Controlling the size and shape of plants begins when they are seedlings--that is unless you actually prefer a jungle of overgown foliage. Keeping large aggressive plants in shape, and limiting uncontrolled growth, allows air to circulate and reduces the chance of disease. For smaller plants, pinching and pruning encourages dense, compact foliage and eliminates those leggy plants reaching for the sky. Even slow growers benefit from occasional pruning to improve appearance and promote good health.
Pinch seedlings when they are first planted to encourage dense compact growth. Pinch new leaves at the ends of stems between your thumb and forefinger to remove them from the stem. This forces new growth to appear along the stems of the plant.
Repeat pinching at three weeks and again at six weeks, or until the plant takes on the appearance you desire.
Prune overgrown plants by cutting stray or overgrown branches back to the overall shape of the plant.
Deadhead or prune flowers once they begin to fade to encourage continued blooms. This fools the plant into thinking it has not produced enough seed to reproduce.
Prune plants back by one-third in midsummer if blooming ceases or plants bolt in summer heat. Water thoroughly and keep soil moist until a flush of new growth appears. Most plants rebloom, although the second flush of blooms is less showy.