What is hollow tining or coring
Hollow tine aeration which is sometimes referred to as coring is the process of removing soil / thatch from the lawn. Hollow tines are small circular tubes that are pressed or punched into the base of the lawn, each time they penetrate a core is removed. This form of lawn aeration has many benefits:
- Aids the breakdown of thatch / organic matter – As hollow tining physically removes thatch from the lawn, it is an excellent way of removing vast quantities, keeping the thatch in check and at a manageable level. It also has a beneficial effect on the soil organisms, which are important for the natural thatch breakdown.
- Relieves soil compaction – This type of aeration typically creates more airspace than other methods, such as spiking and slitting and will have a greater impact on relieving compaction.
- Improves surface drainage – Coring helps keep the lawn drier and firmer by removing surface water. This helps reduce many lawn care problems including moss, turf disease and certain weeds.
- Integrate top dressing into the soil profile – Hollow tining is great way of getting a suitable soil / sand mixture (top-dressing) into the soil profile prior to top-dressing. It will also help seed germination and establishment if it is carried out prior to over-seeding, especially if the seed is mixed in with the top-dressing.
- Increase soil temperatures – Removing water and increasing air space in the upper soil profile will increase the soil temperature, promoting better grass growth.
- Increases pore space – Allows oxygen to enter and carbon dioxide to escape the soil, resulting in healthier growing conditions.
Implements & machinery used for coring
There are numerous types of coring implements and machinery. These range from a simple hollow tining fork to specialized coring machinery used by turf professionals.
The most basic and cheapest type of implement is a hollow tine fork or hand corer. Like a garden fork it is fitted with four or more tines, but in this case hollow tines instead of solid tines. It is great for small tight lawns, where maneuverability with a machine could be a problem. They do a very thorough job and penetrate deeper than most machines. The obvious drawback is they are very time-consuming and can be hard work.
The next method is a petrol powered or towed machine where the tines are fitted to a rolling or rotating cylinder or drum. This method is ideal for larger areas of turf where maneuverability is not restricted. On this type of core aerator the tines penetrate to a maximum of 50mm. The main drawback is the cost of the machine and in most cases hiring would be the best option.
Finally there are machines that have a punch action. The tines are fixed to a cam and punched into the soil. These machines are very expensive and are used by the professional turf care industry. However a growing number of lawn care companies are using them and they can also be hired.
Hiring is probably the best option, as hollow tining is only carried out annually / biennially a year on a typical lawn.
Timing and ground conditions
Like any type of lawn aeration the ground conditions need to be suitable, more so in the case of coring. The tines are more fragile and prone to breaking, if used on dry or stony soils.
The soil needs to be moist enough for the tines to penetrate with relative ease. If they are hard to push in, or the machine bounces around then the soil is too dry and damage to the tines or machine may occur.
If the lawn is waterlogged or too wet, you may actually contribute towards surface deterioration and damage lawn further. So it is important to wait for the right conditions before carrying out a coring program.
Although coring can be undertaken at any time during the season, ground conditions permitting, late summer / early autumn is the preferred time. There are a couple of reasons why the end of the growing season is preferential.
Hollow tining can be quite disruptive and the lawn needs a while to recover. Recovery is usually quick at this time of the year, as there is still plenty of warmth left in the ground, which produces strong grass growth.
Coring complements other renovation programs that are often carried out during this period, such as de-thatching, overseeding and top-dressing.
Preparation and core removal
Once the ground conditions are suitable for coring, you can plan your program. If possible mow the lawn a little shorter than normal (without stressing the grass), prior to coring. This will make it easier to collect the cores and help any further treatments, such as overseeding and top-dressing.
Although not essential, try to hollow tine when the grass is dry, as this will help prevent any stickiness or smearing on the lawn surface. It can be a messy job if it undertaken in adverse conditions, especially on heavier, clay soils.
Unless the aerator is fitted with a collector the core will need removing from the lawn. They can be removed by a number of methods including using a shovel, sweeper, blower, rake etc. Some hollow tine aerators are fitted with wind-row boards which leaves the cores in a row. This enables the cores to pushed into heaps and then shoveled into a barrow and carted away.
Once the cores have been cleared you are free to continue with other tasks such as over-seeding and topdressing etc.
In some situations the cores can be broken down and the soil / root-zone is worked back into the lawn, while the thatch can still be removed. This is common practice on light loamy soils when the primary goal is to remove thatch. A besom broom or drag mat can be pulled over the cores (once they have dried) to separate the thatch from the soil.
The soil will be returned back to the lawn to act as a top dressing and the thatch can be removed and disposed of. If you go down this route, choose a dry, windy day and the exposed cores should dry out very quickly. The soil should crumble easily (once dry) and be easily worked back into the turf.