Putting the Numbers to PGRs

Whether your profits are getting squeezed or your budgets are getting cut, plant growth regulators (PGRs) can help you stay on track with substantial savings in your property management programs. First introduced for use on fine turf in 1987, PGRs have proven their value in turf and ornamental management earning them a well-deserved reputation as an indispensable tool. A well-thought-out PGR program has repeatedly demonstrated reductions in the costs associated with labor-intensive tasks such as mowing, trimming, clean-up and hauling by 50 percent or more.


The first step in developing a plant growth regulation program is to determine your objectives. What would you like to be able to accomplish by adding PGRs to your programs? Many managers feel they get the most from their PGR programs during the peak spring growing season when the demands for mowing and trimming are high and the weather often erratic. During this season, properly timed PGR applications can slow growth to make mowing easier and faster, or hold turf growth to reduce the number of mowings. Hazardous or hard to mow areas can be put on hold for up to eight weeks to reduce potential accidents and liability.

“What I often tell people who call to inquire about PGR use,” says Doug Obermann, product manager for PBI/Gordon Corporation, “is that I like to use a PGR on my own lawn during the peak season.” Obermann goes on to explain that you can stretch out your mowing requirements and get by with every 10 to 14 days instead of the twice weekly mowings that are generally required during peak growing season. Additionally, mowing takes less time and there is less strain on the mower. Clipping volumes are also reduced, which can be even more important to contractors who may have to double mow or bag and haul the clippings.


Many contractors do not use PGRs in the highly visible areas they maintain, but choose rather to use them in the back of the property in areas that need to be kept trim and neat, but not necessarily have the immaculate lines of freshly mowed turf. And many managers find PGRs especially valuable when they can skip some of the mowing required to keep steep embankments or areas with high vehicle traffic that may make mowing hazardous to employees, but still need to be kept neat and trim.


Seedhead suppression is another PGR benefit that is sometimes overlooked by property managers. Often it is the stem and seedhead that makes a turf area look ragged and in need of mowing. When the production of stems and seedheads is suppressed, turf areas can retain a lush but maintained appearance much longer. To achieve seedhead suppression, you must make PGR applications prior to the development of the seedhead, but after full green-up of the turfgrass. One way to assess the timing is to watch for early seedhead production along curbs and drives where a warmer “micro-climate” may cause early seedhead development. If you see this, you need to be getting your seedhead suppression application made right away, according to Obermann. “I worked with a Kansas county maintenance supervisor,” relates Obermann, “who tried a PGR along his roadsides to reduce mowings. The application was made early enough to also suppress the seedheads. When they finally did mow, the manager called to tell me that the roadsides looked like a park because the usual mowing debris — clippings, stems and seedheads — was no longer a problem.”


Labor-intensive trimming along curbs, sidewalks and driveways can also be reduced. “In meetings I ask ‘Who here loves to string trim?’,” says Obermann. “And in 18 years not one single person has ever raised their hand.” String trimming is labor intensive, time consuming and, therefore, a drain on profits. PGRs are ideal for reductions in string trimming and many property managers use them exclusively to keep string-trimmed areas neat. Obermann offers the following application tip: “Don't scalp the turf and then apply a PGR.” The grass has to have sufficient leaf tissue to absorb the product, he explains.

Another tip for turf managers — ALWAYS make sure you are controlling the broadleaf weeds. The PGR treatment will not suppress the growth of the weeds, so failure to control them can ruin a neat appearance. Since most property managers are making broadleaf weed applications anyway, they can realize another cost savings by tank mixing the weed control and PGR products and applying them together. When this is done, the cost of the PGR application is eliminated for even more savings.


Virtually every turf manager can benefit from the use of PGRs, says Obermann.

Golf course superintendents may use them in the roughs to hold off the need for mowing, for Poa annua seedhead suppression in bentgrass fairways or even for prevention of bermudagrass encroachment into sand bunkers.

Contractors generally don't want to reduce the frequency of mowing, but can definitely gain a competitive edge by reducing the time it takes to mow and the clippings that have to be double-mowed or hauled for disposal. Often this will allow a reallocation of labor to other tasks that generate additional profit.

On-site grounds managers also enjoy the ability to reallocate labor to other tasks. It doesn't net them profit, but it does help keep budgets in line.

Industrial vegetation managers can reduce mowings of roadsides and trimming around utility poles and other obstacles. PGRs are widely used to tame cool-season grasses along roadsides and on hazardous embankments.

First-time PGR users are encouraged to experiment. Determine your objective, then select a product to work with that fits that objective. Review product claims and discuss the potential benefits with a representative from the manufacturer. Company representatives are generally able to provide some suggestions concerning proper application of their products and may even be available to assist with the first application. They can also assist in the development of an initial PGR program designed to meet the needs of your specific situation.

Make sure your sprayer is calibrated. Uniform application at the correct rate is essential for PGR success. Over application can result in uneven suppression and discoloration of the turf. Make sure your application timing is appropriate for your objective. Make your first application in an area designated for experimentation or on your own turf. Before making an application on a customer's property, make sure they know what you are trying to accomplish. Making your very first PGR application on a client property is not recommended. And leave an untreated plot so you can gauge the growth regulation effect. The side-by-side comparison will be your best measure of your success.

Use the potential savings calculator formula provided on page 33 to determine what your potential savings, based on your identified costs, might be and then try out your program on a limited area for the first year. You may save even more than you anticipated! But do evaluate your program and make adjustments where required. Put the numbers to PGRs and put them to work for you.

Laylah VanBibber, marketing manger at PBI/Gordon Corporation, has worked with the professional greens industry for 20 years reviewing research, talking to professional turf and ornamental managers and preparing product literature and articles.


Do make sure that the turf to be treated is in optimum condition at the time of treatment, generally in spring or fall.

Don't apply to grass that is showing signs of insect infestation or disease. Insect and disease damage will be more obvious in PGR treated turf, which cannot replace damaged blades.

Don't apply to grass in areas subject to concentrated traffic from people, animals or vehicles. The only defense grass has against traffic wear is to grow.

Don't make a PGR treatment on grass that has been scalped; sufficient leaf tissue for absorption is required for success.

Don't waste your PGR treatment on dormant plants. Wait until green-up is complete.

Do delay initial spring PGR applications in mixed species turf to make sure the slowest recovering species have greened up sufficiently to be sprayed.

Do make seedhead suppression applications prior to the emergence of the seedhead from the sheath. Seedheads which have already emerged will not be controlled.

Do make a pre-emergent crabgrass application and a broadleaf weed control application prior to or with your PGR treatment.

Do mow grass to be treated at a summer mowing setting so that there remains sufficient green and foliage to mask aging grass blades and thatch.

Do remove strewn grass clippings or tree leaves before application to assure contact with grass foliage.

Do try to apply PGRs at least eight hours before irrigation or before rain is expected.

Do read all label directions prior to making your PGR application.

Don't entrust inexperienced applicators with PGR applications. Proper timing, precise dosages and uniform, even coverage is essential to a successful growth regulation program.

Do make sure that the PGR is applied evenly; skips will result in an uneven appearance; overlaps may cause discoloration.

Don't make your PGR application when there are high winds, which could cause the spray pattern to be uneven.

Don't allow a plugged spray tip to create embarrassing gaps in your boom sprayer's coverage.

Don't mow turf for at least three days after application; mowing will remove any PGR that has not yet been fully absorbed.

Do monitor and adjust irrigation: PGR treated plants require less water during the suppression period. Too much water may damage treated plants.

Table 1. Calculate your PGR savings potential
Costs Included in Mowing and Trimming Formula Your Costs
Labor: Persons assigned to job. Actual cost depends on equipment and terrain. Typical time to mow one acre is 2 to 4 hours per acre. Hourly wage × time to mow (2 hours) = $
Travel Time: To and from job site. Average estimate 20 minutes. ⅓ hour × wage = $
Labor Burden Costs: Other costs of labor-employer, social security, workman's compensation, insurance, etc. Typically 30 percent of wage. 30 percent of wage × mowing and travel time (2 ⅓ hours) = $
Equipment Fixed Costs: A $5,000 purchase price for mowing/trimming equipment spread over 6 years, operating at 500 hours per year. Depreciations cost/hour = $1.67 Calculate your depreciation: Cost of equipment divided by 6 years divided by 500 hours = $ $
Equipment Operating Cost: ½ gallon fuel consumed/hour 1 gallon fuel @_________ $
Equipment Maintenance Cost: Maintenance cost for labor to change oil, grease, sharpen blades, etc. ¼ hour × wage = $
Fuel and Vehicle Expenses: Vehicle expense to transport mowing equipment and personnel to and from job site. Per mile cost = 42 cents. Assume 10 miles round trip @ 42 cents per mile = $4.20 $4.20
Parts and Supplies: Replacement for blades, oil, grease, filters, etc. Add your own_____ (This can be a significant expense if mower blades must be replaced frequently.) $
TOTAL COST FOR 8 WEEKS OF MOWING Average number of mowings × “Total Cost per Acre” $
A. PGR Product Costs — Based on MSR for Embark Turf and Ornamental Growth Regulator at a 5 pint per acre rate $28.15 $28.15
B. Application costs when applied with a regular scheduled broadleaf herbicide application. $0 $0.00
C. Application costs when applied as a separate application About the same as mowing cost per acre $
TOTAL PGR APPLICATION COST Add A + B Or A + C depending upon application decision $
TOTAL POTENTIAL SAVINGS Subtract “Total PGR Cost” from “Total Cost for 8 Weeks of Mowing” $


Applications of PGRs can:

  • Reduce string trimming — keep trimmed edges along fencelines and around posts, poles, trees, gates, lights, monuments, statues, benches, metering equipment and sprinkler heads looking neat for weeks.
  • Reduce clippings and the labor associated with bagging, hauling, double mowing or blowing.
  • Free up labor for value-added tasks that give you a competitive edge.
  • Reduce labor and equipment wear associated with mowing.
  • Let you skip mowing steep hills, rocky areas, ditch banks, medians or other hazardous areas, in or near streets or roads and rough areas, which could damage mowing equipment or endanger mower operators.
  • Keep groundcovers from growing over driveways, walks or walls, or encroaching into turf, flowers or other defined areas.engines, but the effective difference between a 3.5-hp saw and a 3.7-hp saw may not even be noticeable. Conversely, two saws with identical engine size or power might cut very differently due to other design factors.

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