Pinching, otherwise known as tipping, is a pruning method generally used on young plants to encourage branching.
Pinching and Tipping: What, Why and When
Too, these terms can be used when referring to the removal of plant buds to discourage branching. Confusing, right? Once explained, these techniques are easy to understand and valuable to use.
When a plant begins to grow from seed, it usually breaks through the soil as a single stem upon which leaves begin to form. And, it will continue to grow in this single stem formation indefinitely if not pinched. Eventually, the plant will begin to allow new buds to open, causing the plant to become bushy. However, growers can stimulate bushiness early in the plant's growth by simply removing the tip of the plant manually. This is desirable because it can help develop full, lush plants rapidly. And, it can be done on some plants like Fuchsia to keep hanging baskets and flower beds lush for the growing season. Yes, it will mean flowering starts later, but in the end the look can be much more beautiful.
Do note: Pinching must be done properly and should not be performed on more mature plants, woody shrubs or trees. When trees are "tipped" this is called "topping" and can be seriously detrimental to your plant.
Here's how to pinch (or tip) properly: Once your young plant has formed a few pairs of leaves on a stem, it is ready to be pinched. Plants grow buds at the base of each leaf, just above the point where the leaf connects to the stem. This is called a node. The stem between each pair of leaves on a plant is called the internode. To stimulate these buds to open and form new branches, remove the growth just above the leaves. While you want to remove as much of the internode as possible when pinching, it is important not to damage the tender buds growing at the base of the leaves or they will not grow properly after you finish your pinching work. Use your fingernails or a small tool like a micro-snip for this kind of fine, delicate pruning.
Once you have pinched your plant to remove the top growth, the remaining buds will be stimulated to begin growing. Within a few days, you should see new the remaining buds begin to open and form new stems. Eventually, those new stems will form new leaves with buds at their bases. Once these new stems have a few pairs of leaves, you may repeat the pinching process on them, which will force those branches to bush out even more. When pinching plants multiple times, avoid pinching branches below a point where you have already pinched. And, once your plant is sufficiently bushy, stop pinching flowering plants like Fuchsia so the flowers will form. Edible herbs like basil are best harvested via pinching, which encourages new edible growth and discourages flowers and seeds. When flowers and seeds form, their growth may inhibit further production of the tasty herbal leaves.
Because pinching is done on tender growth that is easy to remove by pinching the growth between our fingers, the term is also used to refer to the removal of new shoots to deter growth. In plants like tomatoes, stems often form more side shoots and get bushier than we want. In order to control this growth, growers may choose to pinch out some selected buds along the stem to reduce how much of a jungle the plant forms. This can also encourage a plant like tomatoes to put energy into forming more fruit on the remaining stems.
To pinch out side growth, choose a small emerging bud at the base of a leaf, and pinch it out with your fingers or micro-tip snips (insert link). If you get behind on your pinching, these shoots can be removed even after they have emerged and begun to grow. Once removed, usually they will not grow back, so be sure not to remove all of the side shoots on a plant or it will not branch out at all.
Remember: Pinch to remove all growth above a leaf to encourage bushiness. Pinch budding growth from just above a leaf, but do not remove the internode and growth above that leaf, to reduce bushiness. And never try to pinch a mature woody plant or tree; this is called topping and can be detrimental to trees and other mature shrubs.