Q. Should bougainvillea be cut back in the winter?  I have two in large pots. I want to see them grow fuller this spring and summer. Cut back or leave them? Bougainvillea is a witty perennial shrub in semi tropical and tropical parts of the world. We can grow it in winter freezing climates because it grows back from the roots if the top part freezes. If it gets very cold, the crown or top part of the plan may die each winter this happens. In our climate we grow it as an “herbaceous perennial” like lilies and Iris. If it freezes during the winter, we cut off the top debt part and let it regrow from the roots. Otherwise, leave it alone. A. Wait until about March 1 and see if there is any winter damage from freezing. Then decide. If there is, cut it back close to the ground and let it regrow again. Winter freezing damage to bougainvillea. When temperatures drop just one degree below freezing, damage begins to occur on bougainvillea. When this freezing temperature remains for any length of time, more and more freezing damage occurs. It will grow back from the crown (that part of the stem and roots that connect the two) if temperatures do not get too cold for a long time.             If there is no winter freeze damage, make this plant fuller by cutting the stems back at various heights (so it doesn’t look like a butch haircut) anywhere from a foot to foot half from the ground. For every cut you make, three new shoots will grow and increase the density of the plant.