kept moist after planting.
Bermudagrass, zoysiagrass and seashore paspalum are the only vegetative propagated warm season grasses with rhizomes. Thus, those grasses are best suited to sprigging. St. Augustine grass, centipedegrass and buffalograss sprigs that consist only of stolons are much more susceptible to drought stress after planting. Such sprigs are also more likely to overheat and deteriorate during shipment. Sprigs that appear moldy when they arrive at the planting site should not be planted. Such sprigs desiccate rapidly after planting and replanting is often required.
The quality of sprigs, like that of seeds, is critical to successful establishment. Just as weed seeds are undesirable in a lot of grass seed, off-type grasses are undesirable in a bushel of sprigs. Common bermudagrass sprigs can cause serious problems in a bushel of hybrid bermudagrass sprigs. Likewise, bermudagrass sprigs in zoysiagrass or other turfgrasses lead to serious weed problems for the turf manager.
In addition to purity, sprig vigor is another aspect of sprig quality. Sprigs harvested by digging are usually the most vigorous since they include rhizomes, crowns and the large stolons found near the soil surface. Such sprigs are more vigorous than the leafy sprigs harvested above the soil level. The more vigorous sprigs tolerate stress and develop a root system more rapidly than the less vigorous sprigs. Consequently, sprig survival is much greater for the more vigorous sprigs.
Sprigging rates depend on grass varieties, planting method, sprig quality and the time available for a complete cover. Bermudagrass sprigs spread faster than all other grasses and can be planted at lower rates. Large sites such as golf course fairways and sports fields can be sprigged at 250 to 300 bushels per acre with an expected cover in 10 to 12 weeks. Where a faster cover is needed sprigs can be planted at 10 to 25 bushels per 1,000 sq. ft. Golf greens sprigged at 25 bushels per 1,000 sq. ft. can be in play in 4 to 6 weeks.
Planting method also influences sprigging rates. Most sprigs are broadcast over the site with a distributor or hydroseeder at rather high rates of sprigs. However, row planters are available for sprigging that use much less planting material. If the row planter functions properly, it places the sprig in a narrow furrow, covering 50 to 80% of the sprig with soil. If water is applied immediately (within 30 minutes), a very high percentage of sprigs survive. In contrast, broadcasting sprigs over the surface and depending on an irrigation system to keep them moist results in high sprig losses. Covering broadcast sprigs with a mulch helps to reduce their losses.
Sprigging rates can also be reduced by planting high quality sprigs. Sprigs harvested by digging are more vigorous and have a higher survival rate; thus, lower rates of planting can be used. Where only the "tops" of bermudagrass are planted, twice the quantity of planting stock may be needed as when dug sprigs are used.
Finally, the time available to develop a complete cover will significantly influence planting rates. The higher the rate of sprigging, the faster a cover will develop. However, the cost of sprigging also increases with each increase in planting material. By sprigging 5 bushels of bermudagrass sprigs per 1,000 sq. ft., a satisfactory cover can be developed in 3 to 4 months. At 10 bushels, a complete cover can develop in 2 months; and at 25 bushels, in 1 month. The cost of planting material for those rates may range from $20 to $100 per 1,000 sq. ft., or from $500 per acre to $2,500 per acre. Sometimes, however, the need to use a facility by a certain date precludes the use of the lower planting rates. On critical areas, such as sports fields and golf greens, the higher planting rates should be used.
Plugging. Plugging refers to the setting out of small sod blocks or plugs (2 to 4 inches in diameter), on 6-, 12- or 18-inch centers to establish a turfgrass. The plugs need to be rolled so that the soil on the sod block, or plug, is level with the soil surface. Rooted plugs are available which have been grown in about 2 inches of soil or organic matter. When rooted plugs are planted, a hole about 2-inches deep should be dug. Do not simply place the plug on the soil surface.
St. Augustine, zoysia and centipede grasses are frequently established from plugs. St. Augustine grass plugs spaced on 18-inch centers will cover the site in about 2 months. Centipede and zoysia grasses need to be plugged on 6- to 12-inch centers to cover in one growing season.
Although plugging requires less planting material than sodding, the labor requirement for plugging is greater than that for sodding. Rooted plugs, however, require less attention after planting than sod since their root system was developed prior to planting.
Sodding. Sodding is the laying of blocks or rolls of sod directly over a prepared seedbed to provide an instant lawn. Solid sodding obviously requires more planting materials than other methods, but it eliminates many of the problems associated with seeding, sprigging or plugging.
When sodding a site, lay sod blocks or sod rolls like bricks on a smooth surface that has been firmed by rolling or settled by rainfall or irrigation. The seedbed needs to be moist, but not wet, at the time sod is laid. After the sod is laid, roll it lightly to eliminate air pockets and firm contact with the soil.
In addition to avoiding many problems with other methods of establishment, sodding can be done any time of the year provided irrigation is available at the site.
A frequent mistake on commercial sites is poor seedbed preparation prior to sodding. Although sod will cover up a lot of problems, the turf manager is left to deal with them. All of the steps of good seedbed preparation should be followed prior to sodding a site.
Care After EstablishmentWater newly planted turf areas regularly. Water lightly and frequently to prevent the surface from drying. As the young seedlings develop or as the sprigs or sod begin to take root and spread, reduce the frequency of watering and increase the amount of water applied per watering. This permits the development of a deep root system and ultimately reduces the amount of water needed.
The time to mow will depend on the species planted. Mow newly planted areas as soon as the grass is 1° to 2 inches high. Mow frequently enough to prevent removing more than half of the growth at any one mowing.
Fertilize newly seeded or sprigged turfgrasses once a month with a complete fertilizer at a rate equivalent to 1 pound of nitrogen per 1,000 sq. ft. Follow soil test recommendations, but in the absence of this information a complete fertilizer should be used. On sandy textured soils, supplement the complete fertilizer with an additional pound of nitrogen between applications of the complete fertilizer. Water after each application of fertilizer.