Weeds may grow back when pulled out if the root is not completely removed. Invasive weeds can regrow from just a small portion of remaining root, so using a weed-pulling tool can help ensure you remove the entire root. Weeds may grow back faster if roots aren’t fully removed, and incomplete removal could cause them to spread as well.

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.

The fastest ways to kill weeds and unwanted grass include burning them, pouring boiling water on them, or pulling them out by hand, as these methods work almost instantaneously. For a quick-acting solution that works within a few hours, you can use a commercial-grade herbicide like glyphosate or a DIY vinegar, salt, and dish soap mixture. While effective, be aware that commercial herbicides introduce chemicals into your lawn. The slowest method for killing weeds is to starve them of sunlight and nutrients using mulch or fabric covers.

Poison oak is similar to poison ivy in that it's in the same family of plants. Poison oak is identifiable by its rounded-off leaves and hairy leaf texture. Tree-climbing varieties live primarily in western states while low-growing poison oak bushes occupy the eastern states. Treat poison oak like poison ivy to get rid of it permanently.