How to Care for Calamondin Orange Trees With Yellow Leaves

Check soil pH with a soil test kit. Instructions vary, depending on the kit. Calamondin trees do best in acidic soil with a pH range of 5.0 to 6.0 but will tolerate a pH of 7.0. If the soil pH is below 5.0, raise the pH with a liming agent following the application rates and directions on the package. If the soil pH is above 7.0, lower it by working pine needles, bark chips or peat moss into the soil. For container-grown calamondin trees, you can re-pot the plant in a soil mix formulated for acid-loving plants.

Provide the calamondin tree a fertilizer specifically intended for citrus trees. If you can't find this type of fertilizer, choose one intended for acid-loving plants that contains iron and magnesium. An iron or magnesium deficiency can be caused by improper soil pH and the wrong type of fertilizer. Apply the fertilizer according to the package directions.

Learn to water the tree properly. Calamondin and other citrus trees will not tolerate wet soil, nor are they drought-tolerant. When moisture levels aren't right, the leaves turn yellow and drop. Whether planted indoors or out, water the calamondin deeply when the top 2 inches of soil feels dry to the touch. Do not water again until the top 2 inches of soil are dry again.

Keep the calamondin tree in the right growing environment. Calamondin grown outdoors should to be planted in a sunny location with good air flow. Container-grown calamondin must be kept in a bright location with humidity of 50 percent. Calamondin must never be exposed to temperatures lower than 40 degrees Fahrenheit.

Avoid sudden changes to a container-grown calamondin. While it will benefit the tree to keep it outside during warm weather, make the change from indoors to out gradual. Keep it outside for two hours the first two days, four hours the next two days and increase the number of hours every two days until the tree is outside for 24 hours. Repeat the process when bringing the tree back inside when the weather cools -- two hours inside, then four, etc.