Well, not that I think that Eve will come in visual range of Victoire's roses. She declared that she was going to scout from way up above to avoid the Zak vs Henry fight and the rose fields are still some tiny drop in the enormous battlefield (furthermore, who never heard of flowers in a cemetery, especially roses?). But Victoire wants to be 100% sure her plans won't get botched this time.

If all else fails, I'm sure that Victoire can kill/incapacitate Eve with a sneak attack. She just would prefer to not raise people's suspicions about her presence there until her roses are big enough that even burning them won't make much of a difference, since they will be able to regen their area fast enough.