Quick Answer
Putting a thin layer of sand on top of newly planted grass seed can provide some benefits, but it is not always necessary. The main reasons to use sand are to help protect the seeds, improve seed-to-soil contact, retain moisture, and prevent the seeds from being washed away. However, too much sand or poor timing can also cause problems, so the pros and cons need to be carefully considered before deciding if sand is right for your lawn project.
What are the potential benefits of using sand over grass seed?
Here are some of the main potential benefits of putting sand down over newly seeded lawn areas:
Protects seeds from birds and other wildlife
Birds love to eat grass seed, so a light layer of sand can help camouflage and protect the seeds from being eaten. It can also deter squirrels, mice, and other small animals that may try to dig up and consume newly planted seeds.
Prevents seeds from washing away
If heavy rain occurs shortly after seeding, it can wash away grass seeds, especially on slopes or soil that does not absorb water well. A sprinkling of sand over the seeds can help weigh them down so they stay in place.
Improves seed-to-soil contact
Good contact with the soil beneath is vital for grass seed germination and growth. The extra weight of sand can press the seeds down into the soil, improving contact.
Retains moisture and regulates temperature
Sand can help retain moisture near the seeds by slowing evaporation. This gives them a constant supply of water needed for germination. The sand layer also moderates soil temperature, protecting seeds from extreme heat and cold.
Levels and smoothes the soil surface
A light layer of sand can help create a more uniform surface for seeding, filling in small holes and depressions. This gives the seeds an even bed for growth.
Provides stability on sloped areas
On hills, sand can aid erosion control by weighing down the soil and grass seed so rain does not wash it away down the slope. The sand particles also help reduce the velocity and impact of raindrops hitting the bare soil.
Is inexpensive and readily available
Sand is an affordable and accessible seed covering material for most homeowners. Sand can be purchased in bags at home improvement stores or garden centers if you do not have a naturally sandy soil.
What are the potential drawbacks of putting sand over grass seed?
Using too much sand or sanding at the wrong time can also create some problems:
Can inhibit seed-soil contact if too thick
While a light sprinkling of sand can improve seed-to-soil contact, too much sand can also work against it. Excessive amounts can isolate seeds from the soil below and nutrients needed for growth. Generally, 1/4 inch or less of sand is recommended.
Can cause crusting on the soil surface
With frequent watering, a sand layer over seed can form a hard crust on the soil, making it difficult for new grass blades to penetrate through the surface when sprouting.
Can increase soil temperature if dark in color
Dark or black colored sand can absorb heat, potentially raising soil temperatures to a point that harms germination and seedling growth. Lighter colored sand is preferable if this is a concern.
May blow or wash away before seeds germinate
Although sand stabilizes soil initially, strong winds or heavy rainfalls soon after application can displace it before grass takes root. Reapplying may be necessary in some cases.
Can introduce weed seeds or other contaminants
Low-quality sand may contain debris, weeds seeds, or other contaminants. It is important to use clean, weed-free sand for topdressing lawns. Washed masonry sands are a good option.
Can potentially alter soil pH or texture
Significantly changing the proportion of sand in the underlying soil can affect the pH, drainage, or texture over time. It is best to match the native soil conditions as closely as possible.
Extra step adds time and cost to seeding
Taking the time to evenly apply sand over the lawn does add one more step to the seeding process. The extra cost of materials must also be factored in.
How much sand should you use over grass seed?
When topdressing with sand, less is often more. Here are some general guidelines on application rates:
– Apply no more than 1/4 inch of sand over newly seeded areas. This equals about 1 cubic yard of sand per 1,000 square feet of lawn.
– Sand particles should not completely cover or bury grass seeds. Some seed visibility is ideal.
– Prioritize getting a thin, even layer over the entire seeded area. Avoid dumping piles in concentrated spots.
– For spot seeding bare or thin patches in existing lawns, use sand at half the rate of full seedbed preparations.
– On sloped areas, use slightly heavier sand applications to prevent runoff. Up to 1/2 inch depth is acceptable.
– Light, frequent applications work better than heavy, infrequent applications when topdressing.
– Follow manufacturer’s instructions if using proprietary seeding sands or mixes. Blends may contain polymers to hold moisture.
– Do not apply extra sand over seedings where straw, peat moss, or other mulches have already been used.
What type of sand should you use over grass seed?
Look for a coarse builder’s sand that provides these characteristics:
– Grain size between 0.5 to 2 mm in diameter – coarse enough not to tightly compact or clump.
– Sub-angular grains with some texture to grab onto seed and soil. Rounded grains may be prone to washing away.
– Triple-washed, clean sand with no Unsuitable materials like clay lumps, organic matter, or salt deposits.
– Light tan or grey color to reflect sunlight and minimize heating, avoiding darker sand.
– Free-draining and non-compactable when wet. Avoid sands with high clay content.
– pH between 6 and 7, matching most turfgrass soils. Avoid extremely alkaline or acidic sands.
– Low fertilizer or salt content to prevent seed burning. Some products contain starter nutrients.
– Weed and contaminant free with sterilization if needed.
– Affordable and readily available. Bulk quantities may be more economical for large projects.
Qualified sands include masonry sand, play sand, utility sand, or other washed builder’s mixes meeting the above criteria.
When is the best time to apply sand over newly seeded lawns?
Proper timing of sand topdressing is key to achieving the benefits without impacting germination or seedling growth:
– Apply sand immediately after seeding and before watering the seeds. Do not pre-wet the soil first.
– On hot summer plantings, apply very early in the morning before temperatures rise.
– Allow the sand to settle into seed bed under light mist or sprinkling for 10 minutes. Then water as normal.
– Avoid heavy post-seeding rains that may displace sand before it settles. Wait for drier conditions if needed.
– Do not topdress after seeds begin to germinate and sprout. Seedlings can be damaged.
– Sand application is not recommended for winter or dormant fall seedings. Use protective mulches instead.
– Take care not to bury seeds too deeply if tilling sand into the soil surface. 1/4 inch depth maximum.
Following these simple guidelines will provide the ideal grass growing environment beneath the sand layer.
How to apply sand over grass seed
These basic steps will help you successfully use sand as a topdressing for your seeding project:
1. Prepare soil and seed lawn area as required for the grass species being planted.
2. Use a drop or broadcast spreader to apply grass seed evenly over the lawn, following label rates. Avoid seed clumping.
3. Shovel or dump sand into a wheelbarrow or tractor loader to maneuver around the lawn.
4. Evenly spread a 1/4 inch layer or less of sand over the seeded area. Aim for total coverage without burying seeds.
5. Gently rake the sand to smooth and spread into a consistent layer if needed.
6. Lightly water the sand for 10 minutes to settle it into the seed bed below.
7. Begin regular watering of new grass seeds per your normal schedule.
8. Inspect periodically and reapply sand to areas where wind or rain may have displaced it.
9. Allow established grass to grow up through sand layer. Leave in place as grass matures.
10. Consider occasional sand topdressing in the future to level uneven areas as needed.
How to care for grass after applying sand
Special care is required when establishing seeded grass with a sand topdressing:
– Water frequently but lightly to keep sand surface moist. Avoid heavy water flow that could displace it.
– Consider using a seed germination blanket over sand for better moisture retention.
– Be patient! Grass may take 1-2 weeks longer to sprout than normal.
– Check for crusting issues and lightly rake areas where sprouts are having difficulty penetrating sand surface.
– Avoid fertilization until grass plants are actively growing. High salts can burn seedlings.
– Do not mow until turf is well established. New sprouts are fragile and can be ripped out.
– Reapply sand to areas where wind or rain has prematurely removed it before grass establishment.
– Monitor for weeds in bare spots and remove promptly by hand to avoid competition.
– Fill and reseed any areas that fail to germinate after 4-6 weeks. Consider reasons why.
– Adjust watering needs as coverage fills in. Mature lawns need less frequent watering.
With proper ongoing care, grass grown with a stabilizing sand layer can fill in quickly and thrive. Adjust practices as needed based on how the new lawn responds.
Alternatives to sand for covering grass seed
While sand has some benefits as a seed topdressing, other options may also be suitable depending on your specific project and conditions:
Straw
Straw is the most common protective mulch used over newly seeded areas. At 2-3 inches thick, straw moderates soil temperature and retains moisture. It is biodegradable but can temporarily inhibit growth. Straw needs securing on slopes.
Hydromulch
Hydromulch is a slurry of recycled wood fibers that is sprayed over seed. It forms a moist protective blanket that fosters growth. Hydromulch is commonly used on roadsides or steep slopes where erosion control is needed.
Compost
A shallow layer of finely screened compost or planting mix provides nutrients while helping to retain moisture and prevent erosion. It resists crusting but decomposes fairly quickly.
Peat Moss
Peat moss offers good moisture retention and a soft surface for seedlings to emerge from. But it is lightweight and can blow away or float off on steep slopes. Regular rewetting is needed.
Rolled Erosion Control Products
RECPs like jute or coconut fiber mats are designed to fully control erosion while enhancing seed germination. Products are secured over seed beds and decompose over time.
Nothing
In ideal conditions and with proper preparation, grass seeds may germinate fine with no topdressing at all. Some sprinkling immediately after seeding may still be beneficial.
Key points to remember
Some important tips to keep in mind regarding sand usage over newly seeded lawns:
– Only apply a thin layer no more than 1/4 inch deep to avoid problems.
– Lighter colored, coarse sand with sub-angular grains works best.
– Apply immediately after seeding; do not wait until after seeds start sprouting.
– Water carefully to avoid washing sand away before grass takes hold.
– Monitor new seedlings closely and adjust care methods as needed.
– Consider alternatives like straw or erosion blankets if conditions are not ideal for sand.
– Sanding established lawns periodically helps smooth uneven spots and improve drainage.
The bottom line
Sand topdressing can provide some benefits for newly seeded grass areas in the right circumstances. But it also may not be necessary or even detrimental if used improperly or in the wrong conditions. Consider the pros and cons carefully before deciding if sanding your grass seed is recommended. If you do use sand, pay close attention to proper application depth, timing, materials, and follow-up care for the best lawn establishment results.
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