While many gardeners enjoy their bougainvillea shrubs as they grow prolifically in a home landscape, sometimes bougainvillea grows out of control and you may want to remove it. With concerted effort, you can successfully kill bougainvillea shrubs by cutting back the growth severely and applying glyphosate herbicide to the cut stems. Due to the energetic growing tendencies of bougainvillea, be prepared to repeat this process several times to kill the bougainvillea shrub completely.
Use the pruning shears to begin cutting back the bougainvillea shrub. Cut the shrub down in stages, removing the top growth first and discarding it into the garbage bag.
Continue cutting and removing stems until you get near the crown of the shrub. Remove stems until you reach the main stems that are growing out of the crown of the shrub.
Cut off a main branch just above the crown with the pruning shears. As quickly as possible, apply the glyphosate concentrate to the severed stem with the paintbrush. You must apply the glyphosate within seconds for it to be effective because the plant will begin to seal up the wound (making the glyphosate ineffective).
Repeat step 3 to remove all of the main stems and apply the glyphosate concentrate to these severed stems as quickly as possible.
Monitor the condition of the bougainvillea over the next week. If you see evidence of new growth, cut this new growth off and apply the glyphosate to the severed stems.
Wait until you do not see any growth activity coming up from the crown of the bougainvillea shrub for several months. Dig the crown and the dead root system from the soil to remove the last remnants of the bougainvillea shrub. Discard all remnants of the shrub.