
Here is what I learned.
This is one tough, beautiful and un-thirsty buckwheat, it does not appreciate shade and it's a generous bloomer. The spoon-shaped leaves are sturdy, a nice green and glaucous on the undersides with a slightly waxy feel, perfect for its native salty, windy coastal island where it is dry most of the growing season. However, my plants did just fine in Napa's uncharteristically hard freezes this past winter. They do prefer a lean soil but I have mine planted in a bed that's mostly clay amended with lots of organic matter. So far (just one growing season) they've done great. The mason bees, skippers and hairstreaks love the nectar. I even see the wasps going after it. When the seed heads dry later in the season there will be food for the neighborhood quail. I didn't bother taking a photo of the plants under the maple tree because they didn't perform nearly as well. Those will be replanted in full sun this fall in a roasting, dry-ish bed next to the driveway. It makes a good companion plant for yarrow, Cleveland sage (both of which grow on the Channel Islands) agastache and mullein. The photo was taken before it reached full bloom. It looks even better now, especially with the plants around it having filled in. The plant is full and not unattractive even when not in bloom.
You don't have to live on a windy island to enjoy this plant. My climate in Napa is decidedly Mediterranean, with dry summers and wet winters. Red buckwheat is a winner here.