Q. Is it too early to plant rosemary in the ground?
Rosemary likes heat and well drained soil. I think neither exist now where you live. I would keep the Rosemary on your sunniest window sill until we start having some warm weather. I suspect Rosemary will not winter over where you live (it doesn’t winter over reliably here!) so bring the plants in their pots in for next winter. For now, keep them cozy on your sunny window sill and then when it is warm, edge them into full sun. The plants have to adjust to full sun (they sun burn like we do) so move them out slowly.