How Hardy Is Dwarf Yaupon Holly?

What is Hardy?

• In horticulture, the word hardy has multiple meanings, depending on the context of conversation. Almost by default, when a gardener mentions plant hardiness, it refers to the plant's ability to survive winter-cold temperatures in any region. However, a plant being described as hardy can also imply its ability to grow without much care or maintenance. In this context, a hardy plant means it is tough, durable and hard to kill, even for the most novice of gardeners.

Winter Hardiness

• Dwarf yaupon holly shrubs are best grown only in U.S. Department of Agriculture plant hardiness zones 7 through 11a. While tolerant of summer heat, this holly species is not as able to survive cold compared to other hollies. Temperatures colder than minus 5 degrees F kill the plant, and 0 degrees results in irregular branch dieback. Sustained subfreezing temperatures over several weeks, with nighttime lows in the single digits can also kill dwarf yaupon holly shrubs, mainly when the plants are weak and stressed from drought or disease.

Sunset Climate Zones

• Gardeners, particularly in and west of the Rocky Mountains, have difficulty using the USDA hardiness zone designations, as they quickly and vaguely change with elevation in the mountains and valleys. Instead, "Sunset" magazine researched and developed an extensive climate zone system that uses winter cold, summer heat, rainfall, soil, latitude and elevation to describe plant hardiness. Dwarf yaupon hollies are hardy in Sunset climate zones 3 through 9, 11 through 24 and in H1, H2. In the eastern states, the plant is also hardy in climate zones 25 through 32, and the warmest winter areas of zones 33 and 36.

Summer-Heat Tolerances

• Even though dwarf yaupon holly shrubs tolerate lots of heat, they are not well suited to the alkaline soils and aridity of the Desert Southwest. The best growth and vigor occurs in regions with warm summers, such as experiencing more than 60 days of temperatures reaching at least 86 degrees F. This equates to American Horticultural heat zones 12 through 7. However, dwarf yaupon holly does well in cool summer areas if grown in full sun and winters aren't too cold.

Alternative

• If you garden in slightly colder winter areas than where the dwarf yaupon holly is reliably hardy, grow a different but similar holly. Japanese holly (Ilex crenata) also develops mounding shrubs with tiny green leaves and few berries -- and can be used in the same landscape applications as the dwarf yaupon holly.