Pulling weeds can spread weed seeds and disturb the soil, leading to seed germination. Pulling weeds can also trigger growth in weeds that reproduce through their root systems—disturbing the roots without fully removing them may cause more weeds to grow from the roots.

It usually takes between two weeks and a month for weeds to fully die off after you spray them with herbicide, but they will start to wilt within the first week. Different weed sprays produce different results, with some working more quickly and effectively than others. Similarly, some weeds are killed more easily than others. Consult your weed removal pro for an exact timeline based on their weed removal method.

Johnsongrass and crabgrass are invasive weeds that can overtake your lawn. Crabgrass is a low-growing grass most often seen in lawns, flower beds, and vegetable gardens. While you may find Johnsongrass growing in your lawn, it will also grow in pastures, crop fields, and the edge of the road. Johnsongrass is much coarser than crabgrass. If left alone, Johnsongrass can grow up to 8 feet tall. 

Pulling weeds once per month is typically often enough to keep most weeds at bay. But in general, it's best to pull weeds as soon as you spot them to prevent deep root growth and slow their spread. To make it easier, plan your weed pulling after rain or after the sprinklers run so the soil will be nice and wet and the weeds will be easier to pull. If you notice moss accompanying weeds, make a plan to remove the moss immediately to prevent damage.