No.
At least, not necessarily.
Of all the many novenas I have prayed to my beloved Therese over the years, only one, I think was ever affirmed with a literal, physical rose. Most of the rest were answered with “roses” far better - blessings, graces, spiritual favors, etc. One recent such occasion involved, not a real flower, but rather someone giving me a book entitled “A Rose From Heaven”.
I warmly discourage the offering of novenas to Saint Therese practiced with an expectation of receiving a real flower, or any material sign at all - and my Carmelite Order likely concurs - for it borders on superstition and vain, credulous devotion. Now if a real flower is what you *really * need, then she’ll send you one, be sure of it. Otherwise, it’s best rather to seek for affirmations of authentic spiritual value…