Time

• Since oranges are a winter crop, wait until they have finished producing before you prune. When the fruit is ripe, harvest the tree and place your orange crop in a cold storage. The University of Arizona's College of Agriculture recommends pruning orange trees from late February to early March. To protect the plants from excessive heat, do not prune after mid-March. With an average high temperature of 75 and low of 50, March hints at the hot weather to come in Arizona.
  
  

Warnings

• In general, experts at the University of Arizona recommend that you don't prune your citrus tree unless the tree is having problems, such as pests or rot. In late February or March, inspect your orange tree for signs of damaged or dead branches and remove these. You can also thin the brush so that sunlight reaches the tree's interior canopy. Branches that rub against other branches should be cut, since this will damage the fruit and the wood. Aside from this basic pruning to maintain a healthy tree, do not prune your orange tree.
  
  

Yield

• When you prune your tree, you should notice that your fruit yield the next season is smaller. However, the oranges that you do have will be slightly larger than the prior year's. This is because the tree is able to put more energy into each piece of fruit. If you desire a low yield of large fruit, you can prune more vigorously. However, bear in mind that pruning is not good for your orange tree since it puts your tree at high risk for diseases or pest problems.