Yes, Johnsongrass is a hard weed to kill. It has the ability to grow fast and spread even quicker, so it requires a detailed plan and thorough application to eliminate it. The best plan of action is to kill Johnsongrass while the weed is establishing itself by hiring a lawn care professional or following the steps above. 

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. 

It’s best to pull weeds when the soil is wet, as it’s much easier. Wet soil is much softer than dry soil, making it easier to pull the entire weed up by the root. Also, since the soil is wet, the roots will let go of the soil and slide up with less resistance. Be careful when working on your wet garden, though, as wet soil is easier to compact, which can harm your plants.

Typically seasonally, but tailored schedules depend on local conditions and plant types.