Challenge On High Traffic, Transition Zone Natural Grass Fields:
Bermudagrass fields thin and worn in the spring/ early summer
Kentucky bluegrass fields stressed and worn in late summer/ early fall
Possible New Solution:
Grow Kentucky bluegrass and bermudagrass TOGETHER on the same high traffic, low maintenance natural grass athletic field
Historically, cool season and warm season turfgrass work together only with cool season serving as overseeding for bermudagrass. The overseeding supplies color during the bermudagrass dormancy period of late fall, winter, and spring. Today many Sports Field Managers are going away from overseeding their bermudagrass at all with cool season. Better bermudagrass genetics sustain late fall and early spring growth, and the challenge of transitioning from ryegrass back to bermudagrass can be unique all on its own.
So why would Kentucky bluegrass and bermudagrass sustained together in a single field ever be considered for a high-traffic, low maintenance natural grass field? Simple. Having both Kentucky bluegrass and bermudagrass provides the presence of an actively growing grass during the entire growing season.
Kentucky bluegrass thrives in spring and fall. Bermudagrass thrives during summer heat. On a high traffic field that is receiving play for 9-12 months of the year, having a single grass that is actively growing for only 6 months of the year falls short of supplying the needed recovery on high use, low maintenance fields. Large bare spots can develop on bermudagrass by mid spring. Equally bare spots can develop on Kentucky bluegrass in the summer heat, especially on fields with limited or no irrigation. Thus having both grasses present gives a high traffic, low maintenance natural grass field a “growing chance” to sustain grass cover and avoid those large bare spots.
Is ryegrass overseeding into bermudagrass the same? No. Ryegrass overseeding into bermudagrass is a high maintenance, esthetic maintenance practice. Weak ryegrass is used for overseeding in order to transition out from ryegrass to bermudagrass quickly and completely during the summer months. Sustaining a stand of Kentucky bluegrass and bermudagrass together for a high traffic, low maintenance should actually reduce maintenance. The field will never be 100% of either grass, but it will also be able to sustain 100% grass cover easier.
Will I continue to seed in new grass to the field? Yes. Kentucky bluegrass and bermudagrass can both be established from seed. Additionally, if repairs are needed in the late spring/ early summer, bermudagrass sprigs and/or sod can be used to repair the field quickly and avoid the challenge of attempting to repair with cool season in the summer stress period. Continued overseeding with Kentucky bluegrass should take place in the fall and/or early spring with bermudagrass overseeding/ sprigging taking place in the late spring/ early summer. All seeding/ sprigging would take place as needed because both Kentucky bluegrass and bermudagrass are aggressive spreading grasses.
Why now? What is different that makes this possible now? 3 things.
- Improved grass genetics
- Better plant feeding technology/ techniques
- Utilization of more aggressive cultivation
Improved grass genetics: Grass varieties for both Kentucky bluegrass and bermudagrass used in the transition zone now have a completely different genetic profile than even just a few years ago. It is an entirely new world for both grasses.
Kentucky bluegrass: Kentucky bluegrass is no longer slow to establish. Take HGT from Barenbrug for example. Multiple full fields have been established from seed with HGT Kentucky bluegrass in 5-6 weeks. That fact, combined with the ability for HGT to be sustained at mowing heights as low as ½”, aggressive recovery traits similar to older bermudagrass, and being extremely drought and disease tolerant open all kinds of new possibilities for Kentucky bluegrass. Those include sustaining growth together with bermudagrass on high traffic, low maintenance fields.
Bermudagrass: Bermudagrass holding green and sustaining growth until early November in the transition zone is now possible. With the evolution of Patriot bermudagrass through cold weather areas combined with additional new varieties coming to market, bermudagrass is being grown as far north as Iowa and New Jersey. Riviera, a seeded bermudagrass variety, provides reduced but similar cold tolerance as well. These bermudagrasses are able to sustain late season growth and green up earlier in the spring. They all also illustrate an extremely aggressive growth habit to be able to establish and recover very quickly.
Better plant feeding technology/ techniques: The understanding of plant feeding as it equates to durability of high traffic fields has evolved. Research now supports that grass (warm season and cool season) fed with reduced, consistent fertilizer amounts sustains heavy traffic durability better. Kentucky bluegrass and bermudagrass are both able to be maintained strong and healthy with as little as 2-4 lbs of total nitrogen in a growing season. Reducing fertilizer needs in a mixed stand of Kentucky bluegrass and bermudagrass is beneficial to both. Less disease and stress on the Kentucky bluegrass in the summer and reduced winter injury potential for bermudagrass going into the winter. Improved plant feeding technology also helps as high traffic, low maintenance fields can utilize fertilizer products that have controlled release for up to 20 weeks at a time. These provide slow consistent feeding and reduce labor for fertilizer applications
Utilization of more aggressive cultivation: Soil de-compaction/ aeration is the single most important component of maintaining high traffic, natural grass fields. Fields that never receive any type of de-compaction/ aeration will fail, no matter what the grass species. With increased de-compaction/ aeration, the improved grass genetic varieties of Kentucky bluegrass and bermudagrass thrive, pushing deeper roots and spreading quickly. Water can infiltrate deeper into the soil to supply and sustain those roots. De-compaction/ aeration allows soil microbes to be active and improve soil health and fertilizer efficiency, also supporting strong grass growth. Ultimately, all things from increased de-compaction/ aeration lead to better plant health and density for a mixed stand of Kentucky bluegrass and bermudagrass to thrive.
High traffic, low maintenance natural grass fields are under extreme demands. Historically, working to sustain full grass cover on these cool season and/or warm fields year round has been a challenge. That challenge with turfgrass thinning/ bare spots shows up in the weak part of the year for each grass. Uniquely, the weak times are opposite times of the year. Thus growth of Kentucky bluegrass and bermudagrass together should be considered as an option for high traffic, low maintenance fields. Improved grass genetics have vastly improved, along with plant feeding technology and the utilization of more aggressive cultivation. Together, all of these create new possibilities for something that was once considered impossible!