Soil testing to prepare for citrus plants is an important step in growing healthy, fruit-bearing trees. This step may not be necessary for many fruits and vegetable grown in a home garden, but it's very important to have the proper soil pH level and density for growing citrus plants.
Citrus Soil Depth and Drainage
The soil needed to grow citrus trees is deep and well-drained. If there are a number of trees in the area, then the soil is probably sufficiently deep to sustain citrus plants. But citrus trees require good drainage around the roots and on the surface. If there are rain puddles surrounding the base of the plant, drainage is insufficient.
A soil that's got a lot of organic material in it, such as peat, is typically a well-draining soil. This lets water run down the soil and avoid pooling around the roots, which can cause them to rot. To make sure that the soil drains well enough, you can dig a post-hole that’s 3 or 4 feet deep. Fill the hole with water and monitor the drainage. All the water should be drained from the hole within 36 hours. If there's still water in the hole 48 hours later, the soil does not drain well enough for citrus plants.
Soil pH Level
Citrus plants do best with a pH level between 6 and 8. If the number is above 8 then the soil is too alkaline and not good for growing citrus trees. Elemental sulfur can help bring the number down if it's just a little above 8. Chelated iron tablets placed in the soil can help lower it as well as adding more nutrients to the soil for the tree to absorb. If the pH level is more than a few points above 8, then the expense of changing and maintaining the level, if it's possible at all, is prohibitive. You may want to put the tree somewhere else instead. If there's a high lime or salt content, the spot is wrong for citrus.
If the pH level is below 6, you can try adding dolomite lime to increase the acidity of the soil.
General Ground Preparation
If you're not starting with an already cultivated spot, then you want to make sure that once you've turned the earth and had the soil pH tested.
You want to remove all grass in a circle around the tree about 4 or 5 feet in diameter. And make sure the hole where you'll plant the tree is in the middle of that circle, about 1 ½ times as wide as the root ball. If you're planting on bare ground, dig the hole the depth of the root ball. If there's grass beyond your tree circle diameter, make the hole about an inch less deep than the root ball.