Green Earth Solutions receives calls every year asking “Why does my lawn look good except for all the weeds around the edges?”
There are actually several reasons this is an issue on many lawns.
1) The concrete/asphalt of the driveway, sidewalks, curbs, and other hardscapes, gets hot during the summer. This causes the soil along these surfaces to get hot and dry out. The season turf we have in this area prefers cooler soil so it thins out or recedes. The weeds, especially crabgrass and spurge, love the hot, dry conditions and they fill in the thinner areas.
2) It is common for this area to be edged with a string trimmer and scalping the turf is common. This shocks or even kills the grass, causing the area to thin out and the weeds to fill in.
3) Sometimes a lawn care technician, in an effort to keep lawn care products off of hard surfaces, does not get enough product applied at the edges. Insufficient crabgrass pre-emergent is very common since this is commonly applied as a granular product and is more difficult to control along the edges. The added heat common in these areas can also cause pre-mature breakdown of herbicides.
4) Areas along driveways and roads are frequently driven on by mistake. The weight of a vehicle causes substantial turf damage and compaction, and of course, there is an abundance of weeds that thrive in damaged areas and actually prefer compacted soil.
You can see that there are multiple potential reasons you might be struggling with this issue. As with many lawn issues, raising the mow height can help. Leaving the edges untrimmed also might be a solution. If salt is the culprit, a calcium or gypsum application might be the answer. In almost all cases, more water will help. Or maybe it is as simple as taking the keys away from your teenager who keeps driving on the lawn!