Adam's needle is a great plant for Southwest-themed landscaping. Known in plant taxonomy as Yucca filamentosa, the plant is a broadleaf evergreen shrub. Adam's needle is related to many other commonly grown cacti and succulents, and the family to which it belongs reveals another surprising relative: asparagus.
Appearance and Foliage
Adam's needle grows to a height of about 2 to 3 feet (not counting the flower stalk) at maturity, with a spread slightly smaller than the height. The leaves are blade-like and form a basal rosette (beginners may think that the leaf shape resembles that of bearded iris, although long-time gardeners may disagree.) The slender leaves, which end in a spine, can reach a length of over two feet long on large plants. Curled threads line the edges of the leaves, giving it its species name—filamentosa, meaning a thread or "filament."
The flower stalk that grows up from the center of the foliage in late spring can double the height of this yucca plant over time, sometimes growing to over eight feet tall. The flower cluster usually appears right around the beginning of summer (in a zone-5 landscape). The individual blooms take the shape of nodding, white bells. It can take a long time for a new Yucca filamentosa to bloom for the first time, often about three years.
Growing Zones and Sun/Soil Needs
Adam's needle needs well-drained soil, and it should be kept a bit on the dry side. It does not need fertile soil, so it is a good choice for an area that has poor soil. It also does not seem to mind pollutants, making it suitable for roadside plantings. This plant grows best in full sun but will tolerate a little shade.
Caring for Adam's Needle
This succulent is one of the easiest plants to grow outdoors. Very little care is needed for it so if landscape maintenance is not your cup of tea, Yucca filamentosa could be an ideal plant for you. At most—and only if you're fussy about the look of your landscape—you might want to cut off the spent flower stalks at the end of the year and occasionally remove old leaves that have turned brown.
Similar Yucca Plants
There are many other types of yucca plants besides Yucca filamentosa, including:
- Yucca elata, or soap-tree yucca, a tree form that can reach 15 feet tall. It can be grown in zones 5 to 8.
- Yucca glauca, sometimes called "soapweed," not to be confused with soap-tree yucca. This plant is suitable for zones 3 to 10.
- Yucca flaccida derives its species name from the fact that its leaves stand fairly limp (those on most yucca plants are rigid); it grows in zones 4 to 10.
- Yucca brevifolia, the well-known Joshua tree of the American Southwest and another type of tree-form yucca suitable for zones 6 to 8.
- "Bright Edge" Yucca filamentosa is a bicolored type of Adam's needle—even brighter are the variations with gold in their leaves, such as "Golden Sword" and "Garland’s Gold." Bright Edge Adam's needle grows best in zones 4 to 9.
The calling card for Adam's needle may well be, first and foremost, that it is a tough plant. It is a drought-tolerant ground cover that is also salt-tolerant. Pests and insects give it very little trouble, and it is both deer-proof and rabbit-proof. Adam's needle attracts butterflies but also draws earwigs; these pests are unlikely to do any serious damage to the plants, however.
Uses in Landscaping
The potential uses for this yucca plant in your yard are many, based both on how it looks and how hardy it is. Even though Yucca filamentosa is a native of the Southeastern United States, it is a great fit in a Southwestern theme as well, since it looks like it belongs in a desert. You can also make use of the fine texture of its leaves by growing it next to plants that have foliage of a coarser texture, thereby creating some contrast.
Its well-known toughness makes Adam's needle a good fit in dry regions or problem areas of landscapes that seem too dry for most plants. Consider it as an option for xeriscaping, a form of sustainable landscaping. Yucca is also a great choice when growing a rock garden, and it works well on a slope, to provide valuable soil erosion control.