The flowerbeds that I would plant it in either have weeds (that I haven't gotten control of) or have wood mulch on top of the soil. It's just faster and easier to pot it up into a container and remember to add pea gravel as the mulch.
Don't want to add wood mulch, as I accidentally did last year, as I lost 2 Agastache 'Morello' plants. Agastaches, not only do they like well drained (or very well draining) soil, they like to have their feet (roots) dry in the winter. The Morello's didn't even last til our winter. They had enough water long before that.
