If you "forgot" to send a greeting, card or gift to someone, it is not "too late".
There is no time limit on holiday hope, holiday cheer, and holiday thoughtfulness. When you share, there is not need to give excuses, rather approach your message, flowers, gifts or event as a New Year's well-wish, or a post holiday pick-me-up.
Sometimes the crunch of the calendar can be stress and forgetfulness, so instead of beating yourself up for that, embrace the opportunity to let someone know you are thinking of him or her.
Go ahead, send the card, write the note, email your thoughts, have flowers delivered! No date is too late, only no day means no sharing!