Technically, dandelions aren’t bad for your lawn, and they don’t directly kill grass. In fact, they appear in areas that are nutrient-deprived, and their long taproots can loosen the soil and bring nutrients closer to the surface. 

However, dandelions do spread quickly, and they can take over your lawn, eventually crowding out grass. This is why a healthy lawn is the best defense against dandelions.

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.

Vinegar is known to be a contact herbicide, which means it kills the foliage it comes in contact with. Because of the high acetic acid concentration, horticultural vinegar kills weeds and grass more effectively. However, keep in mind that high amounts and multiple applications can affect the soil by lowering the pH levels.

If you spray a DIY vinegar solution that contains high salt, it can disrupt the soil's structure and make it difficult for plants to grow. That's why it's vital to avoid spraying vinegar solution on areas where you are trying to grow plants and flowers. When using a mix of vinegar and soap, some say you can plant a few days after the vinegar dries.