Bentgrass, a cool-season turfgrass, requires specific care to maintain its health and appearance throughout the colder months. Understanding its physiological responses to winter conditions and implementing appropriate management strategies from fall through spring are crucial for its survival and robust recovery. This detailed approach helps prevent common winter-related issues, ensuring the turf remains resilient.
Bentgrass Winter Physiology
As a cool-season grass, bentgrass possesses inherent mechanisms that allow it to adapt to low temperatures. During the fall, it undergoes a process called cold acclimation, where its crown moisture content decreases significantly, from approximately 77% to 60%, which enhances its cold hardiness. This physiological change enables creeping bentgrass to survive temperatures as low as -35°C after proper acclimation, compared to non-acclimated turf with a lethal temperature of -8°C.
Bentgrass does not truly hibernate but rather enters a state of slowed growth, often referred to as dormancy. It can retain its green color in milder climates, while in colder regions, it may turn bronze or straw-colored. The plant’s crown, located at or below the soil surface, is vital for winter survival, as its viability ensures rapid spring recovery. Snow cover can offer insulation, which helps protect the turf from extreme cold and desiccation.
Fall Preparation for Winter Bentgrass
Preparing bentgrass in the fall is a proactive step that significantly contributes to its winter resilience. Mowing heights should be adjusted to allow for sufficient leaf blade to capture sunlight and store energy, but not so high that it mats down and encourages disease. Leaf removal is important to prevent suffocation and the development of snow mold, as fallen leaves can trap moisture and create a favorable environment for fungal growth.
Late fall is the optimal time for a “winterizer” fertilizer application, ideally around November, or earlier in colder climates. This application, typically low in nitrogen and high in potassium, helps the turf store carbohydrates and strengthen its root system before freezing. Potassium is particularly important for root growth and cold weather tolerance. Ensure the ground is not frozen, and the grass is still green but has stopped actively growing, to allow for nutrient absorption.
Adequate watering before the ground freezes is also important to prevent winter desiccation. The soil moisture level should be near field capacity when the soil freezes or the first permanent snowfall occurs, but avoid oversaturation. A fall application of a wetting agent can maximize the absorption of natural precipitation.
Managing Bentgrass Through Winter
During the winter months, ongoing management focuses on protecting the dormant turf from damage. Minimizing traffic on frozen or dormant bentgrass is important, as cold temperatures limit growth and recovery, making the turf vulnerable to abrasion and wear. If possible, restrict foot and vehicle traffic to designated paths to prevent injury to the grass.
Snow cover can be beneficial by insulating the turf; however, heavy, compacted snow or prolonged ice can lead to issues. Bentgrass can survive long periods of ice encasement, but proper drainage is still important to prevent ice formation. If ice sheets form, solid tine aeration can help release gas accumulations. Monitoring the turf for early signs of problems, such as unusual discoloration or matted areas, allows for timely intervention.
Addressing Winter Bentgrass Issues
Several specific problems can affect bentgrass during winter, requiring targeted attention. Snow mold, including pink snow mold (Microdochium patch) and gray snow mold, is a common fungal disease favored by cool, wet conditions and snow cover. Pink snow mold appears as circular patches with white-pink mycelium, particularly on short-mown turf. Preventive fungicide applications in the fall, especially in areas with a history of the disease, are effective. Raking matted grass and removing accumulated leaves also help limit snow mold development.
Winter desiccation occurs when the turf dries out due to a combination of wind, fluctuating temperatures, and frozen soil, preventing the plant from absorbing water. Exposed and elevated sites or areas with sandy soils are more susceptible. To prevent desiccation, ensure adequate fall irrigation, consider applying mulch or light topdressing, and use windbreaks or snow fencing to reduce wind exposure and encourage snow accumulation.
Ice damage, particularly from prolonged ice cover, can harm turf by creating anaerobic conditions. While bentgrass shows good tolerance to ice encasement, surviving up to 150 days, compared to 75 days for annual bluegrass, proper surface drainage can help prevent severe damage. Avoiding the creation of conditions that lead to thick, prolonged ice layers is important.
Traffic injury on frozen or dormant turf can cause significant damage because the grass is not actively growing and cannot recover quickly. This leads to abrasion and wear, especially from concentrated foot or vehicle traffic. Implementing cart restrictions, rotating traffic patterns, and increasing mowing heights in the fall can help provide extra padding to withstand winter traffic.
Spring Recovery of Bentgrass
As temperatures begin to rise in spring, bentgrass slowly emerges from its winter dormancy. The timing of this emergence is influenced by soil temperature, with vigorous growth typically resuming when temperatures are consistently warmer, often in the 80-degree Fahrenheit range. Initial care should be gentle to avoid stressing the awakening turf.
Light fertilization can aid in recovery, but excessive nitrogen should be avoided in early spring as roots have not yet reached maximum regrowth. Instead, focus on a balanced approach to encourage healthy development. Careful watering is also important to support the turf as it greens up and begins active growth. Assessing the extent of any winter damage, such as dead patches or thinning areas, allows for planning spring renovations like seeding or sodding if needed, though bentgrass germination is slow below 45°F soil temperatures.