How does weeds spread?

[shiva]

The most effective way is to pull weeds by hand. If you do not pull up the roots, they will just regrow. It is tedious and takes time, but it is the most effective way to do it.

Yeah this is the best method also should remove those weeds when they are very small because the can give problems to the side plants while pulling them out.
I am always cleaning when they are small, but was searching somthing that can help for along time.