When I began to transplant into the strawberry jars I discovered that the root systems on the alyssum were really small. They lost almost all of the dirt around their roots when I took them out of their flats. But I persisted and managed to get about half in the strawberry jars. The rest have been put in various pots around the back yard.
At first I was very disappointed with their appearance but they are now filling out and spilling over the rims of the jars.