When do vegetative propagules begin to form in herbaceous perennials?

Vegetative propagules in herbaceous perennials typically begin to form after the plants have reached a certain level of maturity, which is closely associated with their leaf development. Once a herbaceous perennial expands past five leaves, it indicates that the plant has established enough foliage to support the growth of additional structures, including vegetative propagules. This leaf development facilitates photosynthesis, providing the necessary energy for the plant to produce new growth.

Roots play an important role in the establishment of a plant, but the formation of vegetative propagules is more directly connected to leaf development and overall plant maturity. While reaching a specific height or the number of flowers can indicate growth progress, the critical factor in the development of vegetative propagules is generally tied to the plant's ability to produce and sustain adequate foliage. Thus, the formation of propagules is best aligned with the state of leaf expansion rather than other factors such as flower count or height.