A1/A4 History & Management Practices

Since the arrival of Creeping Bentgrass, Penncross has been the preferred turf of choice since the 1950’s. Since then, there has been many strides to improve bentgrass to tolerate wear, increase ball mark recovery, and heat tolerance over the past 50 years. In the early 1980’s, the release of new bentgrass varieties such as the A and G series of bentgrass has hit the market and offered an improved turf for today’s play.  These new bentgrasses, created by Tee 2 Green Company, were chosen out of existing Penncross and Penneagle bentgrass greens and cultivated to breed the new improved bentgrasses, A-1, A-4, G-1, and G-2.  The characteristics of these bentgrasses were noted to have upright growth, high shoot density, and narrow leaves that all play a part in improving wear tolerance, ball mark recovery, and heat tolerance.

The new bentgrasses, are improved over the original bentgrasses of Penncross and Penneagle, but also have their downsides that need consistent management. These new bentgrasses require intense cultural management practices such as topdressing, aerification, and verticutting to reduce the amount of thatch accumulated from their rapid growth habits and high shoot density that have improved playability. The A Series bentgrass, for instance, have a rapid growth rate from April until November (depending on climate region) which increases the amount and frequency of cultural practices for a longer period of time than Penncross and Penneagle, which typically need cultural practices more geared to the Spring and Fall time periods.


Topdressing is a major component of an effective cultural management program.  Topdressing varies depending on management style, from light weekly applications of sand to once a month heavier applications of sand . As with all bentgrasses it is important to get as much topdressing into the canopy as possible to dilute and reduce the amount of organic material accumulated.  Organic matter is simply dead leaf and root tissue that had finished its life cycle and been deposited into the root mix. Organic matter eventually, over time, will accumulate and if not managed properly will inhibit water infiltration and gas exchange between the plant and outside atmosphere causing plant death, and soft greens to name a few of the conditions.  

Typically there are two types of topdressing practices implemented

  • Infrequent heavy topdressing, performed monthly or after aerifications
  • Frequent light topdressings or a dusting of sand, performed weekly throughout the year

Infrequent Heavy Topdressing (Monthly, Aerification)

  • Primary purpose is to fill all holes and insure a smooth putting surface after an aerification
  • Provide sand to dilute organic matter if weekly applications are not applicable due to amount of play
  • Sand disappears approximately in 10-14 days during the growing season

Frequent Light Topdressing (Weekly)

  • Primary purpose is to maintain smooth playability, firmness and dilute organic matter
  • Sand disappears approximately in 3-5 days during the growing season
  • Light topdressing offers the least amount of disruption to golfers versus infrequent heavy amounts of topdressing sand


Regarding aerification, this will vary from course to course. Most golf courses in this region aerifiy two to three times a year. Once in the spring, early summer and fall.  Aerification removes organic material, compaction,  and provides open channels for air and water to infiltrate into the root zone mix.


Aerification Timing and Recovery Periods

  • Spring Aerifications (March) have an expected recovery time of 3-4 weeks to heal 100%
  • Early Summer Aerifications (May) have an expected recovery time of 2-3 weeks to heal 100%
  • Summer Aerifications (June) have an expected recovery time of 5-10 days to heal 100%
  • Fall Aerifications (September) have an expected recovery time of 2-3 weeks to heal 100%

Spring Aerification

  • Provides open channels to allow a faster build up of heat into the green, awakening the plant earlier from the colder periods of the year
  • Removes built up organic matter acculmated and compaction from the winter

Early Summer Aerification

  • Provides open channels to allow air and water infiltration in the highest growth part of the season for bentgrass
  • Removes organic material and compaction from the spring

Summer Aerification/Venting

  • Typically a small aerification hole or knife blade to provide open air and water channels in the green for expected summer afternoon thunderstorms
  • Allows water to pass through freely and prevent water saturating the green and increasing temperatures during the hottest times of the year
  • Allows Carbon Dioxide from the plant’s roots to exchange with oxygen in the air and perform plant functions like respriation to make food for the plant

Fall Aerification

  • Removes organic material and compaction from the summer months
  • Provides relief and recovery from summer heat stresses

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2 Responses to A1/A4 History & Management Practices

  1. Lloyd Gross says:

    I have been playing golf at a San Francisco area club with established A4 bent greens, now about 10 yrs. old, with a sandy based soil and a soil temp of about 60 degrees. Should we follow the maintenance recommendations in the above article ( 12/16/10 by Steffie Safrit ) or modify them in view of our location and soil temp ??

    • Steffie Safrit says:

      Every golf course has its own mirco environment that warrant many different management practices. A lot of the practices performed on a golf course are the same, but vary in timing and personal perference.

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