How to Take Care of a New Citrus Tree in the Ground
If you want to plant your citrus plant in the ground, be sure and wait until after the last chance of a freeze. If you keep it in the original pot for six months, take it out after that time by laying it on its side and mashing the plastic gently to loosen it from its sides. Then pull the ball out of the pot and examine to see if it is root-bound. If root-bound either put it in the ground or in the next size larger pot and fill void with composted pine bark or good potting soil. Potting soil for Azaleas is good (containing peat moss and or pine bark mulch).
Planting in the ground: Plant in a sunny location, preferably south of a brick or stone wall, where it will get some radiation from the wall and protection from the winter north winds. For best results plant in good loose fertile soil. If you have hard gumbo soil, till in some sharp sand (sand that is used to make concrete) to loosen it up. Soil of a pH of about 6 to 6.5 is best. You can lower the pH by adding pine bark mulch, or you can increase the pH by adding lime (vary rarely do you need to add lime). Be sure your hole drains water in less than a day or you need to plant in a raised bed. I mix in a little composted pine bark mulch with the soil. Plant the ball slightly higher that level with the soil line because when you water in to remove air pockets the soil will settle somewhat. But be sure all roots are covered with soil. Do not put fertilizer in the hole and never use fertilizer stakes.
Fertilizer: Fertilize your citrus tree each month during the growing season, which is March - June with a high nitrogen fertilizer. At least once a year fertilize your tree with a fertilizer that has trace elements that are high in Iron, and Zinc, and includes Magnesium and Molybdenum. Turf magic's "Premium Fruit Citrus & Pecan Food" 16-7-5 (PFC&PF) is good but a little low in Zinc (0.05%). Sta-Green's 3 month "Azalea Camellia & Rhododendron Food" 14-7-7, 14 lb bag is almost the same as PFC&PF, but has 1% Iron instead of the 2% in PFC&PF. Both of these can be purchased at Lowes. Scotts' "Citrus Food" 18-5-18 time-release fertilizer is a little harder to find and comes in 2.5 lb boxes. It includes 0.5% Iron, 0.25% Zinc, and 1.0% Magnesium. I have published a formula that was put together by Texas A&M for calculating the amount of fertilizer to use each year based on the plant's age and strength of fertilizer. It is located in the bottom of this section of my web page. If you have a serious Iron deficiency you can apply Copperas (Ferrous Sulphate). Follow the directions on the bag.
Most of my trees are grafted on trifoliate or carrizo citrange rootstock. Pinch or cut off any new growth that forms below the graft on the grafted trees. The trifoliate grafted trees will eventually grow to be about eight to ten feet tall and eight to ten feet in diameter, so set apart knowing they will get that big. The ones grafted onto carrizo will get slightly taller and bigger plus they grow faster. The seedlings are unpredictable and could get much larger. Do not plant your lime tree in the ground because it is the tenderest of all the citrus to freezes. Trifoliata rootstock does not like sodium which can come from watering with water containing minerals or traces of salt (sodium chloride). Water from a water softner could contain sodium. You can decrease the sodium in your soil by adding gypsum. It will replace the sodium with calcium.
Citrus Leaf Miner: Should your tree get curly leaves with brown veins going in all directions though the leaves, you probably have the Citrus Leaf Miner (CLM) eating your leaves. It is a tiny moth that lays her eggs at night on the bottom of the leaf. The larva hatches out and burrows just under the epidermis (skin) of the leaf. Once it is inside the leaf it can not be killed except by systemic insecticides. Sprays that will kill CLM are: "Tree & Shrub Insect Control (T&SIC)", by Bayer, "Lawn and Garden Spray with Spinosad, "Conserve SC" (best buy, buy it on ebay), "Agri-Mek", "Admire Pro", "Provado 1.6F", "Confirm 2F", and "Prodigy". "T&SIC, Provado 1.6F, and Admire Pro" are systemic and are the best for nonfruiting,. Dormant Oil slows them down, but be careful not to burn the citrus leaves with the oil in the summer. All the sprays mentioned are commercial sprays and are hard to get except for T&SIC, Spinosad, and Dormant Oil. Follow the directions on the bottle on how to apply. Click on my link citrus leaf miner for more details.