Adam's Needle Yucca
Hardiness zone range
Wonderful, stately evergreens with huge, fragrant, ivory-white, flower panicles and marvelous, sword-like leaves that spread outwards from a basal rosette to give the whole plant a special sculptural or architectural quality.
Culture & Care
They thrive best in reasonably fertile soils that are well-drained and have the capacity to retain moisture in dry weather, so improving the site at planting time by incorporating extra organic matter (peat, planting compost, etc.) into the surrounding soil will encourage good vigorous growth and plenty of luxuriant foliage. They are reliable and very easy to grow on most sites, providing they have good drainage. Under no circumstances will they tolerate poor drainage or waterlogged conditions; on the other hand, once established, they are tolerant of poor soils, variation in pH levels, compacted soils, heat, drought, and even winter salt spray. They are seldom attacked by any serious pests or diseases, and the only maintenance that is required is to occasionally remove old leaves and the flowering stalk after flowering to prevent the formation of unwanted seeds. Choose the site carefully because once they become established the deep, tuberous taproots can be difficult to remove, with portions often persisting to sprout and re-emerge.
The exotic, desert-like appearance makes them ideal for beds around patios, decks, and swimming pools, and other sun drenched positions like sloping banks and hillsides. They are great in containers, raised beds, rock gardens, gravel gardens, and xerophytic gardens where the soil is light, rocky, or sandy, and heat and drought tolerance is a priority. They form bold, dramatic clumps of spiky foliage and tall, sweetly, night-scented, flower stems, so they are ideal as evergreen accent plants to create focal points in borders, island beds, or framing entranceways, steps, and pathways. They can be used as single specimens in perennial beds or grouped in larger numbers where the massed effect is stunning. The evergreen foliage lasts well in cut flower arrangements, and the enormous flower heads are incredible for placing in large arrangements to make dramatic impact in large rooms and entrance areas.
The botanical name is easy to remember because it sounds rather unflattering. It actually comes from Iucca, a Caribbean name for the root of Manihot esculenta (which is used for making cassava and tapioca); the swollen "toes" resemble those of this tender, tropical food plant, and, when the first plants were introduced around 1550, the herbalists were confused and misidentified it. By the time Linnaeus and other botanists correctly identified it as a completely different plant, the name was firmly established, so the genus became known as Yucca. They are native to southern parts of North America, Central America, and the West Indies. Only a few of the 40 or so species are suitable for our gardening zones, and, of these, the most commonly encountered is Yucca filamentosa and its variants. It makes dense, slowly spreading, evergreen clumps of grayish-green, sword-like leaves with curly, thread-like filaments that give rise to the species name, filamentos. In early to mid summer, they produce sturdy, 6-8 feet tall spikes that are loaded with numerous, ivory white, waxy, bell-shaped flowers, all hanging downwards from side growths to look like chandeliers on stems. These huge flower panicles are very impressive, providing structure and height to beds and borders, and, when they are seen standing proudly above the marvelous architectural foliage, the combined effect is stunning. Our favorite is the variegated form, Yucca 'Golden Sword'. It is a superb garden plant with green-margined, sword-like leaves that have a broad, golden-yellow center in each leaf blade. Because they are less rigid than some of the other species, they often reflex at the tips to hang downwards to make an eye-catching foliage display, especially in autumn, winter, and spring. The clumps get to about 3 - 4 feet high with summer flower stalks that are an amazing 3 to 8 feet tall with beautiful, ivory-white, bell-shaped flowers. It has received an Award of Garden Merit from the Royal Horticultural Society in Great Britain.
The variegated forms are not quite as hardy as the usual green forms; therefore, if you garden in the colder parts of Zone 4, think about putting down an extra layer of insulating mulch in late autumn or early winter. A good deep layer of 2-4 inches will help to protect the crown and roots during the worst part of the winter. In spring, when the temperatures start to rise, it should be raked back and spread over a greater area to help retain soil moisture and reduce weed competition. Alternative materials like straw bales, proprietary insulating materials, even old carpets can be used, but since these can be unsightly and a host for vermin, we find that mulch (especially hardwood mulch) is the most effective and attractive option.
They look great springing up out of low spreading ground cover, and are often used in perennial plantings with Sedums, Delospermas, Dianthus, Coreopsis, Liriope, and silvery carpets of Stachys (Lambs Ears), or with low growing, woody partners like Genista, Cotoneasters, Arctostaphylos, Ilex 'Helleri', Junipers, and Microbiota decussata, where the spiky leaves and tall spires sharpen up the soft foliage giving the plantings a strong, vertical emphasis. They are sun lovers and are tremendously useful in situations where the site is hot and dry, reveling in the hot summer sun with drought tolerant Vitex (Chastetree), Lespedeza 'Gibraltar', Cytisus (Scotch Broom), and taller growing perennials like Achilleas, Agastache, Gauras, Echinaceas, and Rudbeckias (Black Eyed Susan). If the soil is reasonably fertile and able to retain some moisture, Gypsophila (Baby's Breath) Heucheras, Perovskia, and Salvias (ornamental sage) will give nice contrasts and plenty of supporting color. Flowering shrubs like Caryopteris, Lagerstroemias, Buddleias, Hibiscus, and Hydrangeas will enjoy the same conditions and provide lots of summer color. Where the space only permits a few plants, think about trying them with Lavenders, Scabiosa 'Pink Mist and 'Butterfly Blue', Asters, and Stokesias.