Could be something leaking from the car that was there - gas, oil, antifreeze

It actually is a south facing wall and the sunlight does not seem to be an issue.

ltitlon, you're scaring the hell out of me with that talk!

I will see what the pH test says. Any reason why the pH would be different in sections of a garden, especially with freshly laid soil as of last year?

It could help be more specific if you tell us just how much of the soil is "freshly laid."

Is it under a drip line? What is the drainage from the garage roof, and what is the roof made of? Things there might be getting smashed with downfall that the lilies could handle because of their rhizome, foliage cushion. Is that possible?

In times past I constructed raised beds out of treated wood, there was never an issue with plants growing.
Ltilton had a good idea re oil etc.
Also there may have been past herbicide use. One herbicide, for instance, Pramitol, is supposed to stop growth for a year or more.

Thanks y'all. The garage has standard tar roof shingles. There is at least 1.5 feet deep of new soil. It was 3 feet when dumped, but has now packed down. I basically dug 6-8 inches of gravelly clay out and removed it before adding the new soil last summer. There was no pesticide use that I could tell (by the rampant growth of lilies in that spot).

glorygrown: I think you get the prize. I climbed up there and I think what is happening is that rain water is somehow getting behind the eaves and running down the wall, so it was not noticeable by just looking at it last year. Looking at the thaw now, it looks like a lot of water gets back there and pools up.

Gonna try and seal the eaves tight so that doesn't happen.

Thanks everyone.

Get the soil tested, too, if you can.

You'd be better off getting a soil test done at your local agricultural center. Yes, your soil will be different ph's in different spots. When you take the soil test you will be taking little samples from all over the garden. It only cost about 3 dollars for just the ph test and 7 dollars for a test that will tell you what you need to fertilize with.

Hey all, just a follow up... I tested the pH throughout the garden, in the "dead zone" the pH was acidic as hell! Like, under 5. Everywhere else was ok (b/t 6.5 and 7).

Thanks to all, I think the mystery is solved.

Plant blueberries!

You might want to try a organic soil stimulator as well.