Answer: Pinching means trimming off the individual growth tip of a branch or stem. The growth tip would be the dominant top of the plant. Each time you do this it causes the plant to rebranch again, at the spot where you nipped it, thus growing denser. You can do this with a scissors or more quickly by literally pinching them off with your thumb and index finger. (The newest growth at the tip of a seedling for instance is very soft and tender.)I hope this helps.
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