Lemon trees require little pruning, but may need occasional pruning to control their size. Also prune out overcrowded branches to help prevent pest build up.
Watering depends on soil type and weather conditions. Lemons can't withstand poorly drained soils or standing water. They need regular moisture during blossoming and fruit development. Apply the water through drip irrigation for greatest efficiency.
Fertilizer depends on the age of the tree. One or 2-year old trees should be fertilized 3 times per year, applying 1/10 to 2/10 pound of nitrogen per application. Older trees can be fertilized twice per year, applying .4 to .6 pounds of nitrogen per application. Most trees will benefit from a complete fertilizer that also contains the micronutrients zinc, iron, and manganese.