Overfertilizing Carambola Trees

Immature Fertilization

• Over-fertilizing a Carambola tree (Averrhoa carambola) is next to impossible, as the specimen demands extensive application of fertilizers in large amounts and with significant frequency. Between one-quarter and one-half pound of fertilizer should be applied to young Carambola trees every 30 to 60 days. The fertilizer should contain an ideal mixture of magnesium, potassium, nitrogen and phosphorus. The tree, a native to Southeast Asia, is grown in tropical and sub-tropical locales across the globe.

Mature Fertilization

• As the tree grows and ages, it becomes even more unlikely that any gardener will be capable of over-fertilizing Carambola trees. Mature specimens demand a huge amount of fertilizer with exceptional frequency. Landscapers or commercial growers should apply anywhere from 1 to 5 lbs. of fertilizer to the Carambola tree between four and six times annually. The fertilizer should include between 3 and 4 percent magnesium, 6 to 8 percent nitrogen, and 2 to 4 percent phosphoric acid.

Soil

• Carambola trees growing in acidic or neutral pH soils require applications of manganese, iron, and zinc every three months via a liquid spray to the foliage or dry application to the earth. Specimens planted in soil with a high pH level demand zinc and manganese applied to the foliage every two months. Carambola trees with an iron deficiency, characterized by a chlorosis -- yellowing -- of the leaves, should be treated with applications of iron sulfate to the soil once or twice annually.

Fruit

• While over-fertilizing Carambola trees is extremely difficult, this specimen that produces the edible star fruit also demands a steady supply of water. The tree begins to bear its fruit one to two years after planting and appreciates steady irrigation between the periods of blooming and harvest. In a home setting, gardeners must be careful not to over-fertilize the lawn near a Carambola tree as this competition for resources normally leads to a reduction in the size and quality of star fruit.