Angel's Trumpet (Brugmansia)

Q. My tree [angel trumpet tree (brug.)] is in a pot where it gets only a few hours of sun each morning. It produces flowers but lately the leaves have been turning slightly yellow. Does it need a larger pot or more sun?

A. Angel's trumpet Brugmansia features blooms dangling like great trumpets or bells from the large shrubs and range from 7 to 14 inches long depending on the species. Brugmansia may be grown in containers or in the garden in a fertile moist but well-drained soil. Grow in full or part sun. The plant may grow as tall as 15 feet especially following a mild winter.

I suspect that your plant may need on or both of these:
more sunlight as 2-3 hours is insufficient
more nitrogen as the yellowing foliage could be deficient in this necessary element.

The flowers begin to appear in spring continue in fewer numbers in the summer but pick up again in the cooler fall months. Apply a balanced [20-20-20 is good] fertilizer monthly during the growing season. Plants should be heavily mulched for the winter. Plant tops will freeze but new growth from the roots usually appears each spring.

Container-grown plants moved indoors for the winter may bloom during those months. You can propagate brugmansia from cuttings. Take 5-inch-long cuttings from half-ripened wood in the fall and root in a good potting soil. Eight to 10 cuttings fit nicely in a gallon pot.

Use a balanced slow-release fertilizer but use a high-phosphorus fertilizer on those plants that are reluctant bloomers. Use a high-nitrogen fertilizer to green up your yellowing plant.