Question
I am the owner of a wonderful orange tree that my mother started from seed in 1987.  I have had it for 18 years, and it is about 61/2 feet tall.  I keep it outside in the summer and bring it in in the fall.  It has flowered once, weakly, but never borne fruit.  I am heartbroken because it is dropping all of its leaves while they are green and the color of the bark seems lighter. It began showing signs of stress in late December. Here is what I have checked for:

No sign of spider mites and no webbing. No holes in the bark. I water it when it is pretty dry, which I check by putting my finger in the soil. I fertilize it 4 times a year with a timed-release fertilizer for fruiting & flowering trees (last done around Christmas). I have not repotted it for two years; it is in a large platic pot, as it always has been. I keep it in a window with an Eastern exposure, it probably gets 10 hours of sunlight a day. No sign of being root-bound; leaves look perfectly normal, but they just drop off. No animals in the house and no odor in soil, no fungus in evidence.

Please help me- this is the last tangible link I have to my mother who died several years ago.  I love this plant.

Answer
Hi Ann,

When a plant that has done well for many years suddenly starts to fall apart, I usually look for some change in its normal environment - a reduction in light, repotting, drop in temperature, pest infestation, et. al. However, there is nothing that you have described that suggests an environmental change. If you think you may have overlooked something (an unusually cloudy winter, for example), please let me know.

Otherwise, I would have to conclude that there is a root problem related to your watering routine. You can let me know the height of the tree, the diameter of the pot, and how often and how much water you typically apply OR you can do the following:

The next time your tree is dry enough for you to water, unpot it before you water. Inspect the rootball. The top quarter of the soil should be moderately dry and the bottom and interior of the soil should be damp, but not wet. The roots should be wrapped around the outside of the rootball and they should be firm and wirey. If the soil is very dry all the way through, then you have ben underwatering - either too infrequently or not thoroughly. If the soil is wet and the roots are soft, then the problem is root rot due to keeping the soil too moist. Either condition can cause green leaves to drop off, but it is far more common with over watering.

Light may be related to this. A citrus really needs as much direct sun as possible. An east exposure provides only a few hours of morning direct sun, which is considerably less than ideal. In reduced light, it is very easy to overwater because the plant grows more slowly and needs less water in reduced light.

Please let me know if any of this is unclear or if you have any additional questions.

Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC

You can E-mail me directly at: [email protected]

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