The first 12 to 18 months are the most critical in a citrus tree's life. How and where trees are planted and then cared for is extremely important.
Since March and April are the two best months to plant citrus, here are some tips from Don Durling. He's the third generation to run Durling Nursery in Fallbrook, the wholesale grower of many citrus trees found at nurseries.
Through the years, they've refined the planting and care of new citrus to, if not a science, a set of good rules.
1) Choose a spot in full sun that is out of the wind but not in a lawn or a frequently watered garden bed.
2) Make sure the soil drains quickly. To find out if it does, dig the planting hole 10% shorter than the height of the root ball several days before planting.
Fill it with 12 inches of water, let it drain away, then fill it again. This second 12 inches of water should drain away in less than six hours. If it doesn't, you're going to have troubles growing citrus.
Either have French drains installed (not a job for a homeowner), dig gravel-filled drainage holes to either side of the planting hole (less successful) or try another spot.
3) If the location is OK, cut away the can (with tin snips or a knife) and gently place the root ball in the hole. Use a board laid across the surface of the soil to make sure the top of the root ball is about an inch higher than the surrounding soil.
4) Begin filling the hole with native, unamended soil until you are about 12 inches from the top. Add slow-release fertilizer pellets to this native soil if you wish.
Fill the upper 12 inches with amended soil, to which you have added about one-third organic matter, the kind sold at nurseries in bags as "planting mixes" (don't use manure). Premix the soil and the amendment in a pile or wheelbarrow.
5) Use the remaining soil mix to build a several-inch-high, circular irrigation berm around the root ball. Make this watering berm or basin no larger than the root ball, or irrigations may wet the soil around the plant but not the root ball.
6) To reduce transplant shock, remove most of the fruit from trees.
7) It's very important for the first 12 to 18 months to keep new citrus watered. Don't drown them, but water as often as necessary to keep the root ball moist. This may mean watering every three or four days at first.
To make sure the the root ball is moist, probe the soil with a screwdriver or soil probe.
Lengthen the time between irrigations after about nine months to every seven to 14 days. After 18 months, deeply water trees every 10 to 12 days, or as seldom as once or twice a month.
Of course, how often you water will depend on the weather, how hot or dry your area is, and your soil type. When the tree is young, be especially careful to keep trees watered during Santa Anas.
8) Begin fertilizing right away (nursery plants have been on a constant-feed program). If you did not add slow-release fertilizers to the planting hole, dig them into the top few inches of soil, or fertilize lightly every month for the first year or two, then switch to every other month when it is 2 years old and finally, when the tree is about 6 feet tall, to twice a year (in February and June).
9) In hot areas, if the trunk's bark is exposed to the sun, paint it with flat-white, non-enamel, water-based interior wall paint. Thin it by half with water. The hot sun can kill the cambium layer beneath the bark on unprotected young trees.