Question: I have three dooryard citrus trees -- an orange, a lemon and a key lime. They winter in the greenhouse. The lemon is ok and usually bears nice fruit. The lime suffers in the greenhouse, frequently losing many leaves during winter. My orange looks pretty good but the fruit usually fall off when they reach the size of a large pea. What am I doing wrong?

Answer: There are many factors which could be involved in your citrus problems. First, citrus trees need good drainage but fairly moist soil. In a container grown plant this can be difficult to achieve and maintain. Container size, especially in relation to citrus species and rootstock, can contribute to a plant prone to stress. Small containers, growing media that is too "airy" (dries out too fast), and vigorous citrus species are likely to result in stress due to lack of moisture. Most citrus needs a very large container to stay happy and productive once they reach a mature, bearing age. However, it can be easy to overwater large containers. Citrus trees will drop fruit whenever stressed, especially when fruit is very still small. Lack of pollination will also result in fruit drop when the fruit is smaller than a pea. Loss of leaves in the greenhouse is most likely due to moisture stresses and/or the lower light levels of winter.