Managing Lawns and Turfgrass
Brad Fresenburg and Lee Miller
Division of Plant Sciences
It takes some time and effort to develop a lawn with the right mixture of turfgrass species and varieties for your landscape and situation, but it is worth the investment to achieve results that are attractive, durable and easy to maintain. Important questions to ask are: How will the area be used, and what level of maintenance will it receive? What are your expectations for your yard? What are the different levels of shade in your landscape? What are your climate and soils?
Managing a lawn involves decisions about frequency of mowing, fertilization and watering, and whether you plan to use crabgrass preventers or products to control turfgrass diseases and insects. You will also want to evaluate any historical information you have about disease and insect occurrences. Taking time to consider these factors in advance will help you select the best species or mixture of species for your situation.
The key to a quality lawn is to select turfgrass species and varieties that will grow best in your region. Finding those varieties that will offer good quality, color, density and disease resistance will make lawn care easier.
The following information on available turfgrass species and varieties will help you select species well adapted for specific situations. There are hundreds of commercially available varieties for most turfgrass species, but not all will ever be available for sale by any single seed company, garden center or nursery. Local seed companies align themselves with specific national seed growers, which limits the number of varieties they sell.
In addition to providing many of the premium seed varieties, seed suppliers can provide useful information for selecting species and varieties that perform best in particular situations. Many of the major seed companies have their own websites that offer information and list contacts and retail sources where you can buy their products. Websites will often sell small quantities, which they will deliver directly to your door, a convenience to consider.
The difficulty can be finding the varieties you read about. One approach to selecting varieties is to list those recommended for your area or with the desired characteristics and then cross-reference your list to the varieties you find available.
Before you buy, read the information on the seed label to make sure you know what you are buying (Figure 1).
Figure 1 Seed labels
Seed bags carry a printed tag with important information, including species, variety name, purity, germination, weed seed and noxious weed seed content, and testing date. The species and variety names can be cross-referenced to local recommendations of those that grow best in your area. As long as purity and germination are acceptable, the next vital information is the weed list. The best products will have 0 percent listed for weeds and noxious weeds. Avoid products with large amounts (greater than 0.2 percent) of annual bluegrass (Poa annua) and rough bluegrass (Poa trivialis); patches of these weeds will decline during the summer, creating unsightly spots in your lawn.
Turfgrass species can be identified by various plant parts. The primary plant parts used in identification are the leaf blade, leaf tips, collars, ligules, auricles and roots (Figure 2). Knowing the various shapes and sizes of different species and the characteristic presence or absence of key plant parts will help you to identify turfgrass species.
First it is necessary to distinguish between cool-season and warm-season grasses. Plants that have rhizomes (below-soil surface runners) or stolons (surface runners) are warm-season plants. Some cool-season plants (many bluegrasses, a few turf-type fescues) have small rhizomes, but none have stolons. Once a plant is known as a cool-season or warm-season species, further identification can be made.
Cool-season species are characterized as C3 plants, which means the first product of the photosynthesis process is a compound containing three carbon atoms. Cool-season grasses grow best in the spring and fall when air temperatures range between 60 and 75 degrees F. The best root growth occurs when soil temperatures range between 50 and 65 degrees F. The growing season for cool-season grasses ranges between the months of March and November; however, these grasses do not grow well in the hot summer months. The cool-season grasses include turf-type tall fescue, Kentucky bluegrass, perennial ryegrass, fine fescue and bentgrass. Bentgrasses are used in high-maintenance golf courses and will not be discussed here.
Within this turf management region, neither warm- nor cool-season grass species are completely adapted — from Turf Management in the Transition Zone by John Dunn and Kenneth Diesburg.
Turf-type tall fescue (Festuca arundinacea Shreb.)
- Suggested seeding rate: 7 to 9 lbs. per 1,000 sq. ft.
- Mowing height: 3 to 4 inches
- 1 to 2 mowings per week
Tall fescue has been a favorite for nonirrigated turfgrass in the Transition Zone (Figure 3) since the release of Kentucky 31 in 1943. Tall fescue forms a deep root system in sandy soil or clay and tolerates a wide range of soil pH. It grows well in moderate shade and in open, sunny locations. The species tolerates summer heat and drought better than any other cool-season grass.
Some turf managers prefer to mix tall fescue with Kentucky bluegrass. Such mixtures of two or more compatible species often produce a better-quality turf than a single species because one of the species will be more resistant to prevailing diseases or other stresses that come over time. For example, research has shown that in some years, diseases such as Rhizoctonia brown patch infects tall fescue without affecting Kentucky bluegrass. At other times, dollar spot severely affects Kentucky bluegrass while tall fescue is resistant.
To mix species, a blend of two or three improved tall fescues combined with a blend of two or three Kentucky bluegrasses is suggested. Use a ratio of 9-to-1 fescue to bluegrass blend by seed volume. Avoid using the more aggressive Kentucky bluegrass cultivars, which may be too competitive with tall fescue.
Seed distributors often sell turf-type tall fescue blends that combine several different tall fescue cultivars. These blends are ideal for home lawn use and are generally less expensive than buying single varieties.
Use of the forage-type tall fescues is not recommended, as this type of tall fescue, although persistent, results in lower lawn quality than turf-type cultivars. Its use should be restricted to roadsides and other low-profile turf sites. If used, the seeding rate should be increased to 10 pounds of seed per 1,000 square feet.
A milestone in the development of tall fescue occurred with the release of Rebel tall fescue in 1979. Rebel's leaf texture was finer, about two-thirds the width of a Kentucky 31 tall fescue leaf. Rebel also spreads more aggressively when producing tillers, which means that only one-third to one-half as much seed is needed to establish turf.
In recent years, numerous turf-type tall fescues have appeared on the commercial seed market. Some are so-called dwarf varieties, with a slower vertical growth rate than other turf-type tall fescue cultivars. Dwarfs often require fewer mowings than some of the other tall fescue cultivars, but they may also be slower to recover from disease and injury.
The availability of many new tall fescue cultivars provides fresh options for cool-season turf in the Transition Zone. Several of these varieties offer resistance to some of the common turf diseases, especially brown patch. Therefore, selecting the more resistant varieties will improve turf quality. The new varieties generally will still require fungicides for the control of brown patch.
Turf-type tall fescues can appear a deep emerald green with a slightly coarser texture than bluegrasses. The sheath of the plant at the crown appears pinkish. Tall fescues can appear clumpy and have severe thinning. The leaves have a rolled vernation with expanded leaves showing prominent evenly spaced veins and rough leaf edges. The sheath is round, smooth and split. Ligules are blunt or absent and may have hairs on the margins. Auricles are indistinct and blunt.
Kentucky bluegrass (Poa pratensis L.)
- Suggested seeding rate: 2 to 3 lbs. per 1,000 sq. ft.
- Mowing height: 2.5 to 3.5 inches
- 1 to 2 mowings per week
Kentucky bluegrass is well adapted to a moderate climate with average daily summer temperatures below 90 degrees F, soil pH of 6.0 to 7.0, and adequate moisture. Bluegrasses are less drought tolerant than tall fescue. They become increasingly difficult to maintain as summer temperatures approach and exceed 90 degrees F. Careful irrigation is required to maintain quality Kentucky bluegrass turf in hot, dry summers. For these reasons, as recommended in the previous section, mixtures of bluegrass with other grasses such as turf-type tall fescues (10 percent bluegrass, 90 percent fescue) combine the advantages of each species to mask their respective weaknesses.
As a group, the Kentucky bluegrasses adapt best to open, sunny areas in fall and spring. During hot summers, bluegrass often does best in areas that receive afternoon shade. Turfgrass breeders have managed to incorporate a moderate degree of shade tolerance in several newer cultivars, partly because these have improved resistance to powdery mildew.
Unfortunately, most common Kentucky bluegrass types are weakened at some point by unfavorable environmental conditions or diseases such as leaf spot. However, turfgrass breeding programs have developed improved cultivars, such as Merion, named for the Philadelphia golf course where it was discovered. Merion was a big improvement over common Kentucky bluegrass, but in spite of its resistance to leaf spot disease, it is still highly susceptible to other diseases, such as stripe smut and summer patch.
Other bluegrass cultivars, such as Flyking and Pennstar offered further improvements, but vulnerability to summer diseases still discouraged their use in the Transition Zone, especially for high-traffic areas and closely mowed golf course fairways, tees and sports fields. Newer cultivars have good resistance to brown patch disease, but they are still susceptible to dollar spot, leaf spot and summer patch, so selecting bluegrass varieties that offer some resistance to these diseases is a practical first step in lawn establishment.
Blends of Kentucky bluegrasses look rich with dark, blue-green colors that make them visually pleasing. Bluegrasses do develop tillers and small rhizomes, which allow bluegrasses to recover better than tall fescues from thinning or other problems. The leaves have a folded vernation, which is smooth on top with a translucent midvein. The leaf tips are boat-shaped and look much like the end of a canoe. The collars are considered medium in height, and the auricles are absent. The ligule is short and blunt. The sheath is round, smooth and split.
Perennial ryegrass (Lolium perenne L.)
- Suggested seeding rate: 6 to 8 lbs. per 1,000 sq. ft.
- Should not be seeded alone
- Mowing height: 2.5 to 3.5 inches
- 1 to 2 mowings per week
Unfortunately, many seed mixtures and blends available to homeowners at local garden centers contain large amounts of ryegrass (both annual and perennial). Though ryegrasses tend to germinate quickly, which can help them establish quickly, they are also susceptible to disease and generally have not been tolerant of high summer temperatures. Current breeding work, using germplasm from southern states, should lead to new cultivars with better summer qualities than those currently available, but until this happens, the best use of perennial ryegrass in the Transition Zone is for sports fields where rapid establishment is needed and funds are available for periodic fungicide use.
Perennial ryegrasses have not been popular in the Transition Zone, where extreme summer temperatures and humidity create an ideal environment for Rhizoctonia brown patch, dollar spot and other warm-weather diseases. Manhattan, Pennfine and several succeeding ryegrass cultivars showed better disease resistance than common types, which usually decline after one or two summers until little remains of the original turf. New generations of perennial ryegrass also offer improved heat tolerance. Most of these ryegrasses are deep-rooted and will recover rapidly from drought stress when soil moisture is replenished and temperatures are moderate.
Manhattan and Pennfine and other ryegrasses have been widely used in seed mixtures with Kentucky bluegrass and other cool-season grasses because of their quick germination and other qualities mentioned earlier. Athletic field managers depend on them for rapid germination (five to 10 days) to fill worn areas in turf cover after games. In lawns, they persist better than most Kentucky bluegrasses on wet, lower pH, infertile soils.
Manhattan-type perennial ryegrasses are characterized by tough leaf tissue consisting of thick-walled cells that helps the ryegrass tolerate traffic but also makes it tougher to mow. A sharp mower is needed for perennial ryegrass turf to prevent fraying of leaf tips that produces an unsightly brown cast. Pennfine-type perennial ryegrasses have somewhat softer leaves that are easier to mow.
Perennial ryegrasses have deep emerald colors that are attractive, particularly in the spring and fall. Leaf blades have a folded vernation that appears fine in texture and tapers to a sharp point. The backsides of the leaf blades are glossy, which can lead to a distinct striping effect as sometimes noticed on athletic fields. Collars are distinct and divided. Auricles are small and clawlike. Ligules are small membranous, blunted to pointed structures. The sheath is usually compressed and smooth and appears reddish at the base of plants. Perennial ryegrasses do not produce rhizomes.
Fine leaf fescue (Festuca spp.)
- Suggested seeding rate: 5 lbs. per 1,000 sq. ft.
- Should not be seeded alone
- Mowing height: 3 to 4 inches
- 1 mowing per week
Fine leaf fescues are often used in lawn seed mixtures with Kentucky bluegrass or ryegrasses. Rapid germination allows them to provide early cover that prevents soil erosion and retards weed competition, while Kentucky bluegrass develops at a slower pace. Fine fescues grow best in dry, shady lawn areas that have slightly acid soils, conditions that discourage growth of Kentucky bluegrass. Proper management of fine leaf fescues in a shady environment includes high mowing with little fertilizer and water.
When irrigated, fine leaf fescues will adapt to open, sunny areas in mild coastal climates and to dry southwestern climates. They will not persist in areas where warm, humid summers provide optimal conditions for diseases such as leaf spot, dollar spot, brown patch and summer patch.
Fine leaf fescues have pointed and bristle-like leaf blades that are dark green. Collars are usually narrow, but are broad in Chewings. Auricles are absent. Ligules are membranous and short. The sheaths are usually round, but are flattened in Chewings.
The primary species of fine leaf fescues used for turf are briefly described below.
Chewings fescue is one of the quickest of the fine fescues to establish turf. Its aggressiveness makes it a better companion grass for perennial ryegrass than for Kentucky bluegrass. It adapts to closer mowing than other fine fescues. This grass is moderately susceptible to dollar spot but has better resistance to red thread than other fine leaf fescues.
Slender creeping red fescue spreads by short, fine rhizomes. This fescue establishes rapidly to produce a dense turf but is highly susceptible to red thread disease.
Strong spreading, creeping red fescue produces rhizomes that are coarser than those of the other fine spreading fescues, which may aid in drought tolerance. Leaf texture is somewhat coarser than that of other fine fescues. Spreading fescue is similar in color and compatible in seed mixtures with Kentucky bluegrass. Disadvantages of spreading fescue include intolerance of close mowing and a high susceptibility to disease in warm, humid summers.
Hard fescue adapts to shaded areas but is also adapted to sunny, hot, dry locations with infertile soils. Hard fescues have slower establishment and leaf growth and better tolerance to summer stress than other fine fescues, with Chewings fescue being the second most tolerant. Hard fescue's tolerance of dollar spot and red thread disease is generally best among the fine fescues.
Sheep fescue has a lower rate of vertical growth than either Chewings or hard fescue. Sheep fescue has good tolerance of cold and drought. Some new cultivars have good resistance to red thread and dollar spot.
Warm-season species are characterized as C4 plants, with the first product of the photosynthesis process being a compound that contains four carbon atoms. Warm-season grasses grow best in the summer, from May through September, when air temperatures range from 80 to 95 degrees F. Best root growth occurs when soil root temperatures are from 75 to 85 degrees F.
Zoysiagrass (Zoysia japonica L.)
- Suggested seeding rate: 1 to 2 lbs. per 1,000 sq. ft. in late May to late June
- Suggested sprigging rate: 8 to 10 bushels per 1,000 sq. ft. in late May to late June
- Suggested plugging rate: 2-inch plugs planted on 1-foot centers in late May to late June
- Mowing height: 1.5 to 2 inches, best at 1 inch
- Taller height, 1 mowing per week; short height, 2 mowings per week
Zoysia japonica originated in the western Pacific area. It is the species to which Meyer zoysiagrass belongs. Meyer has good heat and drought tolerance and is more winter hardy than bermudagrass, the other principal warm-season grass grown in the Midwest. Excellent summer qualities made Meyer a logical choice, in the 1960s, of golf course superintendents, who considered it a good alternative to Kentucky bluegrass for Transition Zone summers.
In addition to its good summer qualities, Meyer's tough leaf tissue is an added advantage for use on high-traffic areas such as golf course fairways and tees. Its mature turf is dense and tends to exclude most weeds. A high-quality lawn can be maintained with 1 to 2 pounds of nitrogen per 1,000 square feet per year. Research plots have been maintained with as little as 1 pound of nitrogen in eight years. Higher annual rates of nitrogen are sometimes used to speed recovery of the slow-growing zoysia from damage. Meyer zoysia is dormant about six months from fall to spring in the Transition Zone. However, many homeowners find the gold-brown color to be compatible with late fall and winter landscapes.
Meyer zoysia lawns and golf course fairways are susceptible to occasional winter injury. Damage is usually confined to poorly drained areas, and corrective measures should be taken to improve soil drainage in those locations. Damage may also occur where close-mowed zoysiagrass turf grows on heavy-clay ridges with exposure to heat and drying winds in summer and severe wind chills in winter.
Another problem, large patch disease of zoysia, appears most often during cooler spring and fall weather. Patches range from a few inches to several feet in diameter and continue to expand in the same location over successive years. An orange band may form on the active border of the patch. Rhizoctonia species have been implicated in this disease, which is difficult to control with fungicides. Fortunately, this disease does not kill the plant's growing points (stems and roots), and zoysia will usually recover and fill-in during active summer growth.
Two important species, Zoysia tenuifolia Willd. ex Trin. and Zoysia matrella (L.) Merr., with few exceptions, are best adapted south of the Transition Zone. Several improved seeded-type and vegetative-type zoysias are currently being tested. Presently, Zenith and Companion are two seeded-type zoysias with good winter tolerance for establishment in Missouri. They are usually seeded at 1 to 2 pounds per 1,000 square feet
The terminal buds of zoysiagrass are rolled and pointed like a pencil point. The leaf blades are short and pointed with scattered hairs. Leaves extend off the shoot at a 90-degree angle. The collars are indistinct to broad and have hairs at the margins. The auricles are absent, and the ligules have short fringes of hairs. The sheath is round and smooth and has hairs at the top of the split. Zoysia has both rhizomes and stolons.
Bermudagrass (Cynodon spp.)
- Suggested seeding rate: 1 to 2 lbs. per 1,000 sq. ft. in late May to mid-July
- Suggested sprigging rate: 8 to 12 bushels per 1,000 sq. ft. in late May to mid-July
- Mowing height: 1.5 to 2 inches, best at 1 inch
- Taller height, 1 mowing per week; short height, 2 or 3 mowings per week
Bermudagrass is not recommended for lawn turf in the Transition Zone. It is an invasive, aggressive spreader that does not recognize borders. Once established, it is difficult to eradicate. In southern areas of the Transition Zone, many lawns are contaminated with common bermudagrass to the point that eradication is impossible. In such cases, it is easier to fertilize and mow than to attempt control.
Bermudagrass is superior to zoysiagrass in heat and drought tolerance. It requires just a little more fertilizer for optimal growth than zoysiagrass. The big question for its use in the Midwest is winter hardiness. In that respect, it is inferior to zoysiagrass. Turf managers should expect moderate to severe bermudagrass winter injury at least one or two times every 10 years in the Transition Zone. However, because of its aggressiveness, bermudagrass will recover from injury more rapidly than zoysiagrass. Natural enemies of the southern bermudagrasses include nematodes, mites and mole crickets. Unfortunately, there is not much to slow its growth in the Transition Zone.
Despite its drawbacks, bermudagrass has long been popular, especially in the southern United States. Homeowners discovered that bermudagrass would make a good southern lawn grass even if it was coarse and its cold hardiness unpredictable. Early golf course superintendents appreciated its heat and drought tolerance, which meant bermudagrass required little or no irrigation during the summer. Density of the established hybrid bermudagrasses helps to exclude weeds. However, the finest quality turf requires generous fertilization (at least 1 pound of nitrogen per 1,000 square feet per actively growing month), ample water and close, frequent mowing.
Westwood bermudagrass, discovered on a fairway in St. Louis in the 1960s, probably originated as a mutation of an earlier U-3 plant, but with superior cold hardiness. Spring dead spot disease does not seem to be an extensive, recurring problem in Westwood. Westwood has been used on golf courses and athletic fields from southern Indiana and Illinois through the southern half of Missouri.
The bermudagrass cultivars Midway, Midiron, Midlawn and Midfield are all intermediate in cold hardiness and texture, between coarse, cold-hardy Midwestern strains and the finer, less hardy African bermudagrass, C. transvaalensis. These early cultivars are not seen much these days. Recently, several cultivars — Yukon, Riviera, Patriot, Northbridge and Latitude 36 — have been released and have gained much ground in the athletic field market.
The terminal bud of bermudagrass is mostly folded and flat. The leaf blade is flat and sharply pointed and may have some hairs. Leaves extend off the shoot at a 45-degree angle. The collar is narrow and has hairs on the edge. Auricles are absent, and the ligule contains fringes of hair, like zoysia. The sheath is slightly flat and sometimes hairy. Bermudagrass has both rhizomes and stolons.
Buffalograss (Buchloe dactyloides [Nutt.] Engelm.)
- Suggested seeding rate: 1 to 3 lbs. per 1,000 sq. ft.
- Suggested plugging rate: 2-inch plugs on 1-foot centers
- Mowing height: 2.5 to 4 inches
- 1 mowing every 1 to 2 weeks, depending on use (can be left unmowed)
Buffalograss is known for its endurance in the dry western plains. It is a fine-textured grass that spreads by stolons. It is best used in low-maintenance areas such as golf course roughs, roadsides, parks and low-maintenance lawns. Buffalograss can survive on as little as 1 inch of water during an entire summer. For this reason, it has been a logical choice in the Plains states by turf managers faced with the challenge of maintaining rough areas without irrigation.
Buffalograss grows best in sunny locations where rainfall ranges from about 12 to 24 inches annually, but it will become dormant during extended periods of dry weather. A soil pH of 6.5 to 7.0 is close to optimum, but buffalograss will adapt to alkaline soils where the pH exceeds 8.0.
An unusual characteristic of this species is the occurrence of male and female flowers on separate reproductive stems. Seed heads of male plants grow on stems 6 to 8 inches tall. Seed of female plants are found in burs low in the turfgrass canopy, which makes harvesting seed difficult and raises its cost.
Buffalograss should be seeded (with burs), plugged or sodded in late May to late June after soils have warmed. Rake burs (each contains three to five seeds) into soil, and then roll to ensure good bur-to-soil contact. Sod and sod pieces should be lightly top-dressed with nitrogen until they are well established. Irrigate seed and sod during establishment to prevent drought stress. Buffalograss is not competitive during establishment, but careful use of herbicides will decrease weed competition and improve the establishment rate. Irrigate only enough to retain green color during droughts. Excessive moisture will encourage weed and disease pressure.
The terminal bud of buffalograss is rolled and has short, pointed and noticeably hairy leaf blades. The collar is broad, the auricles are absent, and the ligule is a fringe of hairs. The sheath is round, smooth and split. The plant is grayish-green and has stolons only.
Soil testing is the starting point of any lawn fertilization program and is recommended each time you establish new seed. A soil test checks the pH level and the availability of macronutrients such as phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg). After seed establishment, soils should be tested every two or three years to monitor soil pH and nutrient availability.
The optimal pH range for growing turfgrasses is 6.0 to 7.0. Most Missouri soils are slightly acidic and in the range of 5.0 to 7.0. A balanced availability of plant nutrients is found in the pH range of 6.0 to 7.0. An even better range for your soil pH is 6.5 to 6.8. You will notice how important pH can be when soils are on the acid side of the scale. Many nutrients are tied up and unavailable to the plant as pH dips to around 5.0 to 5.5. When this happens, turfgrasses look stunted and chlorotic (yellow) and do not respond to additional fertilizer applications. The same holds true for a soil pH greater than 7.5 — nutrient availability declines.
Liming soil with a pH of less than 6.0 will easily and effectively raise soil pH to the desired level. Calcium carbonate (CaCO3) is the best liming material; it neutralizes hydrogen (H+) ions in the soil solution and can replace H+ on the cation exchange sites of the soil. Through this process, the pH of acidic soils is increased into a range more suitable for plant growth. However, liming materials can burn turfgrasses, especially during higher summer temperatures. Lime should be applied during the cooler days of spring and fall. Because it is difficult to get lime into the root zone of a mature turf, the ideal time to add lime is at the time of establishment, when it can be tilled into the soil before the grass is seeded.
Many testing labs will make a recommendation on their soil test report for the proper amount of lime to add, but there is a simple way that you can calculate the amount of lime needed. Take the neutralizable acidity (N.A.) number and multiply it by 25 to equal the number of pounds of lime to add per 1,000 square feet. As a rule, lime should not be applied to actively growing grass in amounts that exceed 50 pounds per 1,000 square feet per application. For a new lawn, it is acceptable to till in the entire amount required.
Use a soil probe or small trowel to sample your soil at a 4-inch depth. Pull 10 to 15 samples randomly from each lawn area. Remove any plant tissue or thatch. Mix these samples in a plastic bucket, and then pull a representative 1-pint sample from this to send to the lab. Sample problem areas separately. The University of Missouri Soil and Plant Testing Laboratory will do these tests and give liming and fertilizer recommendations for a small fee. Contact your local extension center to submit a soil sample.
Most fertilizers bought by homeowners contain, in addition to nitrogen (N), varying amount of phosphorus (P, shown on the analysis label as P2O5), varying amounts of potassium (K, shown on the analysis label as K2O) and perhaps iron (Fe) or sulfur (S). The fertilizer composition of these products is usually in a quick-release form, meaning that they release all their nutrients at once, which creates a huge flush of growth followed by a tapering growth decline over two to three weeks. Generally, annual use of these products will not create any problems, but if soil tests are showing high levels of P and K, it is not necessary to add more P and K. In this situation, a good nitrogen fertilizer alone would be sufficient. Using a fertilizer with some amount of controlled-release nitrogen provides slower feeding over six to eight weeks for sustained growth with little stress.
Two common types of fertilizer spreaders are drop spreaders, left, and rotary spreaders, right.
The goal of nitrogen (N) fertilization is to apply the right amount at the right time to promote consistent growth. Maintaining a darker, longer-lasting color and allowing the turfgrass to recuperate from damage are key to a healthy lawn. Nitrogen fertilizer does make grass grow and is directly related to how often a lawn should be mowed — another factor in the fertilizer equation.
Feed turfgrasses when they are actively growing (Table 1). Cool-season grasses should be fed primarily in the fall, with some fertilizer applications made in spring. Many spring applications are applied with a form of fertilizer that also contains preemergent herbicides (crabgrass preventers) to control annual grassy weeds. Warm-season grasses should be fed after initial green-up in the spring. They can be given N fertilizer during each month of active growth (May through August for nitrogen only, with potassium applications in September).
Late-season nitrogen fertilization of cool-season grasses, sometimes referred to as late-fall fertilization, has been used by turf managers for years. This type of fertility program involves applying much of the season's nitrogen during the late-season months of August through October or November (depending on location). Late-season fertilization should not be confused with dormant or winter fertilization. With winter fertilization, fertilizer is applied after the turf has lost most of its color during late fall or winter and is not actively growing. This differs notably from the late-season method, which requires that nitrogen be applied before the turf loses its green color in the fall. Late-season fertilization has become popular because of agronomic and aesthetic advantages that include better fall and winter color; earlier spring green-up; increased shoot density; improved root growth in the fall, winter and spring; and enhanced storage of energy reserves (carbohydrates) within the plant.
The nitrogen source used for fall application should be a type that does not depend heavily on microbial activity to cause the nitrogen to release. This means that fertilizers containing urea, sulfur-coated urea (SCU), IBDU, shorter-chain methylene ureas and ammonium sulfate are ideal N sources for late-season applications. Although SCU and IBDU are referred to as controlled-release fertilizers, the rate at which nitrogen is released from these fertilizers mainly depends on soil moisture, not on the degree of microbial activity. The use of microbe-dependent N sources for late-season applications may not elicit the desired fall/winter color response because they do not provide enough available nitrogen for plant uptake in low temperatures. However, these slow-release N sources would be ideal for spring and summer use. Examples of these would be natural organic nitrogen sources and fertilizers consisting mostly of longer-chain methylene-ureas (low in cold-water-soluble N). Research has shown that natural organic fertilizers — such as Bradfield, Milorganite, Sustane, Ringer, Nature's and Luscious Lawn — perform well in home lawn fertilization programs. A product such as Luscious Lawn, a corn gluten–based fertilizer, can also provide some preemergent activity for control of annual grass and broadleaf weeds.
Nitrogen application scheduling.
|September1||October||November||March to April2|
|Standard cool-season||1.0||1.0||1.0||0.5 to 1.0|
|Low-maintenance cool-season||1.0||1.0||0.5 to 1.0|
1All rates are in pounds of nitrogen (N) per 1,000 square feet.
2The spring application may be made with a combination crabgrass preventer.
Phosphorus (P) is a major component for energy transfer in plants. It is also required for good seedling growth and development, which makes it vitally important during establishment of new seed. Phosphorus also promotes good root development. Adequate levels of P on a soil test report would be around 25 to 35 pounds per acre. Soil test recommendations for phosphorus are based on P2O5 (the form in a fertilizer product).
Do not apply more than 2.5 pounds of P per 1,000 square feet to established lawns at one time. To calculate the actual amount of phosphorus in P2O5, multiply the amount of fertilizer needed by 0.44. There are several good sources of P fertilizers, including super phosphate (0-18-0), triple superphosphate (0-45-0), monoammonium phosphate (11-48-0) and diammonium phosphate (18-46-0).
Potassium (K) is another major component for plant growth. It enhances root growth, enhances disease resistance, improves heat tolerance, improves drought tolerance and increases cold tolerance. Adequate levels of K would be between 200 and 400 pounds per acre. Soil test recommendations for potassium are based on its form as K2O.
Do not apply more than 1.5 pounds of K per 1,000 square feet to established lawns at one time. To calculate the actual amount of potassium in K2O, multiply the amount of fertilizer needed by 0.83. Potassium sulfate (0-0-50), often referred to as SOP, is an excellent source.
Fertilizers with higher percentages of potassium or phosphorus, in addition to nitrogen, are often called "winterizer" fertilizers. Equal percentages of nitrogen and potassium equal are preferred, but are often hard to find unless you buy a commercial-grade fertilizer.
Potassium enhances cold hardiness in turfgrasses by helping plants to "harden off," that is, to release excess water from their cells in preparation for winter. Water expands when frozen, causing plant cells to burst under high water content or succulent growth. Hardening off is not as important with cool-season grasses, but it is vital with warm-season grasses, such as zoysiagrass and bermudagrass.
Warm-season grasses should not receive nitrogen applications into the fall. Final applications of nitrogen for warm-season grasses should be made in late August. While zoysiagrass and bermudagrass are still growing in September, applications of potassium during the month will help these grasses harden off for the coming winter months and increase winter survival. One or two applications of 1 pound of potassium per 1,000 square feet can be applied during the month of September on a 14- to 21-day interval. If soil test reports indicate high to very high potassium levels, additional potassium from a winterizer is not needed.
Establishment of turfgrass brings beauty to any landscape. When preparing an area for turf, do not hurry the process. Mistakes made at this time will be evident later and will cost extra in time and labor. A beautiful turf depends on many factors, including initial soil preparation.
Fall seeding of cool-season turfgrasses
Summer heat and humidity through July and August causes many people to wonder why to even try to maintain cool-season grasses, such as Kentucky bluegrass and turf-type tall fescue, in home lawns. Yet even in a difficult year, the beauty of cool-season grasses can inspire the annual rituals of renovation and overseeding. Turfgrass brings beauty and value to any landscape, and the success of a beautiful turf depends on many factors.
Late summer or early fall is the optimal time to establish cool-season turfgrasses. Labor Day weekend is usually an excellent time to start seeding preparations. Successful turfgrass establishment takes several steps.
First, perform a soil fertility test to get fertilizer recommendations. Knowing which nutrients are sufficient in the soil and which ones are needed will determine optimal fertilizer needs. The pH of the soil is also important to know. A pH range of 6.5 to 6.8 is excellent for turf establishment. A pH range of 6 to 7 is acceptable. Any lime requirements to raise pH will be specified on the soil test results. Having this information before seeding can save you time and money when trying to establish turfgrasses. Starter fertilizers (for example, 10-24-18, 6-24-24, 13-13-13) are usually recommended at a rate of 0.5 pound of nitrogen per 1,000 square feet at time of seeding, but again this depends on soil test results.
Preparation of the site includes the removal of any debris, such as rocks, and a visual inspection to make sure the grade or slope of the landscape will provide adequate surface drainage. Holes from rock removal and low water-holding pockets need to be filled in to ensure proper drainage. Poorly drained areas are detrimental to maintaining healthy turf. Site preparation should also include broadleaf weed control if infestations are high. Perennial broadleaf weeds, such as dandelion and plantain, should be controlled at this time of year. Trimec, Weed-B-Gon or Weed-B-Gone MAX are excellent over-the-counter products available to homeowners. Labels for these products usually recommend a three-week interval between spraying and seeding; therefore, start early if you first need to control broadleaf weeds.
If you choose to renovate your lawn to a different turf species (such as bluegrass to fescue, or vice versa) or you just wish to start over, an application of a nonselective herbicide (Roundup, Finale or an equivalent product) is needed to kill the old turf and any weeds. Start earlier in August when taking out an old lawn to give more time for the products to work. Always try to time your actual seeding for Labor Day weekend or the first week of September. Nonselective herbicides can be bought at any home-and-garden center; be sure to follow the application instructions on the label. In seven to 10 days, a second application may be necessary to control any areas missed in the first application. If your old lawn is totally brown, then soil preparation and reseeding can take place seven days after the final herbicide application.
If your lawn only requires overseeding to fill in thinned areas or small spots from summer disease or drought, then a nonselective herbicide is not required, and seeding can proceed.
When seeding, good seed-to-soil contact improves germination. If you choose to renovate with a nonselective herbicide, you have the option to till the soil and create a fine seedbed. After seeding, cover the tilled soil with straw at a rate of one bale per 1,000 square feet to prevent erosion. The best method of planting seed is with a slit-seeder, a piece of equipment that plants the seed about 1/4 inch deep. This method allows for better seed germination and reduces the chance that seed will wash away in a heavy rain. Other methods to ensure good seed-soil contact include using a power rake or vertical slicer. Either of these will work up the top half-inch of soil and can be used for complete or partial renovations. Such equipment can usually be rented at a local rental or hardware store for a small fee.
Seeding rates for Kentucky bluegrass should be about 2 to 3 pounds per 1,000 square feet. Turf-type tall fescues can be seeded at about 7 to 9 pounds per 1,000 square feet. Seed applications following tillage, power raking or vertical slicing should be raked in lightly to help cover the seed with soil at a shallow depth (about 1/4 inch). To improve seed distribution and stand density, seed half rates of seed in two directions.
The final step to a successful lawn renovation is proper watering. The first two weeks following seeding are the most crucial. Until seeds germinate and start to put down roots, they can easily wash away. You should keep the soil surface moist, not wet. Do not let the seed dry out once it starts to germinate. On warm, windy days with lower humidity, keeping the surface moist may require several light waterings a day. A