For 3 years, I've grown a white angel's trumpet in a large pot. Over winter, I keep it in the sunroom until it is warm enough to move back outside onto the patio. The plant produces a constant display of flowers, but the leaves drop off in summer. I water it regularly and it doesn't seem to show insect damage. Do you have any suggestions?
Your plant may have a moisture or fertilization problem. Check the roots to see if the plant is potbound. If so, move it to the next size container. Adjust your watering and wait to fertilize. If this isn’t the problem review the watering and fertilizing routine. Water the plants thoroughly, so the excess runs out of the drainage hole, whenever the top few inches of soil is crumbly and moist. This may be everyday in the summer. Outdoor container gardens also need more fertilization than plants growing in the ground. Add a slow release flowering plant fertilizer to the soil surface after the plants have adjusted to their outdoor growing conditions. Every time you water you will be giving the plant a little bit of fertilizer. This will help replenish the nutrients washed out of the soil by frequent watering and those used by the plant to produce the abundant flower display.