There are a number of alpine or miniature plants that will self-sow in the rock garden. Some are dangerously invasive. I would never have planted so many thymes if I had known they would spread so well by seed! Others, however, seed for a few years and then disappear or have seedlings that are easily removed. One that falls into the second camp is Globularia trichosantha. It forms a small clump of shiny green leaves and the grey-blue flowers nod on short, wiry stalks. It's easy to snip off the dead flowers before they go to seed, but if you forget, you will soon see Globularias in other parts of the rock garden.
