A reader writes "I bought 2 citrus trees in October. One is a tangelo & the other a lemon. The lemon has fruits on it now and the tangelo is blooming. I would like to grow these in large pots rather than putting them in the ground. The nursery where I bought them told me I should repot in March (which is now) and I can put them in a large pot and they will grow very well. What is your opinion?"
Sure, you can repot now. You do not have to be as careful when repotting citrus as you do with many other plants. Most plants produce a root system that have a mass of fine delicate root hairs which are the plants main feeder roots. These normally develop at the last 1/2 to 1” of each root. They are extremely delicate and easily damaged when transplanting. Fortunately, citrus do not produce a feeder root system based on root hairs. Citrus roots absorb most of their water and nutrients from the last couple inches of the roots themselves. Very little absorption occurs in the older woody portion of citrus roots. Because, citrus do not have root hairs, it is much easier to transplant without causing any major damage. This does not mean that caution and care should not be exerted. I would use my fingers and scratch off all the way around the root ball to loosen the soil so 1/4 inch of the root ends are free, then plant the tree in a fast draining growth medium (for example, the Adenium mix). I would be somewhat careful, but do not worry much about the little damage that might result. Just use a little caution.
As the initial root ball will be more compact then the new growth medium, water will tend to run off the original root ball and instead pass through the new growth medium. Therefore, for the first month or two, you should have saucers under the pots to insure that the entire root system is watered (water will also be absorbed from the bottom up). After the 2 months – take the saucers away! The pots need to freely drain or your trees will experience root rot. When citrus roots are growing in a fast draining medium with good air porosity, they produce rapid growth. Do expect some leaf drop and maybe even the loss of the fruit and blooms as your plants grumble their displeasure, but they will perk up. Monitor your pots and water when the top inch of potting soil becomes dry to the touch.
I am not in any way associated with easyBloom, but I tested one of their PlantSmart Digital Plant Care Sensors and am suggesting you might want to purchase one to help monitor your plants. You can read about them at http://www.easybloom.com/.