Zone 5 encompasses most of the Midwest, some northern states and parts of Utah, Nevada, Oregon and Washington state, according to the USDA Plant Hardiness Zone Map. Plants that are hardy to lows of -20 degrees Fahrenheit can survive in these areas. Among reliable shade plants for this zone are ferns, hostas and rhododendrum.
Many ferns, which are divided into several botanic families, are hardy in Zone 5. In general, ferns are perennials known for interesting foliage that can be small as a few inches or as tall as 50 feet, according to the 1997 Sunset National Garden Book. Ferns usually grow in forest-like settings and thrive with regular watering, partial to full shade and in well-drained soil. Ferns may be planted in containers, mixed in gardens to provide interesting shapes and varied heights, or as ground cover. Too look their best, ferns should be pruned regularly to remove dead fronds. Cinnamon, Japanese Tassel and Autumns are varieties that will thrive in shady areas in Zone 5.
Hostas (Funkia) are also known as plantain lillies, though the foliage is more interesting than the spiky, trumpet-shaped flower that appears in mid-summer. Hostas have leaf shapes--heart, oval, lance, or round--that radiate from a central clump. Leaves are colorful (green, chartreuse, gray or blue) and grow in unique textures including smooth, puckered or wavy. One of only a few plants that can thrive in full shade, hostas should be planted in partial to full shade and require regular watering. Sum & Substance and Ground Master varieties are appropriate choices for shady areas in Zone 5.
Rhododendrum (Rhododendrum) is an enormous family of plants that also includes azaleas. Evergreen and mostly available as shrubs, rhododendrum can add color to a shady spot in Zone 5. Available in purples, pinks, reds and white, the plants flower in the spring. In Zone 5, rhododendrum should be planted in filtered shade and have soil that is acidic and moist constantly. Some of the best varieties for cold weather are America, English Roseum and President Lincoln.