In this Rows Garden puzzle, the so-called "rows" clues refer to the SW-to-NE slants of the grid. The A "row" holds the answer RHO and all the red bloom clues are 7 letters long and entered into the grid in the shape of a rho (ρ).
The completed Rows Garden puzzle is shown below:
The initials of the regular white and yellow rose clues spells ANSWER'S NOT HERE and ELSEWHERES respectively, indicating that these blooms are not the source of the answer.
The letters extending out of each red rho bloom, in grid order, spell LOUIS DE BOURBON and the initials of the rho clues themselves spell USE HIS WAR ALIAS. This leads to the answer of LE GRAND CONDÉ or LE GRAND CONDE.