First I would like to mention that I am in Arizona. You indicate that your zone is 9
so I am interpreting the weather patterns to be similar with ours here. I do grow all
of the mentioned plants. ;-] 'Healthy' plants can take transitions quite well. Grapefruit,
Oranges, and Lemons may loose leaves during the cool period if the temp does dip
under 20 more than a week or so but they will quickly recover soon as the weather
warms up. If you are worried simply relocate them to a sheltered location such as
under the patio, carport or house eves. Often it can be effective to throw burlap
over them to protect during those very cold nights. A few of my Pomegranate are
in Bonsai containers and they stay out doors without protection. Apple I started
from seed back in 1995, trained as bonsai, handle the colder conditions and grow
outside year around. Allow them the chance to adept to the natural environment
and you will simply be amazed!

Mean while be sure to properly fertilizer and well water with each and every watering
time. Sprinkle a pinch of Epsom salt a few times with watering for the month of October
to help easy the weather transition. All and all, year around proper culturing gives any
plant the best survival rate than any thing you do at any certain time of the year.

Ankrara's Hobby Corner

Wow, thank you very much for the Insight.
Yes, I am in the California High Desert, so my Weather is Much more like Arizona, than California. Although I think we might be a bit drier. (We do not get as nice of a Monsoon flow here.

In Fact I use the Arizona Master Gardener site as my Bible.
http://ag.arizona.edu/pubs/garden/mg/index.html

I do have a spot that is Sheltered on three sides, (and it is near my Clothes dryer exhaust vent) That I will probably put the Citrus in for that Extra degree of protection.

Our Winter Temps Mostly stay over 30, with some dips down to 25 or so, I think we hit 20 for about 30 minutes last winter. (I love my Weather station for historical reports). But it is common for us to go a week without it getting over 45 degrees. (The Apple trees just love those chill hours)

Since these plants are in Pots, do you think I should build up a Layer of Straw or Dirt around the Pots for Extra Insulation? (I heard that potted plants will chill faster than those in the ground)
(It is so weird talking about this as I contemplate spending the rest of the afternoon in the kiddie pool to cool off ;))

Here is a link that might be useful: Arizona Master Gardener Manual

An old sheet if the plants are strong enough to hold it up, or floating row cover, will hold heat from the soil underneath and can save plants. Sinking pots to the rim in soil will protect roots from constant temp swings in winter.

Here is a link that might be useful: Floating row cover