Build a new green on a shaded site that has poor air circulation and you can anticipate a slow, agonizing grow-in.

Bentgrass Putting GreenEstablishmentAvoid the perilous pitfalls frequently encountered during grow-in.by BOB VAVREK

YOU HAVE decided to build anew golf course or perhapsrebuild a green or two on an

existing course. From the minute theputting surface is seeded there usuallywill be a considerable amount ofpressure from owners and members,and the pressure you put on yourself,to open the green for play.

Mistakes made during the grow-in ofa sand-based bentgrass green can delaythe opening date significantly. Theworst -case scenario? The turf fails andthe new green again must be taken outof play to be reestablished. Follow thesetips and avoid the pitfalls, and you will

have the golfers complaining aboutdifficult hole locations faster than youcan say, "I'm glad I followed USGAGuidelines. "

Tips For Success -Do Your Homework

Have potential root zone materialstested by an accredited lab regardlessof construction method. Do not rely onold test results from the supplier or thetest results obtained by friends acrosstown when they rebuilt their greens.The physical soil testing lab shouldalso perform quality control testingduring the blending operation before

the root zone mixture is delivered to thegreen site. A list of accredited physicalsoil testing labs can be found at:www.usga.org/green/coned. A sampleof the root zone mixture should also besubmitted to a chemical soil-testing labto determine nutrient levels. Porosityvalues, percolation rates, and nutrientanalysis provide valuable informationyou can use to fine-tune the fertilityprogr~m and irrigation practices duringgrOW-Ill.

The adage "you can't make a silkpurse out of a sow's ear" rings truewhen an attempt is made to build agreen using questionable materials.

SEPTEMBER/OCTOBER 1999

Following USGA Guidelines is a hugestep in the right direction toward ex-periencing a smooth grow-in. A wealthof experience and know-how fromother superintendents who have suc-cessfully established USGA greens andfrom the Green Section staff alreadyexists. Review the USGA Guidelinesand watch the USGA Putting GreenConstruction video. Tips for establish-ing a green are also available from theUSGA website (www.usga.org) or con-tact your Green Section agronomist.

Don't Make TheSame Mistake Twice

Why was it necessary to rebuild anold green in the first place? Denseshade, poor internal or surface drain-age, restricted air movement, severecontours, a lack of putting surface toaccommodate the amount of play at aparticular course, and a variety of otherfactors can lead to the demise of agreen. To help remedy the situation, cutdown trees, use a construction mix thatdrains well and resists compaction, andprovide ample putting surface for theanticipated amount of play. The for-mula for failure is to take a small,heavily shaded, severely contouredgreen out of play and build a similarsmall, heavily shaded, severely con-toured USGA green in its place. Agood tool to evaluate the overall grow-ing conditions of the green site is thearticle "Helping Your Greens Make theGrade," found in the March/ April 1998issue of the Green Section Record.

ShadeExperience from the field strongly

suggests that bentgrass greens need atleast eight hours of direct sunlight eachday for a consistent rate of growth anddevelopment. Expect a long, agoniz-ing grow-in if you build on a shadedsite. Greens in full sun will be ready toopen weeks before shaded greens.Eliminate as many trees as possiblefrom the south and east sides of newgreens to ensure morning sunlight.Need a challenge? Try to establish turfon a green where morning sun has beenlimited by mature evergreens.

Timing Is EverythingMany green construction projects

that are attempted across the northerntier of states suffer because the green isseeded too late in the season to provideenough time for bentgrass to grow,develop, and harden-off before winter.For example, a green that is seededduring the second week of August inWisconsin will usually be ready toopen the following spring, sometimeduring early June. Seed the same greenduring late September and the greenmay require the entire next season forgrow-in.

Late summer or early fall generallyis considered to be the best time toestablish a new bentgrass green, butthe specific optimal seeding dates varywith location and climate. Across thenorthern tier of states a new greenneeds to be seeded by mid-August if aJune opening date is anticipated. The

recommended seeding date can bepushed more into early to mid-Sep-tember in some parts of the transitionzone.

Soil temperatures generally are highduring late summer, and bentgrass willgerminate quickly, usually within five toseven days. Heat and drought stressbecome less of a concern as the daysbecome shorter. Seedling diseases,such as damping off, that accompanyextended periods of heat and highhumidity are less likely to occur inlate summer as daytime and especiallynighttime temperature/humidity mod-erates. In addition, weed encroach-ment is much less of a problem duringfall compared to spring.

A spring seeding results in the mostchallenging grow-in because the imma-ture seedlings must survive heat stress,weed pressure, and erosion from wash-outs that accompany afternoon thun-derstorms. A relatively dense stand ofcrowded immature bentgrass seedlingsis especially susceptible to turf diseases.Also, mechanical stress from mowingand topdressing applications is more ofan issue during summer compared tofall.

Seedbed PreparationUse soil test results as a guide to

determine how much starter fertilizerto incorporate into the seedbed duringthe final grading operations. A rule ofthumb used with success by manysuperintendents is to incorporate a1-2-1 ratio starter-type fertilizer at a

Don't step up to the plate with two strikes against you. Always have the physical properties of a potential construction mixtested by an accredited lab and use sound construction techniques such as the USGA Recommended Guidelines forPutting Green Construction.

2 USGA GREEN SECTION RECORD

Walk-behind mowers equipped with solid front rollers are recommended tominimize stress to the immature stand of bentgrass during grow-in, especiallyalong the perimeter of the green where the constant turning of grooved rollersusually injures turf.

rate of approximately lIb. nitrogen per1,000 sq. ft. of turf into the upper rootzone just prior to seeding. Incorporat-ing Milorganite or another source ofnatural organic nitrogen into the seed-bed is also a common practice. Use arate of approximately 5 lbs. of Milor-ganite per 1,000 sq. ft. of putting surfaceand lightly till the fertilizer into the topfew inches of root zone during finalgrading.

Seeding RateSeed most modern varieties of bent-

grass at a rate of 1 to 1.5 lb. per 1,000sq. ft. of putting surface. Use a lIb. ratewhen using the ultra-dense varieties ofbentgrass such as G-2 or A-4. Seed inat least two directions to ensure uni-form coverage across the entire green.Mix bentgrass seed with a lightweightcarrier such as a natural organic fer-tilizer to facilitate a more uniform dis-tribution of seed through a dropspreader.

Maximize Seed-to-Soil ContactA common practice is to use the

knobby tires of a motorized sand raketo press the seed into the soil. Invari-ably, the first seedlings to germinate arethose at the bottom of the tire depres-sions. Various types of light rollers alsohave been used to press the seed intothe construction mix. The importanceof adequate seed-to-soil contact can-not be overemphasized.

MulchApplying a clean straw mulch or

hydromulch to a green after seeding isa technique that is rarely consideredanymore. Mulching to prevent wash-outs and to maintain more consistentmoisture levels in the upper root zoneafter irrigation was once a commonpractice. Perhaps the presence of moresophisticated irrigation systems thatcan be programmed to deliver frequent,light irrigation to turf in a uniformpattern has eliminated the need tomulch, and maybe not. Even a lightstraw mulch would be worth its weightin gold if it prevented just one washoutof a recently seeded green.

Extremely lightweight geotextilefabric, such as Seed Guard, can be usedin place of straw or wood fiber mulch.These polyspun fabrics allow freemovement of air and water through thecover and do not trap an excessiveamount of heat during a sunny day.They are inexpensive and disposable.Covers have been used with varyingdegrees of success to extend the grow-

ing season later into the fall and initiateturf growth earlier in spring.

Disease ControlUse seed treated with Apron to pre-

vent damping off disease if the greenis seeded during a period of hot, humidweather. Treating a new green fordiseases is a challenge since mostcommon golf course sprayers are tooheavy and would cause wheel ruttingacross a putting surface during grow-

in. Use granular fungicides on newgreens and be sure that the materialschosen for disease suppression are safeto use on immature bentgrass. Be surethe person using the spreader is com-fortable with the equipment and thatthe spreaders have been carefully cali-brated. Another option is to have awalk-behind boom-type sprayer avail-able for use during grow-in. This typeof sprayer could also be used to applylight rates of soluble fertilizer to spoonfeed the new greens. In fact, somesuperintendents prefer the walk -behindboom sprayer to the more commonmotorized sprayer for putting greenmanagement.

IrrigationOpinions vary greatly regarding the

proper method of irrigating a newgreen. Too much irrigation is thetendency prior to seed germination.Frequent, light irrigation is believed to

be much more important after seedgerminates. A seed probably will notdie if the surrounding soil dries out, buta seedling will.

The importance of dependable, uni-form irrigation coverage is often under-estimated during establishment be-cause most superintendents believe theautomatic irrigation system can alwaysbe supplemented with hand wateringor roller-based sprinklers. Unfortu-nately, a sprinkler head that does not

function properly may not be discov-ered soon enough to prevent seedlingdieback, and wind may disrupt theuniformity of irrigation coverage evenwhen the system is functioningproperly. Moisture levels across theentire surface of a new green need tobe checked several times a day duringhot, dry weather.

How one interprets light and fre-quent irrigation can have a significantinfluence on the rate of turf growth anddevelopment. The weather dictates irri-gation needs, since more frequent irri-gation cycles are needed during a dry,windy day and less irrigation is neededduring a humid, cloudy day. Conse-quently, the irrigation clocks mayneed to be adjusted to accommodatechanges in the weather patterns. Irri-gation frequency can be reduced as thestand of turf matures. Check the depthof the root system and adjust irrigationcycles accordingly.

SEPTEMBER/OCTOBER 1999 3

Frequent irrigation and high rates of nitrogen applied to an immature stand of turfwill invite damping-off disease during extended periods of hot, humid weather.

Neglect the topdressing program and uneven areas on a new green will often beseverely scalped as the height of cut is lowered throughout the establishment period.

gen analysis fertilizers can easily bedivided and spread across a green intwo or three directions. Most naturalorganic fertilizers also provide slow-release micronutrients to the root zone.

Phosphorus levels also must bemonitored. Typically, 1 lb. of phos-phorus per month for the first coupleof months during grow-in is sufficient.Micronutrients are easily appliedthrough one or two applications of amicronutrient package such as O. M.Scotts' STEP product.

Poor fertility management of sand-based greens is probably the numberone mistake made by superintendentsduring establishment. Oftentimes,heavy applications of soluble fertilizersare made at infrequent intervals. Thenthe rate of nutrient release is expectedto last as long as the same fertilizerapplication to a mature green. Theimplications of frequent irrigation orheavy rainfall over an immature turfgrowing on a sandy root zone are notconsidered or understood. The unfor-tunate result is thin, wide-bladed, off-color turf that is starving for nutrients.

TopdressingSome superintendents are successful

using high-quality straight sand fortopdressing throughout the grow-in.Washed mason sand that has a majorityof its sand particles between 0.25mmand O.5mm in diameter (medium sand)is a safe bet for topdressing greens.Medium sand has a desirable balancebetween moisture-holding capacity and

some other form of slow-release nitro-gen. A monthly 1 lb. rate of slow-release nitrogen can serve as the foun-dation of the fertility program duringgrow-in, and the weekly light appli-cations of soluble fertilizers sustainvigorous bentgrass growth anddevelopment.

Furthermore, there is practically nochance of burning the turf or causinga flush of growth using natural organicsources of nitrogen. Skips or overlapsare rarely a concern because low nitro-

.Sand-based greens typically are over-watered during the grow-in becauseporous root zones accept water readilywithout puddling. Heavy irrigationcycles will do little more than movesoluble plant nutrients beyond the rootzone and encourage disease activity.Granted, immature bentgrass seedlingscannot tolerate much drought stress,but soaking greens several times a dayis counterproductive.

Should an extended dry period occurduring grow-in, it may prove necessaryto periodically water more deeply. Thecombination of frequent applicationsof fertilizers and frequent, light water-ing can result in a buildup of salts inthe upper root zone. These can usuallybe flushed by a 0.25- to O.5-inch rainor irrigation application.

FertilityUse the initial soil test results for the

root zone mix as a guide for how muchfertilizer to add to the upper inch ortwo of the green just prior to seeding.Once the turf begins to grow, a goodrule of thumb is to apply about ~ lb.of nitrogen every 7 to 10 days for theentire first season of establishment. Useturf color as a guide to fine-tune thefertilizer rates. When the bentgrassneeds to be mowed on a consistentschedule, the amount of clippings permowing also can be used as a guide forfertilizer applications. If soil tempera-tures are above 60 degrees, try to sup-plement the more readily availableforms of nitrogen with Milorganite or

4 USGA GREEN SECTION RECORD

A poor grow-in effort ... can you find the putting green in this picture?

drainage. Other superintendents areequally successful using the originalroot zone mix during the first year ofestablishment and then switching to acompatible straight sand once the standof turf matures and begins to recycleorganic matter into the upper rootzone.

The straight sand option is stronglyrecommended if the sand componentof the root zone possesses a relativelyhigh percentage of coarse and verycoarse sand particles. A coarse rootzone mix that meets USGA Guidelinesmayor may not be suitable as a top-dressing material. When in doubt, seekadvice from a USGA agronomist.

Topdressing applications during thegrow-in serve several purposes. Lightapplications of sand level out unevenspots across the slope of a green thatcould become scalped by mowerswhen the cutting height is decreasedthroughout the grow-in. A commonpractice is to apply a relatively heavyapplication of sand to greens just priorto lowering the height of cut. The sandsupports the mower a little higher andslightly raises the effective height of cut

for a few days until the sand settles intothe turf. As a result, frequent topdress-ing reduces the potential for scalpingseedlings as the height of cut is slowlylowered.

Topdressing helps prevent excessivethatch from accumulating in the upperroot zone during establishment. A littlethatch or cushion is desirable and isone of the signs that a green can beopened to play. However, a distinctlayer of dense thatch should not beallowed to develop. Too much thatch,a common occurrence during grow-ins, can slow the movement of waterthrough the green and cause otherconcerns when the putting surfacematures.

Use a spinner-type fertilizer spreaderwhen topdressing to keep the unstableroot zones from rutting during the firstfew weeks of grow-in. Once the surfacefirms up, try to use more conventionaltopdressing equipment, but only fillthe hopper full enough to topdressone green. Keep brushing and otherabrasive operations to a minimum. Tryto water- in the topdressing or use a verylight cocoa mat or a piece of upside-

down artificial turf to work sand intothe green.

Inadequate topdressing or no top-dressing at all probably is the secondmost common mistake made duringestablishment. Try to match topdress-ing applications to the growth of theturf. Another common mistake is plac-ing a full load of sand into the top-dresser and then trying to sand four orfive greens at a time. The heavy unitusually causes severe rutting that maytake weeks, months, or years to smoothout. For every green where too muchsand is applied to the putting surfaceduring establishment, there are over ahundred greens that receive inadequatetopdressing applications.

The Initial Mowing OperationHand mowing is necessary during

grow-in. Keep the cutting units sharp.Use solid rollers to reduce physicaldamage to the seedlings, especiallyalong the inside perimeters of the green.Roll the green to firm up the playingsurface before the initial mowing.Walk-behind units can be run acrossthe green with the reels off to roll the

SEPTEMBER/OCTOBER 1999 5

putting surface pnor to the initialmowing.

The most common height of cut forthe first mowing is approximately ~"for the ultra-dense varieties of bent-grass and about %" for other bent-grass varieties. Mow the greens duringthe afternoon when the turf is dry.Start mowing when a small amountof clippings will be removed from mostof the green at the initial height ofcut. Collect the clippings during theinitial mowing and then return clip-pings in subsequent mowings to re-cycle a little organic matter to thesurface of the green, which serves aslow analysis fertilizer and lightweightmulch. Maintain the green at a heightof cut not lower than %2" for the entirefirst season. The exception would be alower initial season mowing height ofW' when establishing the ultra-densevarieties of bentgrass.

Superintendents generally err onthe side of waiting too long to initiatemowing. Rarely is a green mowed toosoon. The initial mowing often removestoo much leaf tissue and the growth ofthe turf is set back for several weeks. Ifthe mowing height is adjusted, forexample, to )!z" to account for excessivegrowth, it may take the entire seasonto safely lower the height of cut to aplayable ~6".

The other mistake is trying to main-tain the turf during establishment usinga triplex mower equipped with groovedfront rollers. The symptoms of theinjury this practice causes to a weakstand of bentgrass seedlings are un-mistakable. The perimeters of thegreens are thin or bare, along with turfacross humps and along severe slopes.Triplex mowers also can cause ruttingof the new green before a dense standof turf develops.

When is the Green Ready to Open?This is the question that you will be

asked throughout the grow-in, andthere is no clear-cut answer. A verygeneral rule of thumb for bentgrassgreens is to allow at least three monthsof good growing conditions beforeopening to play. Most greens are seededduring fall and opened the followingseason. How many of the marginalgrowing days during late fall, winter,and early spring account for the "threemonths of growth" is impossible todetermine. My personal, unscientificcriteria for opening a green are as fol-lows: If a wedge is cut from the greenand is difficult to tear apart due to (1)the knitting of bentgrass stolons and(2) the development of a thin layer ofthatch in the upper root zone, then thegreen is ready to open.

Unfortunately, pressure from golfers.or financial considerations usually re-sult in the green or greens being openedfor play too soon. Very few superin-tendents have had the luxury of seed-ing a green during fall and having theentire next season to grow-in andgroom the turf before opening to playthe following spring.

Finally, avoid setting a specific datefor the opening of a new green, becausethat date will likely be chiseled in stoneby the golfers. The weather duringestablishment will have a considerableinfluence on how quickly the stand ofbentgrass develops. Make sure thegolfers understand the influence ofweather conditions and the risks ofplaying a green too soon. It always willbe very difficult to close a green afterit is finally opened to play. Avoid theneed to even consider such an un-popular decision by following theadvice in this article to stack the oddsin yo~r favor for achieving a rapidgrOW-ln.

BOB VAVREK is the Green Sectionagronomist responsible for the westernportion of the North Central Region. Hisgrow-in was in the Cleveland, Ohio, areaand he now resides in Milwaukee)Wisconsin.

Supplement automatic irrigation with careful hand watering to maintain consistent levels of moisture in the root zone.Avoid one of the more common pitfalls during the grow-in: overwatering the putting surface.

6 USGA GREEN SECTION RECORD