Many varieties of evergreens grow well in the harsh climate of the northern Great Plains of the United States, and the state of Iowa is no exception. To break up the frozen winter landscape in Iowa's USDA zone 4b and zone 5 climates, plant several different varieties of evergreens. Along with conifers like pine and spruce, plant broadleaf evergreens such as holly and rhododendron. The holly will produce bright red berries in autumn that stay on the plants well into winter. Rhododendrons will produce masses of delicate-looking flowers in early spring.
A series of hybrid hollies, (Ilex x meserveae), also called Meserve hollies, are reliably hardy through USDA hardiness zone 5, which covers the southern half of the state. Some varietal names are 'Blue Prince' and 'Blue Princess.' They have dark bluish-green foliage and attractive red fruit on bush-like plants that grow 5 to 10 feet high. Plant them in moist, well-drained soil that is slightly acid. Meserve hybrid hollies are adaptable to sites that get full sun or partial to mostly shade. Due to their propensity for winter injury, plant them on the east side of buildings or other protected sites to protect them from bright sun, which can burn the foliage, and drying winter winds.
A low-growing ground cover, wintercreeper (Euonymus fortunei) is one of the hardiest of the broad leaf evergreens. It grows reliably well through USDA hardiness zone 5 in southern Iowa and with winter protection in zone 4b, in northern Iowa. It grows well in either full sun or deep shade and prefers partial shade in hotter southern areas. Grows well in all soil types that have adequate drainage, but needs regular watering because it does not tolerate drought. Euonymus fortunei can be trained as a low-growing shrub or trained to climb the side of a building, as well as its use as a groundcover. It is a very fast growing plant.
A series of hybrid rhododendrons, Marjatta hybrids (Rhododendron x marjatta) has flower buds hardy to -35 degrees Fahrenheit. These rhododendrons grow best in sites that are protected from afternoon sun, but receive sun in the morning. The Marjatta series cultivars range in size from a low growing 2-foot-high variety called "Elviira" with red flowers to the 6 foot high "Hellikki" that has a dense spreading habit and dark violet-red flowers. Marjatta hybrid rhododendrons are hardy through USDA zone 4 and will grow well throughout the state of Iowa.