Ever wonder how those petunias, salvias, asters, mums or snapdragons you saw in the botanic garden got to be so full and bushy? Most likely, they were pinched. As people, we tend to avoid pinching. It hurts a bit. Plants, on the other hand, will benefit from a pinch.
When and how should you pinch? In general, when flowers reach about a foot to 18 inches in height, they can become a bit leggy, or stretchy. When this occurs, snip off a few inches from the top and the sides of the stems.
You can use a small hand pruners or your thumb and forefinger. If there are lots of plants to pinch, the pruners make it easier on the hand. Or, if the plants are on the woody side, such as with mums and taller salvias, then the pruners are called for. Most herbs and softer stemmed plants can simply be pinched with your hand.
Pinch in June, July and August. This will provide time for the plants to regrow new shoots from below the newly cut part of the stem. On the average, most plants will benefit from one or two pinchings per season. Even having extolled all of the benefits of pinching, many gardeners can't bring themselves to pinch. They just can't harm the plant - even though it will result in better looking plants in just a few weeks.