Orange trees are popular garden plants in some parts of the Mediterranean, with sparkling, glossy green foliage, sweet orange blossoms in the spring and the final reward of juicy oranges. As with all citrus trees, though, oranges require warmth and humidity, and grow best in subtropical regions. Some of the hot, sunny areas of Spain provide the perfect conditions for growing orange trees.
Plant orange trees in Spain in the spring, before the hot weather arrives, to give the trees plenty of time to establish roots before dealing with the heat. Plant orange trees in full, hot sun, and where there is good drainage. Space the trees at least 4 metres apart in every direction. Amend the planting soil. Mix half quick-draining soil or loam and half compost. Turn the mixture into the planting site to a depth of at least 70 cm.
Dig a hole that is as deep as the orange tree's rootball and twice as wide. Transfer the tree quickly from pot to hole or the hot Spanish air will damage the roots. Ensure that the junction of roots to trunk is at ground level once the orange tree is planted.
Give the orange tree 5 cm of water after planting. Repeat this amount of water every three days thereafter for the first two weeks. Restrict watering to every seven to 10 days after two weeks. Monitor the soil to make sure it's always moist; never wet or soaked. Adjust the timing of your watering as necessary to accommodate rainfall and weather.
Mound the soil around the tree's base before the first frost in Spain. Mound 7.5 to 10 cm of soil around the base instead of mulch, and maintain this protective layer until spring to keep the tree from freezing.
Severe freezes and temperatures under -6C will damage orange trees, even if they've become established.