A handwritten note is always in bloom. Hellos from faraway spots in the summer. Back to school correspondence in the fall. Thank yous following winter fetes. And overdue updates between friends in the spring, all on stationery with garden-inspired good looks.
Thank You Notes should be sent out as soon as possible after you receive the gift. One to two weeks is the sweet spot, as your note should be a thoughtful gesture, not a reminder for what was given.