Esperanza (Tecoma stans, also known as yellow bells, yellow trumpetbush or yellow elder) is a perennial, semi-tropical shrub to small tree that is native to the hot, dry regions of the Americas. In many areas, annual freezes keep the plant small. But esperanza can grow very large without freezes, and may need to be pruned or trained.
Esperanzas can be trained into tree form in areas where they do not freeze to the ground each year. It is not necessary, but may allow light onto surrounding plants. They may also be pruned and trained onto a trellis to keep them from growing wide, though they are not vines: they will not cling to the trellis, so they must be tied down.
Once esperanza blooms fade, pruning them from the bush will help promote more flowering. Additionally, removing any of the long seed pods that the plant forms will not only increase blooming, but will also reduce the chances of esperanza escaping into the wild in regions of the United States where it is considered invasive. The plant will still bloom continuously even if it is not pruned in this manner, but each flush of blooms is more profuse.
According to Mary Rose Duffield in "Plants for Dry Climates," pruning esperanzas heavily in the spring or later in the growing season to keep its size in control will reduce its blooming throughout the season. Esperanzas get very large in regions with very long growing seasons coupled with winters where they do not freeze back each year, so plant them to accommodate to their maximum size.
In areas where esperanza freezes to the ground each year, pruning the new growth tips at the first flush will encourage branching without sacrificing very many blooms. In these areas, esperanza will only grow to half its tropical size, which can be as large as 10 to 25 feet tall and wide.