There are many areas of New England where people garden in places where there are many trees. Where the trees are tall, even large, open gardens may well be in shade for part of every day. So this list is being constructed with the assumption that many people will have rock gardens containing shade-tolerant or even shade-loving plants. In cases like this, the plants are often somewhat larger than what one would grow in a full sun rock garden.
Many of the shady plants are spring ephemerals, which disappear completely in May and June, so it is wise to intersperse them with plants that come up later and expand to take the place of those that have died down. They often have seeds that are also ephemeral, and so need to be planted as soon as possible after the seeds are ripe, but in many cases you can get these plants as bulbs, corms, or tubers rather than growing them from seed.