 Trillium grandiflorum favors well @-@ drained , neutral to slightly acid soils , usually in second- or young @-@ growth forests . In the Northern parts of its range it shows an affinity for maple or beech forests , but has also been known to spread into nearby open areas . Depending on geographical factors , it flowers from late April to early June , just after T. erectum . Like many forest perennials , T. grandiflorum is a slow growing plant . Its seeds require double dormancy , meaning they normally take at least two years to fully germinate . Like most species of Trillium , flowering age is determined largely by the surface of the leaf and volume of the rhizome the plant has reached instead of age alone . Because growth is very slow in nature , T. grandiflorum typically requires seven to ten years in optimal conditions to reach flowering size , which corresponds to a minimum of 36 cm2 ( 5 @.@ 6 sq in ) of leaf surface area and 2 @.@ 5 cm3 ( 0 @.@ 15 cu in ) of rhizome volume . In cultivation , however , wide disparity of flowering ages are observed . 
