I was asked why the tree is yellowing, I thought perhaps poor drainage or improper soil, and bad shape. It also stopped flowering.

Hmm, it's got some burnt tips on the leaves which is usually from over-fertilizing. Do you know what they've used to fertilize it? As the weather cools they need to taper back the amount of fertilizer until it would need very little through the winter, unless it's in a warm greenhouse under major supplemental lights. They need all sun, all the time.

If they can order some fertilizer that is citrus-specific that will be the best thing to use. Citrus have specific needs in the way of micronutrients.

The color of those leaves looks pretty good to me other than the burnt tips.

dyzzypyxxy said:Hmm, it's got some burnt tips on the leaves which is usually from over-fertilizing. Do you know what they've used to fertilize it? As the weather cools they need to taper back the amount of fertilizer until it would need very little through the winter, unless it's in a warm greenhouse under major supplemental lights. They need all sun, all the time.

If they can order some fertilizer that is citrus-specific that will be the best thing to use. Citrus have specific needs in the way of micronutrients.

The color of those leaves looks pretty good to me other than the burnt tips.

They were using this

Ok, can you show us the back of the bottle, please Keith? Need to see what's in it besides the N - P - K. How much did they use and how often?

Any idea about how much water they're giving the plant, too? When the weather cools, you need to water less, but if then you still fertilize the same amount, the fertilizer is not diluted by water so much, so instead of getting less fertilizer for cooler weather, the plant gets more.

So . . if the plant gets a dose say, once a week through the summer? Then you'd give it the same amount but maybe only every second week, or half strength once a week would also work. Taper off through the fall, until half strength once a month in winter would probably be enough - again depending on where it's growing in the winter.

dyzzypyxxy said:Ok, can you show us the back of the bottle, please Keith? Need to see what's in it besides the N - P - K. How much did they use and how often?

Any idea about how much water they're giving the plant, too? When the weather cools, you need to water less, but if then you still fertilize the same amount, the fertilizer is not diluted by water so much, so instead of getting less fertilizer for cooler weather, the plant gets more.

So . . if the plant gets a dose say, once a week through the summer? Then you'd give it the same amount but maybe only every second week, or half strength once a week would also work. Taper off through the fall, until half strength once a month in winter would probably be enough - again depending on where it's growing in the winter.

I can't get a photo of the back, but they said they fertilize once a month but water sparingly, perhaps this isn't diluting the fertilizer?

That could be it, Keith. I'd advise not to fertilize again until the leaves stop burning at the tips. Maybe miss one month, or give half the amount next time.

I found it online, and it's a liquid fert that you dilute at a tablespoon per gallon. Trouble is, growing a fruit tree indoors is really a lot different than growing a house plant. You can't just keep giving it the same thing all year round when you have it outdoors for half the year, then indoors.

dyzzypyxxy said:That could be it, Keith. I'd advise not to fertilize again until the leaves stop burning at the tips. Maybe miss one month, or give half the amount next time.

I found it online, and it's a liquid fert that you dilute at a tablespoon per gallon. Trouble is, growing a fruit tree indoors is really a lot different than growing a house plant. You can't just keep giving it the same thing all year round when you have it outdoors for half the year, then indoors.

What about bugs? My friend said it gets white bugs during winter when it's brought indoors and wants to know a natural pesticide to use, any thoughts?

Soapy water is always a good preventative - 1/2tsp. to a quart spray bottle of water, and spray the whole plant including the undersides of the leaves and the soil surface before they bring it in the house. The rinse it off with plain water after a little while. If the white bugs show up after that, treat again the same way, and rinse the plant in the kitchen sink or the shower.

They should do this to all the plants that were outside for summer, before bringing them indoors.

My friend told me she's been watering once a week and fertilizing once a week! I told her she's over fertilizing and to cut back and fertilize every month or two as the tree is quite small. And to water only when soil starts to dry out.
She has been using regular soil for it and I suggest soil for citrus plants and she will now use that.

My last advice was completely change soil before moving indoors to prevent bugs from being moved insure, my friend said everything I mentioned makes sense and she thinks this will fix the issues.

Keith, I wouldn't advise changing out the soil. Citrus have very fine feeder roots and the damage you'll do if you change out the soil will very likely kill the plant.

Just flush the soil with the soapy water solution before she brings it indoors. Soap kills off a lot of bugs. You can also flush with diluted peroxide if you're still worried - buy a bottle of it at the drug store, and dilute 1oz. of that with 32 oz. of water. Water that right through the potting soil and pour it away.

Yes, she's definitely over-fertlizing - the bottle of fert says once a month. It's a little tree, but a pretty big plant all the same so she needs to keep watering to keep it moist. They don't like to dry out. It shouldn't sit in water, but once the top half inch or so of soil dries she should water thoroughly again - enough so that water flows out the bottom of the pot. Tell her to stick her finger in the soil to test for dryness.