Growing Your New Citrus Tree in a Container 

If you should you decide to grow your citrus tree in a container, follow these instructions.

Put your tree in a 3 gallon pot with good light potting soil. Citrus like a soil with a pH of about 6 to 6.5.  You can lower the pH by putting pine bark mulch in your potting soil or purchasing a potting soil that is for azaleas.  If possible, put your tree in full sun, the more the better.  But keep it below 100°F; don’t cook it.  It does best in the backyard, patio, porch, or poolside and not inside during the spring, summer, and fall.  In the winter if it gets too cold and must be taken in, it needs to be next to a window that gets some direct sun or lots of fluorescent light.  Keep it above about 26° F.  Later, if you decide to put it in the ground, wait until all possible freezes are over and in the spring plant in a location protected from the north wind.

Lay it on its side about every 6 months to a year and pull it out of the pot to see if it is root bound. If so, put it in the next size up flowerpot using pine bark mulch to make up for the increased size pot. For example, don’t go from a 3 gal pot to a 10 gal. Go to a 5 gal next. Mine eventually work up to a 15 gal size pot and then I leave them in that size pot for years. You will probably have to put a saucer under the pot on the 10 and 15 gal size trees because the surface area of the leaves really dry the pot out quickly. The saucer will help out and you may get by with watering every few days. But keep the soil moist, not soggy, (or you will get root rot), and let it dry out slightly between watering. If leaves curl like a cigar, you are letting it get too dry. On the grafted trees, pinch or cut off any new growth that forms below the graft. You don’t want the rootstock to produce new limbs.

Since citrus trees are heavy nitrogen feeders, make sure your fertilizer contains more nitrogen (N) than phosphorous (P) or potassium (K).  Use at least a 2-1-1 ratio.  Also, trace minerals like iron, zinc, and manganese are important, so make sure those are included as well.  Ones with high amounts of water soluble iron and zinc are best.  Many all-purpose products will work.  Follow rates on the package carefully as fertilizers come in different strengths, release rates, and application schedules.  You may be able to find specialized citrus/fruit tree fertilizers and they usually have the trace minerals included.  I prefer a time release fertilizer as best, then slow release fertilizers in the granular form as second best and not fertilizer stakes.  Stakes burn the roots near the stake and it doesn't spread out horizontaly very well.  Don’t fertilize if the tree is going to be exposed to cold weather because tender new growth, produced from fertilizing, will get freeze burn first and die.  I do apply a little Osmacote with the higher first number in the winter if the leaves start to yellow.
 
Yellowing leaves indicate lack of fertilizer, lack of trace minerals, or poor drainage.  Dark green, lush leaves with burned tips indicate excessive fertilizing or salt build up from city water.  If burned tips appear, flush out salt or excessive fertilizer by filling the flowerpot with water and letting it drain through the dirt completely.  Burned tip leaves will not green back up, after flushing, but new leaves will not have the burned tips. Gypsum also can be used to remove the sodium.  The sodium will be replaced with calcium from the gypsum.