The best time to fight crabgrass with pre-emergent herbicide is when forsythias tend to bloom. In the mid-Atlantic region, this is usually between April and May. Even if you're late to apply the herbicide, it’s effective as long as the crabgrass plant has fewer than five leaves.

Adding vinegar to your lawn increases the acidity of the area, which can kill quack grass present above the ground. However, putting vinegar in your yard will also kill the grass. Unfortunately, the below-ground quack grass rhizomes remain very much alive in the presence of vinegar and will soon sprout again.

Glyphosate and other non-selective herbicides can kill orchard grass, but they will also kill the surrounding plants. Also, not all areas allow the use of glyphosate due to its environmental impact—which the EPA describes as a "potential risk to terrestrial and aquatic plants and birds, and low toxicity to honeybees." Consider mechanical removal to target the plants specifically.

Ultimately, pulling weeds vs. spraying them depends on what’s happening in your yard and your personal preferences. Manual weed removal doesn’t introduce any chemicals into your landscape, targets specific problematic plants, produces immediate results, can be free if you go the DIY route, and is inexpensive with a weed service if you only have a handful of weeds. On the other hand, spraying is often preferable for severe weed infestations and situations involving difficult-to-pull weeds because it treats multiple weeds at once, is usually more effective long-term, is less time-consuming, and costs less when done by a pro.