Ask Mr. Smarty Plants

We really don't have enough clues about the history of your Chilopsis linearis (desert willow), so we'll true to find some that will help you. Is this the first year you have had it, or that it has bloomed?  The blooms appear after summer rains, and in early autumn are replaced by th slender seedpods. According to the USDA Plant Profile on this plant, it is native to the Big Bend area and far west Texas, with a few isolated locations, including Travis County, where the Wildflower Center is, where they are cultivated, also. You are, however, in USDA Hardiness Zone 8a, as is Travis County, so it should be all right there in terms of temperatures, but we don't know about your soils.

Here are some of the Growing Conditions which may also give us some clues:

"Water Use: Low
Light Requirement: Sun
Soil Moisture: Moist , Dry
Drought Tolerance: High
Cold Tolerant: yes
Heat Tolerant: yes
Soil Description: Well-drained limestone soils preferred, but also does well in sands, loams, clays, caliches, granitic, and rocky soils. Minimal organic content the norm.
Conditions Comments: Allow to dry out between waterings, as this will encourage more extensive waves of blooms. Avoid excessive water and fertilizer, as that can lead to overly rapid growth, fewer blooms, and a weaker plant. Prolonged saturation can result in rot. Won't grow as fast or get as large in clay soil but won't suffer there either. Can be drought-deciduous in some regions. Can survive temperatures as low as 10 degrees F."

And under Bloom Information on our page on this plant:

"Bloom Time: Apr , May , Jun , Jul , Aug , Sep
Bloom Notes: Mostly blooms heaviest May to June but will continue to bloom sporadically throughout the warm season after rains."

We looked at a lot of research material on this tree, and got pretty much the same bloom information from all of it, but no average length of time that the blooms remained on the tree. The blooms occur at the tips of branches on new growth, and are fairly fragile. Just theorizing, on the basis of our research, we wonder if perhaps the bloom life you are seeing is normal. If you have no previous experience with the plant, that could be the case.  We would also like to call your attention to the warnings above about over-watering and over-fertilizing. This tree is native to desert washes, in very infertile soil. Too much fertilizer and/or too much water could throw it seriously off balance. And if the tree roots do not have very good drainage, they can rot out. If it is planted in the clay soil that is pretty common in your part of the state, that could well be what is going on. If the area is watered  by a sprinkler system, not only could the tree be getting too much water, but the sprinkler streams could be knocking the flowers off. And, most important, it must be in full sun to bloom well. We consider full sun to be 6 or more hours of sun a day. 

From our Native Plant Image Gallery:

Chilopsis linearis

Chilopsis linearis

Chilopsis linearis

Chilopsis linearis