The definition of a weed is 'any plant growing in the wrong place'. This means anything from a tiny hairy bittercress seedling to a huge sycamore tree. It also covers some of the more invasive 'garden' plants, such as snow-in-summer, Cerastium tomentosum , which will take over a rock garden if not controlled.
- Alan Titchmarsh

For the purposes of this entry, we will agree with Alan Titchmarsh and consider 'weed' to mean any plant that you are trying to get rid of, or prevent from growing in the first place.

The easiest way to control weeds is to have a very relaxed view of what grows in your garden. One Researcher says:

This is why I never have weeds in my garden. You have to remove them. I just have plants that I didn't grow that occasionally I pull up to put something I did grow in its place.

This attitude means that you never