Hollow Coring: when and why?
Hollow coring pushes hollow tines straight up and down into the soil, ejecting organic material. This is called removing cores or pulling plugs. Coring creates space for roots to grow deeper and to receive more water, air, and nutrients, leading to more resilient, longer-lasting turf. This process is known as soil exchange. Hollow coring is also great for removing thatch.
Importantly, after hollow coring, the holes need to be filled with sand or topdressing material, or else the benefits of the soil exchange can be lost. Importantly, waiting for cores to dry can make them easier to remove.
Key benefits of hollow coring
Soil exchange: Water, air, and nutrients can reach deeper and strengthen the roots. Organic material can be removed, and topdressing or sand added to change and improve the soil composition.
Thatch removal: by removing thatch, hollow coring removes competition from the grass for the water, air, and nutrients. Thatch also puts additional stress on the grass.
Balances organic matter: Hollow coring and topdressing help maintain the ideal 6–7% organic matter in the soil profile.
Improves drainage: Hollow tine holes let water flow to the root zone, improving drainage in waterlogged areas and reducing puddling.
Deepens roots: Roots grow deeper and become more resistant to drought. Open holes allow water and nutrients to reach further down. Roots grow healthier from increased airflow.
Hollow Coring vs. Deep Tine Aeration
Aeration isn’t one-size-fits-all. Hollow tines and solid tines can both reach sufficient depths. Some turf managers prefer one method over the other, but many recognise the importance of both methods, depending on specific conditions.
Solid tining is the most standard aeration method. Once pushed into the surface, the tine heaves and ‘kicks’ up as it is pulled out, leaving a small hole. It also does not leave debris on the surface, as it does not remove material from the soil. Instead, solid tining lifts the surface. Varying the working depth helps break up the hardpan, i.e., dense, highly compacted soil.
Hollow coring does not kick. The hollow tine is pushed and pulled straight up and down, removing the core. As the next core is pulled, the previous one is ejected out the middle of the tine. Therefore, hollow coring leaves debris on the surface.
Hollow coring can be done gradually, allowing the playing surface to be used continually, dividing its costs over multiple seasons.
Hollow coring is often done at the start or end of the season for a given sport. Many golf courses hollow core in October in the Northern Hemisphere, for instance.
Why hollow core?
Managing organic material in sports turf is essential to maintain surface performance and soil health. Insufficient organic matter leads to poor cushioning and increased reliance on chemical fertilisers, while excessive build-up causes the soil to become overly saturated and spongy, potentially resulting in black layer due to decay.
Hollow coring helps remove up to 5% of this material, but without topdressing to fill the holes and dilute the remaining content, the benefits are lost as the holes naturally collapse.
According to field research by the Sports Turf Research Institute (STRI), the optimal level of organic material in the upper soil profile should be maintained between 6–7% to ensure ideal playing conditions and turf resilience.
Choosing the Right Equipment for the Job
When it comes to aeration equipment, matching the machine to your turf’s needs is critical. Redexim offers specialised solutions, including hollow coring and solid tine aerators.
The Verti-Core focuses on a hollow coring approach, though hollow tines are also available for some Verti-Drain models.
Verti-Core: Hollow Coring for Routine Aeration
The Redexim Verti-Core III is a hollow core aerator designed for fast and efficient hollow coring. It hollow cores by punching out soil plugs vertically using hollow tines, removing plugs rapidly across large areas. The machine is available in various widths.
The Verti-Core III is also built for speed and productivity. Its high working speed and belt-driven design make quick work of fairways and sports pitches.
A key advantage of the Verti-Core III is its “straight-down” tine action that consistently and reliably leaves a clean hole in a way that does not damage the hollow tine itself.
Redexim also offers the Core Collector 1200SP, which drags behind the hollow coring machine, collecting plugs in a single pass.
Conclusion: Hollow Coring
Hollow coring remains critical to a sound aeration programme. It’s the quick, dependable way to open the surface, swap out tired soil for fresh material, and set your turf up for a season of vigorous growth. Pair it with strategic solid-tine work and let roots grow deeper and turf rebound faster.