Anyone have success growing hidcote lavender?

Howdy, I’m from Dallas but have learned so much from this specific subreddit and the climates are close enough, I thought I’d ask.

We just bought a half acre plot in Dallas, Tx and I wanted to focus more on plants that will survive some of the wild winters we’ve had.

I’ve been running a lavender experiment to test various types with an emphasis on hidcote given its cold tolerance.

All of the lavender varieties, including other English lavenders like munstead are thriving in this heat except the hidcote.

I planted all in my loam bonsai mix consisting of sand, compost, perlite, vermiculite, and decomposed granite. They’re all watered via drip irrigation, once a week, to prevent any water from getting on their leaves. I mulched with a thin layer of lava rock as I heard it speeds up water leaf moisture as well. They also get 8 hours of sun.

I can’t for the life of me figure out how to keep these hidcotes alive. I know our heat can smoke them but I didn’t think it would be this bad.

Is there any way to definitely know when to water?

It’s been two weeks since I watered the hidcotes and I noticed some of their centers droop and soil meter registered near dry substrate 2” below the topsoil. This lead me to water earlier this morning and the drooping has only gotten worse in the last two days. I’m unsure how to navigate the watering here.

I know people have grown hidcote successfully here and mine in partial shade are kind of doing okay so maybe it’s too much direct sun given our heat? Maybe you have to get hidcotes in early to establish well enough before the heat?

I might add a shade cloth to see if it helps. Navigating watering has proven difficult.