Citrus trees grow extremely well in the warm deserts of southern Arizona, and have been a significant commercial crop in the state for generations. The fruit produced from Arizona citrus trees has a distinctive flavor, a complex blend of tartness and sweetness, thought to be the result of the combination of warm summers and mild winters. Arizona homeowners enjoy citrus trees for their bright evergreen foliage as well as for the fresh, delicious fruit they supply.
Plant the tree in good soil. Test the soil to make sure it has proper drainage. Dig a hole where you want to plant the tree, fill it with water then watch how long it takes to drain. Soil that drains within 24 to 48 hours is preferred. Mix compost into the soil before you plant the tree to improve the nutrient-deficient soil common in Arizona.
Fertilize the tree. Citrus trees use a lot of nitrogen, which you can supply with ammonium sulfate or with fertilizers formulated especially for citrus trees. Fertilize in the spring before the buds appear on the tree. Fertilize again in May when the tree needs nutrients for full-scale fruit production. You may fertilize again in late summer to rebuild soil nutrients lost from heavy summer watering.
Protect citrus trees from frost. Lime and lemon are particularly frost-sensitive citrus trees. Even the warmest desert areas usually have a few nights each winter when temperatures drop below freezing. You must take measures to protect citrus trees from frost damage, evidenced by withered, burned leaves. Cover the tree with sheets or burlap. Garden stores also have specially designed cloths for frost protection. Young lemon and lime trees are particularly prone to damage from frost.
Supply plenty of water. Citrus trees are semi-tropical plants, not native to the southwestern deserts. They must have plenty of water to survive the hot, dry summers. Connect the tree to an irrigation system. Build a basin just beyond the dripline of the tree, the area directly below the outside perimeter of the tree's canopy. At the far edge of the basin, connect an irrigation line with a bubbler-style emitter that can fill the basin, allowing the water to penetrate down into the soil and stimulate root growth.
Protect citrus trees from summer stress. Water the tree once a week in the heat of the Arizona summer to prevent the leaves and fruit from being sun damaged. Protect the trunk of the tree from sun exposure by painting it with white latex paint. If the you don't trim the bottom of the trunk as it grows, the tree's own foliage can shade the trunk.
Watch for nutrient deficiency. If you notice yellow leaves with green veins, the tree has iron deficiency, a symptom of over watering. Apply iron sulfate or iron chelate solution by spraying it directly on the leaves, referred to as foliar feeding.