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Why do they put sand on aerated greens?

Golf course greens require a lot of maintenance to keep them in top playing condition. One of the most important maintenance practices for greens is aeration. Aeration involves punching small holes into the green to improve air circulation, drainage, and root development. After aeration, it is common for golf courses to apply a layer of sand into the aeration holes. This sand topdressing serves a few key purposes.

Fills in the Holes

When greens are aerated, it leaves behind thousands of small holes on the putting surface. This can temporarily make the green bumpy and uneven. Applying a light layer of sand helps fill in these holes and smooth out the surface of the green. Filling the holes with sand enables golfers to resume putting on the green shortly after the aeration process. Without sand filling, the holes would remain unfilled for a prolonged period, disrupting play.

Provides Firmness

Sand particles are quite solid and rigid compared to the organic matter in a green. Adding sand fills the pores between soil and thatch particles, resulting in a firmer putting surface. This increased firmness leads to a smooth, consistent ball roll rather than slopes or indentations on the green. The firmer surface also gives greens resilience against divots and damage from golf shots.

Adjusts Soil Composition

Over time, the soil composition of a putting green can become compacted or develop a layering effect. Topdressing with sand helps break up these layers and alters the physical structure of the green’s soil. This improves drainage, aerates the roots, and creates a more consistent putting surface from top to bottom. Routinely adding light layers of sand gradually improves the soil. Golf courses may topdress greens several times per year as part of their agronomic programs.

Encourages Growth

In addition to the physical benefits, sand topdressing provides agronomic benefits to the turfgrass plants themselves. The sand particles work their way into the turf canopy, acting like a light abrasive on the leaves and stems of the plants. This abrasion helps reduce excessive thatch accumulation and encourages the plants to grow new, upright leaves. The sand also provides weight or pressure on the plant crowns to promote growth and tillering. These effects lead to a tighter, denser, and healthier putting surface.

Aids Seeding

Courses performing seeding operations in conjunction with aerification greatly benefit from sand topdressing. The sand provides good seed-to-soil contact for the grass seed, which is vital for germination. The layer of sand also helps retain moisture near the surface, keeping the seedbed wet. This moisture retention provides ideal conditions for the grass seed to sprout and establish. Using light, frequent sand topdressing after seeding will encourage the development of a uniform stand of turfgrass.

Provides Smooth Consistency

Following greens aeration, the surface can be left patchy, uneven, and bumpy due to residual soil cores. Topdressing smooths out this irregularity in the putting surface for a consistent ball roll. Sand fills in low spots and holes, while also building up thin or weak areas. The result is a uniformly firm and smooth green ideal for putting. As an added benefit, sand particles gradually work into the aeration holes to help accelerate the healing process.

Improves Playability

Perhaps most importantly, sand topdressing improves overall playability following aeration procedures. Golfers want to be able to putt smoothly on green surfaces after aerification. Leaving the holes unfilled with sand would mean waiting days or even weeks for the greens to fully heal. Topdressing provides an instant fixing solution to restore the putting surfaces back to playable condition almost immediately. This makes the disruptions from aeration much shorter for golfers.

Enhances Visual Appeal

In addition to performance benefits, sand topdressing also provides aesthetic benefits. Seeing torn-up, unfilled holes on putting greens is unappealing to most golfers. A light sand dressing gives the green a clean, consistent, and pleasing appearance. The sand also incorporates over time to make the aeration holes less visible. Golfers are much more receptive to aerification programs when the greens are smoothed over with sand compared to left in a dotted, uneven condition.

Allows Customization

Not all greens require the same amount or type of sand after aerification. With topdressing, superintendents can customize and adjust the sand application based on the individual needs of each green. Some greens may receive lighter sand quantities, while others get heavier amounts. The sand particle size and shape can also be tailored to each area. This flexibility allows the topdressing regimen to be adapted across the course or even on different areas of a single green.

When Is Sand Applied After Aeration?

Timing is an important consideration when topdressing greens after the aeration process. In general, sand is applied immediately following core removal. Spreading the sand right after aerifying allows it to filter into the holes while they are fresh and open. This provides maximum filling of the holes to smooth the surface. Courses using bigger tines or more aggressive aeration may come back the next morning to do a second sand application to ensure adequate hole filling.

Sand topdressing is almost always done on the same day as aeration, but the timing varies based on when the aerification occurs. Early morning or late afternoon/evening aeration may be followed by sanding during the same morning or afternoon. Mid-day aeration could have the sand worked in right before or right after the process. Proper planning ensures the sand is ready to be applied at the appropriate window after aeration.

How Much Sand Is Used?

The amount of sand used for topdressing greens after aeration can range quite a bit based on the goals of the course. Here are some general sand quantity guidelines:

  • Light topdressing – Around 5 cubic yards per 6,000 square feet
  • Moderate topdressing – Around 10 cubic yards per 6,000 square feet
  • Heavy topdressing – 15+ cubic yards per 6,000 square feet

Keep in mind that these are rough estimates and usage will depend on many factors like aeration density, green size, turf health, and desired smoothness. Superintendents monitor the greens during sanding and adjust volumes accordingly to achieve hole filling without over-application.

What Type of Sand Is Best?

Golf courses utilize specialized sand blends designed for topdressing greens. The ideal sands have certain characteristics:

  • Sub-angular/rounded shape – Provides smooth ball roll
  • Silica composition – Resists compaction
  • Medium size particles – Work into turf best
  • Free of stones/debris – Prevents plant damage
  • Washed – Removes fine particles for drainage
  • Consistent texture – Even distribution

In some regions, native sands meeting these criteria are available. In other areas, custom greens sand mixes are blended. Having the right sand leads to effective filling of aeration holes without detriment to turf health.

Sand Application Methods

Topdressing sands are worked into the aeration holes using either drop-style fertilizer spreaders or dedicated sand injector machines:

  • Rotary/Drop Spreaders – Basic application method where sand is spread evenly across greens. Requires additional watering and dragging to work sand into holes.
  • Sand Injectors – Specialized vertical mowers that drop sand directly into the holes as tines vibrate across green. More efficient sand incorporation.

When using rotary spreaders, best practice is to make two or three lightweight passes applying 30-50 lbs of sand per 1,000 square feet with each pass. Going too heavy on one pass can overload the green. Gentle dragging and irrigation between passes helps work the sand into the holes. Using a calibrated sled ensures uniform depth and smoothing.

What Happens After Topdressing?

Once the sand has been applied and worked into the aeration holes, some additional steps help smooth and heal the greens:

  • Light rolling/dragging to further blend sand into turf
  • Irrigation to wet sand and soften surface
  • Grooming with specialized greens brushes
  • Mowing greens with sharp reels to stand turf upright
  • Rolling again to provide final smoothing

This process needs to be gradual over several days following topdressing to prevent damage and encourage healing. Frequent rolling and mowing brings the greens to an ideal playing condition in the days after aerification.

Potential Issues with Sand Topdressing Greens

While extremely beneficial, sand topdressing does require proper precautions and execution to prevent potential problems, including:

  • Overfilling holes leads to buried turf and excess sand left on surface
  • Too much sand can smother plant leaves prohibiting growth
  • Sand particles that are too fine can seal aeration channels
  • Excessive watering causes sand to wash out of holes
  • Insufficient water leaves dry, loose sand that is easily displaced
  • Dragging before irrigation can brush sand off greens

Careful sand selection, calibrated application rates, controlled irrigation, and proper follow-up procedures minimize risks and provide maximum results from sand topdressing.

Alternatives to Sand Topdressing After Aeration

While sand is the most common material used, some other options for filling aeration holes include:

  • Soil – Native soil from aerification plugs can be screened and returned as topdressing.
  • Compost – Composts and humus materials contain organic matter to mix into the holes.
  • Peat Moss – Light and absorbent for temporarily filling holes and retaining moisture.
  • Vermiculite – Porous mineral absorbs water and aerates soil when worked into holes.
  • Calcined Clay – Granular non-swelling clay that fills holes and provides drainage.

However, sand remains the topdressing of choice. It provides the best blend of smoothing, firmness, and soil amendment when applied appropriately after greens aeration.


Sand topdressing is a critical process following greens aeration to return the putting surfaces back to ideal playing condition as quickly as possible. The sand fills the aeration holes to smooth and stabilize the surface. It also provides key agronomic benefits like encouraging plant growth, improving drainage, and gradually enhancing soil composition. Proper watering, dragging, and rolling after topdressing ensures maximum incorporation. When done correctly, sand topdressing provides an instant solution to the disruption of greens aeration for better putting and healthier turfgrass.