If your lawn is getting sparse and weedy, it might be easier to kill it off and start all over with new grass seed. Scotts Roundup contains the herbicide glyphosate and will kill your grass and weeds easily. Simply spray it on the desired area. Once the glyphosate eliminates the plants, you can reseed the area, because the chemical does not impact the soil. Since there is no contamination, you can disperse new seed to create a lush, vibrant lawn.
Wait at least three days to plant grass seed after using Roundup. If you attempt to plant seeds earlier, the grass is more likely to die from the remains of the herbicide.
Remove any dead grass that remains in the yard after you've sprayed Roundup. Rake the grass up and put it in a garbage bag.
Run a rototiller over the soil to loosen it at least 2 inches deep. You can also use a garden spade if you are working in a smaller area. Rake the soil to level and smooth it.
Fill a mechanical or hand spreader with the correct amount of grass seed. The rule of thumb is to use 10 lbs. of grass seed for every 1,000 square feet.
Run the spreader over the area twice, in a perpendicular pattern. This will ensure an even amount of seed is dispersed.
Rake the soil gently with the back of a metal rake. Cover the seed with 1/4 to 1/8 inch of soil to keep it in place and encourage germination.
Lay down 2 to 4 inches of straw or hay. It acts as mulch, keeping moisture in and insulating the seeds until they sprout.
Water the grass seed to get the roots developing. Give it water with a sprinkler or hose for 10 minutes, dispersing a light spray so that one area doesn't get more water than any other.
Continue watering the seed twice daily for 10-minute intervals. Once the seeds germinate, you can cut back to once daily watering for one week.