How to Grow Grass Between Flagstones

The first thing you need to do is to clean up the area between the flagstones to make sure you have a debris-free area. Eliminate any stones and make sure you have good soil to start off with. Good soil is the key to good, healthy grass. If you have this to start, then you can skip the soil preparation and go right to the planting of the grass step.

Next, you want to determine how much sun you get in the flagstone area. This will determine if you need a shade turf or regular grass seed. Recommended shade turf:
fine fescues; tall fescues, including creeping red, chewings. (Reference 1; first page paragraph 1 of website.)

After you install the flagstone, you usually need to amend that soil if you want to plant around it because a lot of sand gets mixed into your soil when you lay down a flagstone. Calculate the square feet of the area where you want to plant the grass. Use bagged soil amendment -- this can be mixed right in with the sand and the old soil. Assuming a lot of sand is mixed in with the old soil, you can use three bags for every 24 square feet. Sandy soil requires you to add more nitrogen to the soil via organic material. This would be in the form of composting, mulches or manure. (See References 2; page 6 soil management chart.)

Turn over the soil around the flagstone with a round nose shovel. Carefully work the soil around the stones, so as not to break or damage them. Break any large clods of dirt. If large clods are forming, then you need to work when the soil is drier. Remove any large rock or debris at this time.

Add the soil amendment as per instruction on the bag. Spread the amendment to all areas using a shovel. Make piles and then use a garden rake to spread it out evenly. For large areas, you might want to even use a wheel barrow.

Once the amendment is evenly spread, use a shovel to work the amendment in. Again, take care not to damage the stone or move it. Use the garden rake to achieve your final grade.

Your finished grade should be one inch below the top of the flagstone on a two inch thick flagstone. When you place the top of the soil an inch below the level of the stone, this prevents any dirt or debris during a heavy rain from washing over the stone and covering it.

Rake a wire rake lightly over the prepared area. Apply the seed with a hand spreader. Use the same spreader to spread some low-nitrogen fertilizer, so as not to burn the seed. An NPK rating for nitrogen, phosphorus and potassium of about 10-10-10 is a good start. One 50 pound bag of fertilizer will cover 5,000 square feet of area.

New grass should be watered three time a day for a week (You can get away with twice a day in the fall.) Each week you should water one time less. Finally, in the last week, you should water only one time a day, every day. Grass will take ten days to sprout.