Mango trees (Mangifera indica) and orange trees (citrus sinensis) will grow fine together as companion trees. Both are sensitive to cold and will not tolerate living in regions that are prone to freezing and frosts. It is best to plant mango and orange trees outside in the tropical and subtropical regions of the United States. They will both grow well in USDA planting zones 9 and 10. Because both have the same basic growing requirements, selecting the appropriate area to plant them will be your biggest obstacle.
Consider how large the mango and orange trees will be at maturity when selecting the planting site. Mango trees can reach a height of 65 feet and have a width of 25 feet. Orange trees can reach a height of 50 feet and have a width of 20 feet. Both require proper air circulation, so select a site that will be large enough for each to grow properly.
Select an area in your landscape that receives full sun conditions during the day. Both the mango and orange tree require sunlight to grow properly and produce fruit. Do not plant the fruit trees in a shaded area or they will grow poorly and possibly die.
Select the location you will plant the orange tree and place the mango tree approximately 30 feet from that location. Remove any weeds or grass within a 3-foot diameter around the planting site for both trees. Keep the area free of vegetation at all times after planting each tree. Do not mulch around the trees or they might develop root rot.
Amend the planting site for each tree to make sure they drain well. Mango and orange trees will not survive in soils that retain water or is prone to sogginess. Work organic material such as compost or manure into the planting site, digging it approximately 1 foot into the soil.
Dig a hole for each tree that is three times larger than each plant's root ball. Remove the mango from its container, being careful not to injure the plant's taproot. Situate the mango into the hole and fill it halfway with soil. Stomp down on the area to release any air pockets and then fill the hole the remainder of the way with soil, stomping down again.
Remove the orange tree from its container and situate it into its hole. Fill the hole with soil as you did for the mango tree. Be sure to stomp down on the soil to remove any air pockets.
Water each tree deeply after planting. Continue to water the newly planted trees two to three times per week for the first three weeks. Continue a watering schedule of once per week, depending on your weather conditions. Cut back the watering schedule to once every two to three weeks, in the fall and winter.