I would think that your tree doesn't need fertilizer in winter. Don't know how bad your freezes can be but you want the tree to slow down or stop growing all together prior to any potentially damaging freeze. During cool or cold weather I cut way back on water and don't fertilize at all.

The fact that your tree isn't responding to fertilizer like it would during warm weather is an indication that you should cut back.

The Fruitnut

Hi and welcome here..

Based on what you said,

"Winters are quite mild"

"I tranplanted from the Four Winds nursery container to a Tapla Mix in to a slightly larger pot. The tree was not overly root bound".

Here is what I suggest..:-)

Continue to fertilize at a lower dose than you are doing at "every" watering, 1/4 teaspoon per gallon of water, and don't forget to use vinegar...
A continual feed at such a low rate will continue the balance of nutrients to your tree through the warmer spells,when your plant needs it, and not over burden it.Everytime the soils warms above 55 degrees, the roots are looking for nutrients, NO nutrients, therefore the yellowing leaves.

Fruitnut is right. When roots due get cold, as in below 55 degrees on a consistant basis, day and night, they stop looking for nourishment. But when they awake, the tree is hungry and you should have something there in the soiless mix that we are using for the taking..:-)..

A weakend plant due to improper fertilizing also invites pests.

If you are using Al's mix, which I do, the unused fertilizer will just be flushed out and never over burden your plants anyway. There is also no build of salts...

There is a constant supply of nutrients in winter to ALL citrus in ground from organic matter readily available when the trees decide they need to feed. Soil is alive.

If you withhold all together, you will be looking at nothing more than non-nutrative mix..

Hope this helps...If you need proof of this suggestion, I can provide the pics...:-)

Thanks very much for the responses, Fruitnut and MeyerMike.

You comments tend to track my thoughts on the subject. It's been below 35 degrees past couple nights and not much above 50 degrees during the day, too.

Mike-Thanks for the offer for the pics but I have been viewing your posts for the past year! :) Very cool and inspirational. Healthy citrus are so beautiful!

As we have suggested, your trees will not take up nutrients at all, once the roots are too cold to do so..The reverse can happen too. When the roots get to warm....My plants turned a horrible yellow when the temps exceeded 90 degrees 2 years ago and never dipped below 70 for two weeks..Then the entire month of July, they were anything but a healthy green.

So as you can see, when roots are impaired, either from root rot, over-watering, too cold, or too hot of temps at the root level, they suffer and you almost always see the side effects within days of mal-nourishment.

If fertilzer is in your soiless mix, a rapid onset of green is in the works if there is some fertilizer still available in the mix, as soon as the roots function again properly..

But regardless, growing in Al's mixes as we do, it will do no harm, and will actually benefit your trees when the roots decide to wake up from their rest..;-)

Mike..:-)

Keith,

One more thing..

Thanks for noticing all of our pics and information here..It is really nice to see a lurker come out and participate, and benefit from what is said here..It is great to see many here succeed and find pleasure in growing these remarkable plants!

It makes for a much better forum..

Mike..