A. Pre-Emergence weed control is simply a weed preventative for lawns and ground cover. More and more savvy homeowners are looking to pre-emergence weed control as the answer to those nasty weeds that seem to spread like, well, weeds during the spring and summer months. Here’s how it works: 
Spring and summer weed growth is stopped before it begins by the specialized application of a pre-emergence weed control barrier which is placed in the soil. As the weed seedlings start to grow, they hit the pre-emergence barrier, and they die, never getting started in the first place.
For the greatest success in lawn care, it is essential that the pre-emergence barrier be applied during the months of January and again in April (2 times per year) to control the nastiest of these villains such as grassy weeds like crabgrass, and broadleaf weeds such as oxalis and spurge.
With a proper, timely application, 70 to 80 per cent weed control is possible.
Greenway Lawn Aeration can provide pre-emergence weed control. For best results on most lawns, apply pre-emergence twice a year; In January and again in April. For best results on ground cover, flower beds and planter areas, apply pre-emergence three times a year (every 4 months) to provide a continuous control barrier for weed prevention.