Question
Hi,

We have an orange tree in a pot which we bought about 3 years ago. It's about 4ft high now, probably 3ft when we bought it. It has been repotted once, shortly after we bought it. Since then, we've occasionally fed it with citrus food. It is in the house over the winter then out in the garden from about May-October.

When it arrived it had small fruit on it but they fell off and we've never had the new year's fruit grow to any significant size since. (We get the flowers and the small green pre-fruit, but they then fall off.) The sales literature says it should produce fruit 4 times a year. This is definitely not happening!

This winter we made a mistake (I think) by leaving it near a radiator. All the leaves have dropped off bar one, which is hanging on in there! I've checked the roots and they look OK so I think the leaf drop is due to the heat, not overwatering.

Also, it's had a scale insect infestation for a couple of years. We have traditionally spent hours de-scaling manually. However,  following advice from forums, at the same time that the leaves were dropping off, we made up some ultrafine oil and sprayed the leaves (leaf) and empty branches a couple of times. This looks to have killed off the scale insects but the branches now all look rather dead - the green colour had drained away from the stems apart from the one leading to the solitary leaf.

So - what would some sensible next steps be? We're not sure whether to cut off all the dead-looking branches (which would not leave a lot left) or whether life might reappear in them. Our other citrus plant (a lime) is busily producing new leaves right now so we figure it's about time that new leaves appeared but as yet no sign. Also, after applying the oil to kill the scale insects, should we then rinse it off with water. We're wondering whether the oil has suffocated the plant as well as the insects?

Please excuse what may appear to be a catalogue of incompetence, but if you are able to offer some life-saving advice at this point, we would be eternally grateful.

Answer
Hi Mike,

It is very difficult to get citrus tree to bear fruit when they are kept indoors in the colder months. Retailers never tell you that because they want to promote sales. Four fruitings a year might be possible when they are grown outdoors in semitropical climates!

The problem is that Citrus trees are sun-lovers and even sunny indoor light is not really intense enough for Citrus trees to flourish. In addition, these trees prefer cooler night time winter temps in 45-60 degree F. range and that is colder than most of us keep our homes.

The scale infestation is a pretty good indication that your tree is under stress for other reasons - usually improper light or watering. You may correct the scale problem, but the underlying stressor will remain. Oil sprays work well outdoors, but not so well indoors. I recommend a thorough drenching of all leaf and stem surfaces with a solution of 5 parts water, 1 part isopropyl alcohol and a squirt of liquid dish soap.

Prune off any dead or brittle stems and branches as they will not recover. Regular pruning is a good idea anyway.

Make sure you are not inadvertently over watering when your Citrus is indoors where light and water use are both reduced.

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

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Will Creed, Interior Landscaper
Horticultural Help, NYC

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