Over time, given lack of maintenance, an old gravel car park can seem a bit worn out. Gravel can shift and areas can become bare. You could attempt to cover up the gravel with a grass lawn, but sod will not put down roots there and seed may not establish well in the compacted soil beneath the rocks. But this does not mean you should give up hope on transforming your gravel lot into a grassy lawn. Grass will grow in around gravel if a proper seed bed is prepared.
Break up the soil beneath the gravel, using a spade and rake. Loosen the soil to a depth of 12 inches. Mix the gravel with the soil. The angles of the gravel will help to aerate the compacted soil.
Spread a 4-inch layer of organic soil amendments such as peat moss and compost over the soil. Mix the amendments into the gravel and soil beneath them. The amendments will help aerate and condition the soil and provide nutrients for the grass seed.
Mix 1 part grass seed with 5 parts masonry sand. Grass seed typically is too fine to be used in a broadcast fertiliser spreader. Place half of the seed mixture in the fertiliser spreader and push the spreader in a grid pathway over the gravel plot.
Place the other half of the seed into the seed spreader. Push the spreader in a perpendicular pathway to the first grid pattern over the gravel plot.
Rake the seed bed, using a leaf rake, to cover the grass seed to a depth of 1/4 inch.
Water the grass seed with a garden hose and hose-end sprinkler. Use the equivalent of 1/4 inch of rainfall up to four times daily until the grass seed sprouts. Gradually decrease the amount of water to 1 inch once a week.