Citrus plants are generally planted out in Spring after the threat of the last heavy frost has passed.  They like a sunny but sheltered spot, such as the North side of a house South side in the Northern hemisphere.  Having large shrubs or small trees either side of your tree will also have a useful sheltering affect. 

Citrus trees also require light well drained soil to thrive, so unless you have very well drained sandy soil the best method is to plant them on top of the ground.

A. Dig out a shallow hollow about ten centimetres deep and one to one and a half metre wide.

B. Fill the hollow with a mixture of Sand and manure cow ,horse or sheep. You can also add some compost if you have it.

C. Soak the plant in it's pot in a bucket of water for about an hour before you plant it out.  Remove it from the pot, tease out it's pot bound  roots and place it at the centre of the hollow that has been filled with the sand and manure  mixture. 

D.  Use  the excavated soil from the hollow, plus more sand, manure, and compost and more soil if needed and mound it around the tree to the level of the base of the trunk.

E.    Place a small amount of sand around the base of the trunk to reduce the risk of collar rot, which can occur if you run mulch right up to the trunk.  Cover the rest of the mound with straw mulch.  Give the mound a thorough watering to ensure that the roots are not exposed to any air pockets.

Post Planting Care.
Water the tree regularly for at least six weeks after planting.  Citrus trees are shallow rooted, so try not to cultivate the ground under the tree. 

Possible Problems
Two of trees in the author's garden developed a lean which was possibly due to them being planted on mounds.  So it might be a good idea to stake the tree for extra support during the first couple of years.

If you have really heavy clay soil there is a risk that by digging a hole see A. and filling it with sand and manure you may create a hole that will become waterlogged in wet weather.  This is because heavy clay soils are not very porous, so water will tend to run off the clay until it reaches something more porous,  like the sand in your hole.  If you have very heavy clay soil then it might be wise to bypass the digging of a hole see A. and simply place the plant on top of the existing ground.

If your soil is waterlogged for much of the year then simply placing your citrus tree on a mound may not be enough.  You might have to lay agricultural drainage pipes to help drain the water away.




SOURCE REFERENCE MATERIAL
Growing Fruit in Australia  by Paul Baxter and Glen Tankard  ISBN 0 17 006915 X