Wild Ginger, How Vigorous Is It?

How vigorous is wild ginger? How rapidly would a few plants spread over a narrow 3 feet wide, shrub and tree covered area? How many plants should I start with?

Wild Ginger increases slowly in size of clump if the conditions are right.It likes woodland conditions with dappled deciduous tree shade. Soil should be well-drained but moist.
I would suggest that you start with plants on 1 foot centers. In three to 5 years they should have filled in the area. They never form a really inpenetrable carpet.