Not invasive and not a rampant spreader. I've never seen it reseed freely here. Looks best in rock gardens, where it creeps or drapes nicely over the edge or can be used as a border plant. Needs very well drained soils and full sun. In most winters it will be evergreen but can be sheared back lightly in early spring to 'clean' up. I find it can be used in much the same way as the much more commonplace Lithodora and prefers similar growing conditions. And the hummingbirds love it.

Except not so hot and dry for Lithodora.

Thanks for your always knowledgeable replies.

I'm relieved that it's going to be okay because the plants are already on the way!

However, I hope I have more luck with them than I have had with lithodora. I've been successful with most plants, but lithodora isn't one of them. They get black in winter. Maybe the soil is too wet? What would I do to improve drainage? Gravel mixed in or on top? I'm thinking about the zauschneria right now, but this may apply to the lithodora too.

I regularly work compost into the ground.

This problem is common here. Try being sure plants are in full sun.

Compost may increase the moisture retention of the soil. Too wet winter soils is most often the problem with Lithodora blackening or dying out in the center over winter, but cutting it back in early spring will very often rejuvenate the plant.

Mounding the planting area slightly or substituting a barkier soil amendment (often sold as soil 'conditioners') should help with drainage. Zauschneria is often recommended as an alpine or rock garden plant so you might want to research amending your soils to achieve that desired condition. Traditionally, alpine or rock gardens share very sharp drainage with somewhat gravely, lean soil conditions - little, if any, additions of organic matter.

Bark, compost etc. decompose, leaving the soil to return to its original condition unless the plants are dug up and the bed is re-amended.

Mineral materials like sand will not decompose, but a given soil may need yards of it to be added before the texture changes enough to suit a particular plant.

Buying a soil known to be suitable and dumping it on top, planting in that without mixing it with the existing soil is most to the point.

Where a mound or berm cannot be accommodated the existing soil can be dug out and replaced with the imported material. However, if the soil already on the site is too heavy and the new bed too small, a sump-like condition may be produced - same as with a small amended planting hole dug out of a damp soil.