This is crazy cute. Take a pot - paint with chalkboard paint (or even just plain old black paint)... paint the rim yellow... add the lines / numbers (maybe with a sharpie?) and pop a pretty plant inside. When doing for the whole class, say "Thank you for helping us grow" LOVE!
Green is for the inspiration you give me each day. Blue is for your patience in showing me the way. Orange is for your warmth and caring style. Yellow is for the way you always make me smile. Red is for my life that you have touched this year. You're a very special friend and I love you dear. You're a "Magnificent" & "Marvelous" friend.