when to plant?

[McClements, Jim]

Diana

You asked about arisaemas and trilliums, when to plant. The answer is
somewhat different for the two, since arisaema tubers grow new roots every
season, whereas trillium roots are more or less permanent and start their
main growth cycle in late summer.

This means that trilliums will do much better if planted in late summer or
early fall.

Arisaemas can be planted either time. There may be some slight advantage in
fall planting, so that roots can start growing in very early spring, but this
may be overshadowed by the danger of tubers rotting during a wet winter in
inadequate drainage, or by having a species that might not be winter hardy in
your climate. if you are talking about the native A. triphyllum, fall
planting should be fine.

Jim McClements