Also, since they're long-lived perennials that *want* to grow into a 4-5' shrub, the bigger a pot you can give them, the happier they'll be. Keep em in a small pot & they end up wanting to give up.
The less top-watering the better, probably.
Once the initial seedling is 6", cut it back to 4" even if it seems excessive, and keep on that "program".