It mainly grows in shallow water and is either rooted or floating on the water surface. It also interferes with navigation andÂ can grow fromÂ the water's edge to depths up to 10 feet. Hygrophila Willow is another great Hygro plant for beginners. Prefers fresh water with a pH between 7.0 -7.4. Hygrophila. Hygrophila corymbosa is a fast-growing plant that can be frequently trimmed back. Some people prefer not to introduce Hygrophila polysperma into their tanks as it can rapidly grow out of control, taking light and nutrients away from more other plants. An isolated leaf will often root itself.