Ask Mr. Smarty Plants

When a native plant like Melampodium leucanthum (plains blackfoot) suddenly begins to suffer, you have to ask yourself what in the environment has changed to cause this problem? Here are the Growing Conditions for blackfoot daisy, which is definitely native to Central Texas:

Water Use: Low
Light Requirement: Sun , Part Shade
Soil Moisture: Dry
Soil pH: Acidic (pH<6.8)
Soil Description: Dry, rocky, calcareous soils. Rocky, Gravelly Sandy, Limestone-based, Caliche type
Conditions Comments: Blackfoot daisy is a sturdy, mounding plant, that will flourish in rock gardens. It is heat and drought tolerant. Good drainage is essential to its success. In late winter, older plants can be cut back halfway to keep them compact. Rich soil and abundant water will likely produce many more flowers in the short-term, but may consequently shorten the lifespan.

The things that jump out at us are the low water requirement, the need for good drainage and the preference for acidic soil. The soil in Central Texas is generally pretty alkaline, but your plants have been okay with that up to now. Goodness knows, we have had low rainwater for the last two years, and apparently the plant was good with that. It looks as though the drainage is the key. As long as we had no rain and you were watering responsibly, the blackfoot daisy was okay. Now, there is rainwater, which you can't turn on and off, and  water is likely standing on the roots of the plant. The best solution for that is to amend the soil with compost or some other organic material, which will improve the drainage. You will notice from the preferred soils for this plant that they are all good at draining. Possibly the soil in your garden is clay, or clay-based, which doesn't drain well at all. If you're up for it, you could even try taking some plants out, and quickly work compost into the soil, returning the plants before the roots have time to dry out. We can't say if this will save your present plants. We would recommend trimming off the upper 1/4 to 1/3 of the affected plants (after you return them to the soil, if you decide to go that route), treating them as though they had transplant shock. As we go toward winter, perhaps getting more rain, the plants will all go into semi-dormancy or even die back to the roots, to re-emerge in the spring. Even if you lose those daisies now, you will have improved the long-range vitality of your garden. And, the level of acidity should be changed by the addition of organic materials.

From our Native Plant Image Gallery:

Melampodium leucanthum

Melampodium leucanthum