[Arid_gardener] Question from Home-Hort WWW page

[AZamigo@aol.com]

I am going to plant a Lisbon lemon the second week of March in Tucson.  I am probably going to put in a 5 gallon plant due to easier installation and a shorter transplant shock period.  How much larger should the hole be than the container.  My soil is not the best-caliche, but the grapefruit tree planted in July of 1999 is fruited well last year and is slowly gaining frost resistance.  It was planted by a landscaper as a 15 gallon, so its shock period was longer.  How should the backfill be ammended?  Is sour orange still the prefered rootstock for the low desert?  Thanks for all your help.