Growing Yuccas in Zone 4
Southwestern plants are appealing due to their diversity and adaptability. Yuccas are primarily found in the tropical to subtropical Americas and tend to prefer warm, dry regions. However, there are some cold-hardy yucca varieties that are suitable for extremely cold temperatures. In fact, even though we associate these relatives of Agave with desert heat and dryness, some forms have been found growing in the crisp region of the Rocky Mountains in winter. You just need to make sure you choose an appropriate variety with cold tolerance and adaptability to freezing temperatures. Simply selecting cold-hardy specimens is no guarantee they will thrive in such extreme weather conditions. Heavy snow can damage foliage and deep freezes that are longer than a week can adversely affect the roots of shallowly planted yucca. Some tips can help successfully grow yuccas in zone 4.
Planting your yucca in a microclimate in your garden can help protect the plant from some of the cold temperatures. Using a southern-facing wall or fence can help reflect the winter sun and produce a moderately warmer region. It also reduces the plant’s exposure to cold northerly winds. Do not water plants before a hard freeze, as excess moisture in the soil can turn into ice and damage the roots and crown.
In extreme cases, growing yuccas in zone 4 may require more obvious protective steps. Use organic mulch around the root zone in a layer of up to 3 inches (7.5 cm.) and protect plants in exposed situations by placing plastic over the entire plant during the night. Remove it during the day so moisture can escape and the plant can respirate.
Zone 4 Yucca Plants
Some yuccas can grow into trees, such as the Joshua tree, while others retain a tidy, low rosette perfect for containers, borders, and accent plants. The smaller forms are usually hardy in areas with consistent snow and freezing temperatures.
Yucca glauca, or small soapweed, is one of the best winter hardy yuccas and has lovely narrow bluish-green leaves. The plant is hardy in much of the Midwestern United States and can withstand temperatures of -30 to -35 Fahrenheit (-34 to -37 C.). The tidy little 2-foot (61 cm.) tall Yucca harrimaniae, or Spanish bayonet, has very sharp leaves as the name suggests. It is drought tolerant and thrives in cold winter regions. The dwarf yucca, Yucca nana, seems made for container growing. It is a neat little plant of only 8 to 10 inches (20.5 to 25.5 cm.) in height. Adam’s needle is a classic cold-hardy yucca. There are several cultivars of this zone 4 plant, Yucca filimentosa. ‘Bright Edge’ has gold margins, while ‘Color Guard’ has a central cream stripe. Each plant approaches 3 to 5 feet (1 to 1.5 m.) in height. ‘Golden Sword’ may or may not be in the same species depending upon who you consult. It is a 5- to 6-foot (1.5 to 2 m.) tall plant with narrow leaves sliced through the center with a yellow stripe. These yuccas all produce flower stalks decorated with creamy bell-shaped flowers. Yucca baccata is another cold hardy example. Also known as banana or Datil yucca, it can survive temperatures of -20 degrees Fahrenheit (-28 C.) and possibly colder with some protection. Plants have blue to green leaves and may produce thick trunks.
