No on the avocado. Doubtful on the grapefruit. HOWEVER, there are a number of hardier citrus that may do OK in Dallas. Check out some of the mandarins (Satsuma, Changsha etc.) and some of the hardy hybrid citrus such as Citrandarin, Citrumelo, Orangequat, Citrangequat, Citrange, etc.). Also, you should be aware that any citrus grown from seed may take many, many years before they are mature enough to bloom and bear. If you trim them down, they may never bear. So, unless you are young, you might want to invest in a grafted tree that is capable of bearing fruit within a year or so! Unless you are happy to grow it only for the foliage. See link below. (I do not know whether they can ship to Texas, so you may need to find a Texas grower). Here is a link that might be useful: Here's a place to get started

Joann, we would love to see pictures of your cypress trees! also, if i am correct, the upper elevations can be slightly warmer during cold snaps for two reasons- the cold wind tends to whip through the valley, while the mountainsides and hillsides are more protected. Secondly, the colder air settles down lower in the valley (slightly). temperatures where we live in bluffdale (near the jordan) are usually a degree cooler. ps, does anyone know how to subscribe to threads, or access my recently viewed/written posts? (as in other forums)

Before you add anything into the soil test the acidity. If it is already acid, you may be able to get it into the right pH. If it isn't acid, the effort to get it into the right range and keep it in the right range may not be feasible.

The only thing they did not talk about was the tolerance for thin limestone and caliche soils that is so common here. I had great luck with tamopan persimmon in down town Austin. I planted it right up against the house with the driveway right there. I used to clamber over the 8' fence and second floor roof to get fruit every other thanksgiving. It grew very narrow and tall in that space which was a good thing because the space demanded it. The natural Gardener has a good display of fruit trees in the spring. It is a seasonal display geared to the good planting time. They will have cold hour times listed for the different areas of Austin since it varies so much and some of the trees are very picky about how many cold hours one has. I too have mostly caliche and thin soils and no water to spare so I have not made the leap into fruit going out here above Hamilton pool. I have heard that one person dug a HUGE hole in Deer Creek ( rangy uplands soil) and planted a peach and had good luck. The water to water out here is hard as nails too unless you have a huge rainwater tank.