Bougainvillea grows outdoors in the subtropical climates of California and Florida and is a popular container annual in other climates. The shrub produces colorful flower bracts in hues of red, magenta and peach. Since bougainvillea only grow on new growth, gardeners need to actively manage their bougainvillea to ensure a steady stream of flowers. Pinching and pruning are the gardener's tools to do so.
Look for new growth, which will have pale green stems. Old growth stems turn woody with age.
Locate a growth shoot 1/2-inch down from the stem's tip, off to the side. Snip the developing shoot off the bougainvillea plant with your pruning shears. Alternately, grab the shoot with your thumb and forefinger and pinch it off.
Repeat this process along other new growth stems on your bougainvillea. Pinched plants develop more new growth, which results in more color.
Pinch the bougainvillea regularly, working in this manner. How much you pinch is up to you; there is no limit to how much pinching is acceptable, according to the Houston Chronicle.