Adam's needle (Yucca filamentosa) is a broadleaf evergreen shrub that is often used in Southwest themed landscapes, event though it is native to the Southeast U.S. 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.
Adam's needle is a virtually stemless shrub that looks more like a perennial plant. The blade-like leaves form a basal rosette ending in spines. The foliage clumps are usually 2 to 3 feet tall, with curled threads lining the edges of the leaves, giving it its species name—filamentosa—meaning a thread or "filament."
Mature plants send up flower stalks from the center of the foliage in late spring, which can double the height of this yucca plant, sometimes growing to over 8 feet tall. The flower cluster usually appears right around the beginning of summer, with individual blooms taking the shape of nodding, white bells.
This is a slow-growing plant, which may not produce flower spikes until it is four to five years old. Adam's needle can be planted almost any time, though it is most commonly available at nurseries in the spring. However, transplanting, or taking basal offsets of Y. filamentosa is best done in the fall.
|Botanical Name||Yucca filamentosa|
|Common Names||Adam's needle, needle palm, Spanish bayonet|
|Plant Type||Broadleaf evergreen shrub|
|Mature Size||4 to 8 feet tall, 2- to 3-foot spread|
|Sun Exposure||Full sun|
|Soil Type||Dry to medium-moisture, well-drained soil|
|Soil pH||5.5 to 7.5 (acidic to slightly alkaline)|
|Bloom Time||June to July|
|Flower Color||Creamy white|
|Hardiness Zones||5 to 10 (USDA)|
|Native Area||Sandy beaches and fields of Southeastern U.S.|
How to Grow 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. The only thing usually required—and only if you're fussy about the look of your landscape—is to cut off the spent flower stalks at the end of the year and occasionally remove old leaves that have turned brown.
Though this is a slow-growing plant, it's best to give it 2 to 3 feet of space around the plant, which will make it easy to work around the spiky leaves. Create a planting hole about twice as deep and wide as the nursery container, and plant the specimen at the same level as it was growing in the container.
Warmer regions will require almost no winterizing, but in colder regions, prepare the plant for winter by withholding all water. As the ground freezes, cover the plant with a 6- to 8-inch layer of mulch to protect the crown. Remove this mulch in the spring as the ground thaws.
Yucca filamentosa has virtually no serious disease or pest issues. Adam's needle attracts butterflies but also draws earwigs; these pests are unlikely to do any serious damage to the plants, however.
This plant grows best in full sun but will tolerate a little shade.
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 areas with poor, rocky or sandy soil. It also does not seem to mind pollutants or salty soil, making it suitable for roadside plantings.
Adam's needle has good tolerance for drought once established, and it is often used in xeriscape landscaping. In its first year, it should be watered lightly every week, but after this, it probably will not need supplemental watering at all. However, container-grown plants do need a small amount of weekly water.
Temperature and Humidity
Although native to the Southeastern U.S., this hardy succulent has naturalized farther north. You can plant Yucca filamentosa in USDA Hardiness Zones 5 to 10, where it readily adapts to all climate variations within those zones. This plant usually readily survives temperatures down to 5 degrees Fahrenheit, but if covered with mulch over winter, it will survive temps of minus 10 to minus 20 degrees.
Adam's needle usually does fine without any feeding, but if the plant is languishing, feed it once in spring with a granular general-purpose fertilizer mixed into the soil around the base of the plant.
Flower stalks can be trimmed down once the blooms have faded. Winter burn may affect some of the leaves in regions with cold, windy winters. While wearing sturdy gloves, prune away these leaves down close to the base of the plant. In cold regions, all leaves may die back in the winter.
Growing in Containers
Like other Yuccas, Adam's needle can make a good specimen for large containers. Use a porous succulent/cactus potting mix. Adam's needle generally prefers to be alone in its pot, but it blends well with other large potted plants arranged on a patio or deck, or around a sunny entrance.
Propagating Adam's Needle Plants
Mature plants will begin to grow basal offsets around the base of the plant, and these can be easily cut away and replanted to propagate new plants.
Varieties of Adam's Needle
A number of bi-colored, variegated cultivars are available. 'Bright Edge' is one good bicolored type of Adam's needle. It is well suited for zones 4 to 9. Even brighter are the variations with gold in their leaves, such as 'Golden Sword' and 'Garland’s Gold'.
Adam's Needle vs. Other Yucca Plants
There are many other types of yucca plants besides Yucca filamentosa, including:
- Yucca elata, or soap-tree yucca, is a tree form that can reach 15 feet tall. It can be grown in zones 5 to 8.
- Yucca glauca, sometimes called "soapweed," is 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, is another type of tree-form yucca suitable for zones 6 to 8.
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 U.S., 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.