It happened during one of her practice and sparring sessions outside the territory, assisted and guarded by her husband. This was something they did at least once a week.
She was just practicing her vine control at first, which was one of the go-to skills of wood users during battles. After all, it could control or inhibit the movement of enemies, which was extremely useful.
The strength of the hold, however, still depended on the plant itself. While wood users could temporarily increase their durability, it was only by a percentage, so there were plenty of limits.
After some practice, she had the inspiration to mix the good parts of the aggressive skills and the support skills. The aggressive skill focused on controlling plants to attack, while the support skills focused on the integral enhancement of the plants themselves.