You can plant grass seed in any type of soil--but sandy soil does present some challenges. That's because sand is less dense and does not retain moisture as well as other soil types. Therefore, amendments should be made to make it more conducive to grass seed. You will also have to pay the yard more attention to make sure it doesn't dry out. Plant grass seed in a sandy yard in the spring or summer.
Prepare the yard by removing debris such as rocks, weeds and branches. Break up soil clumps larger than 1 inch in diameter. Clumps smaller than 1 inch can be left alone.
Add amendments to the soil to make the sand more conducive to grass seed. Mix in a 6-inch layer of compost. This will help the soil hold nutrients and moisture. Use a hoe or rototiller to work it into the soil in an even mixture.
Add fertilizer to the soil, following the manufacturer's instructions. Use a product high in phosphorus or a starter seed blend. Mix it in with the top few inches of soil.
Level the yard to make sure there are no dips. Water will gather in these areas and wash away the grass seed. Rake the entire area and add soil to the low spots.
Disperse grass seed with a hand or mechanical spreader. Spread out an even amount of seed so it grows in all spots. Too few seeds will leave gaps, and too many will force the grass to compete for space.
Rake a thin layer of soil over the grass seeds. Water the yard thoroughly until the ground is moist. Avoid overwatering or the seeds will float away. Continue watering once a day to encourage root growth. The sand does not hold nutrients or water well, so you need to pay it extra attention.