Angel trumpets flower once a month. Angel trumpets are generally easy to care for. They can be grown in a range from bright light to full sun. They are not fussy about the soil in which they are grown; however, though they like water, they do not tolerate saturated soil. Angel trumpets do best when in cool weather, though some plants tolerate hot weather better than others.
In a climate that has cold winters, they need to be protected in a greenhouse. If a greenhouse is not accessible, carry it through the winter by keeping it in a cool dry location. Despite the fact that it will lose its leaves, they will return in the spring when the light intensifies. Every couple of months after flowering, give them a fairly hard pruning. That consists of removing one third of the length of the biggest branches and any weak branches. In August or September, prune the bush even harder, cutting out all weak branches and cutting back the major branches considerably. Angel trumpets are moderate feeders; do not be afraid to fertilize them. It is best to fertilize them with palm special immediately after pruning. The easiest means of propagation is by layering or cuttings. They seldom set seed in warm climates. Unfortunately, angel trumpets are prone to spider mites, especially but not exclusively indoors. They will be plagued by a virus infection if allowed to grow too long without the benefits of pruning and fertilizer.
(2) http://www.smgrowers.com/brugman.htm
These plants all can become trees in mild climates and will remain evergreen although they tend to loose some leaves in the winter and will freeze back to their larger stems, or even to the ground, when temperatures fall much below 25°F. Flowering can occur at any time of year but is heaviest in summer through early fall. All of these plants are extremely fragrant, especially in the early evening when a single plant can perfume large areas of the garden. Plant in full sun to medium shade and give ample water from spring to fall. Prune to shape annually after last frost in spring.