Evergreen trees present a problem because the needles they drop tend to suffocate moss. Soil is the next important consideration. Mosses generally prefer acidic soil with pH levels of 6.0, 5.5, or lower, in which New England is rich. Kits for testing pH levels are available at garden centers, but professional soil testing labs are preferable. Be sure to take samples from different parts of your yard to assure accurate readings.
Mosses love to be kept moist, but too much moisture without any sunlight can cause mold.
Don't forget to consider, too, how much traffic your moss will have to endure. Moss can provide an expanse of mowing-free green in a yard or a pincushion of emerald, celadon, or burgundy in a rock garden. Of the countless varieties of mosses, only a few are hardy in this growing region, and each provides particular characteristics that can serve different gardeners and different gardens. Cook recommends Plagiomnium cuspidatum . It grows well with other mosses, she says, and provides relatively fast coverage in shade to dappled-light conditions.