Driveway edges, or places where turf grass is thin, are terrific habitats for weed seeds to germinate and thrive. Asphalt driveways in particular, are warmer than the surrounding soil and they radiate heat. This means that plants living next to the driveway edge can start growing sooner each spring. Additionally, any weed seeds that wash off the driveway into the lawn-driveway edge, also have this warm soil advantage.
Purple Henbit, like other a winter annual weeds, grows incredibly well in moist fertile areas where it has little competition. Spring pollinators love this perfusion of small purple flowers. This mint is found all over Northern Virginia and just a few plants can produce thousands of teeny tiny seeds.
We stopped by to take a look at a driveway after being asked why the henbit is so thick along it every spring.
After carefully scouting, we consistently found flowering henbit in the low spots. This is because the tiny seeds are easily transported by rainwater. Interestingly, we discovered the henbit was by far the thickest along the left lower edge of the driveway, exactly where the car is parked every day.
Conclusion: Weed seeds are being brought on the tire treads and washing into the driveway edges when it rains.
So now that we know some of the reasons why, what is the very best way to limit weed proliferation in your lawn edges? Limit the amount of bare spots for weeds to make their home. Turn poor soil into healthy soil. Healthy soil supports a thick stand of turf that can out-compete most weeds.