WATER; Although potted trees are especially vulnerable to dryness, most watering mistakes involve overwatering. Sun exposure, hot or windy days, and air-conditioning will increase the need for watering, while cool cloudy days have the opposite effect. As a rule of thumb wait until the top inch or two of soil is dry to the touch, and then water by slowly filling the container until thoroughly wet.
FERTILIZER; You can use a slow-release formula every two months, or a liquid feed every other week. Look for a mix that includes the micronutrients iron, zinc, manganese, molybdenum, copper, and boron. Read and follow label directions, and watch your trees. Fertilizer problems usually show up at first as discolored of misshapen leaves.