Yucca plant: growing Adam's needle and other outdoor yuccas, and how to remove one

At a glance

What a yucca plant is (and what it isn't)

Yuccas are evergreen, sword-leaved perennials and shrubs native to the Americas, from the southeastern coastal plain through the Great Plains and the desert Southwest into Mexico. They belong to the asparagus family (Asparagaceae), in the same subfamily as agaves. In a garden, the yucca most people mean is Adam's needle (Yucca filamentosa). It forms a stemless rosette of stiff, blue-green to green leaves edged with curly white threads. In early summer it sends up a tall stalk of creamy white, bell-shaped flowers.

Four mix-ups cause most of the confusion around the word "yucca":

• Yucca is not cassava. The starchy root sold as "yuca" for fries and stews is cassava (Manihot esculenta), an unrelated tropical shrub. The ornamental yucca in your yard is not a root vegetable.
• Red yucca is not a yucca. Hesperaloe parviflora has narrow, grass-like leaves and coral-red flowers. It is a related desert plant in a different genus.
• Agave is not a yucca. Agaves share the same subfamily and a similar spiky rosette, but their leaves are thick and fleshy rather than tough and fibrous. Compare them in the agave plant guide.
• Indoor "yucca cane" is a tender species. The spineless yucca (Yucca gigantea, often sold as Y. elephantipes) is grown as a houseplant in most of the country. It survives outdoors only in frost-free climates. This guide covers the hardy outdoor yuccas.

Outdoor yucca species compared

Dozens of Yucca species exist. A handful are widely planted, and they differ a lot in cold tolerance, size, and how well they handle humid, rainy summers. Zones below are from NC State Extension's Gardener Plant Toolbox.

NC State lists both Adam's needle and soapweed yucca as resistant to deer, and describes soapweed as among the most cold-hardy of the yucca species.

Which yucca for your region

Top-ranking yucca guides usually list species without saying where each one actually thrives. Rainfall and winter wetness matter as much as winter lows, so match the species to your climate as a whole:

In the desert, the bigger risk is too much irrigation, not too little; see the desert garden watering schedule. For the Northeast, Adam's needle is the safe default: NC State lists it for zones 4–10 and rates it tolerant of salt spray, drought, and poor soil.

Where to plant yucca outdoors

Yucca needs two things: sun and drainage. Get those right and it asks for almost nothing else.

• Light: full sun is ideal. Adam's needle also grows in part shade; UF/IFAS notes it tolerates partial shade well if enough air circulates to keep the plant on the dry side.
• Soil: sandy, gravelly, or rocky soil that drains fast. UF/IFAS rates Adam's needle high in drought tolerance and good in soil-salt tolerance, and lists sand among the soils it tolerates, which is why it suits coastal and sandy-soil gardens. Wet soil is the problem: NC State notes soapweed cannot survive waterlogged conditions, and Adam's needle is prone to leaf spots and blight where drainage is poor.
• Placement: leaf tips are sharp. UF/IFAS recommends setting Adam's needle 3–4 feet back from the edge of a walk or patio; give play areas the same clearance.
• Uses: dry slopes, rock gardens, gravel beds, parking strips, seaside plantings, and xeriscapes.

For companions that share these conditions, see perennials for sandy soil and perennials for rocky and thin soil. If you are unsure how your soil drains, a simple perc test answers the question in an afternoon.

How to plant a yucca

1. Plant in spring or early fall, so roots establish before summer heat or a hard freeze.
2. Dig a hole as deep as the root ball and two to three times as wide. Skip rich amendments. Yucca grows best in lean soil, and pockets of compost can hold too much water.
3. In heavy clay, build up instead of digging down. Plant on a low mound or berm of native soil mixed with coarse gravel so the crown sits above any standing water. UC IPM recommends mounds or raised beds for agaves and yuccas for this reason.
4. Set the crown at or slightly above grade. A buried crown invites rot.
5. Water to settle the soil, then water about once a week for the first month or two if there is no rain. Once established, yuccas rarely need watering outside of severe drought.
6. Mulch with gravel, not wood. A gravel or stone mulch keeps the crown dry. Shredded bark against the crown holds moisture.

Yucca care through the year

Trimming and pruning a yucca

Stemless yuccas like Adam's needle need no shaping. Cut off only dead leaves and old flower stalks. Do not shear the green leaves; they do not regrow from a cut end, and the plant just looks butchered. Trunk-forming yuccas such as Spanish dagger can be cut back to reduce height. New rosettes usually sprout below the cut, and the removed top can be rooted as a new plant. Use sharp tools: bypass loppers handle most flower stalks, and a pruning saw handles woody trunks.

Flowering

Established Adam's needle blooms in late spring to early summer; NC State lists April to June in North Carolina, with waxy white flowers on stalks 5–8 feet tall. Pollination depends on a remarkable partnership. The USDA Forest Service explains that each yucca species is paired with its own yucca moth: the female gathers pollen, lays a few eggs in the flower's ovary, and then deliberately places pollen on the stigma so the flower sets fruit. NC State adds that the larvae eat some, but not all, of the developing seeds. Flowers the moths do not visit generally do not set seed pods.

Propagating yucca

Yuccas spread by offsets (pups) around the base and by underground stems. Both make propagation easy.

1. Find a pup with several leaves that is growing at the edge of the clump.
2. Dig down beside it and cut the connection to the parent with a sharp spade, keeping any roots attached.
3. Let large cut surfaces dry for a day or two in the shade so they callus.
4. Plant in lean, gritty soil and water lightly until it is anchored.

Sections of root left in the soil often sprout on their own. That helps propagation, and it is the main reason yuccas are hard to get rid of.

How to remove yucca for good

"How to kill a yucca plant" is one of the most searched yucca questions, and the reason is biological. Yuccas store water and energy in a deep taproot and rhizomes, and Nebraska Extension notes they can regenerate even after losing the entire top of the plant. Plan on removing as much of the root system as possible and then watching the site for a full growing season.

1. Gear up. Wear heavy gloves, long sleeves, and eye protection. The leaf tips can puncture skin and injure eyes.
2. Cut the foliage off at ground level to expose the crown. On trunk-forming yuccas, cut the trunk down in sections.
3. Dig out the crown and the main root mass. Trench around the plant with a sharp spade and pry the root mass up. Follow thick roots outward and remove as much of them as you can. A mattock or root saw helps on mature clumps.
4. Sift the backfill and remove fleshy root pieces.
5. Watch for resprouts for the rest of the season. Dig out each new rosette as soon as it appears, roots and all. Repeated removal eventually exhausts what the roots have stored.
6. Herbicides, if you use them, must be products whose label lists yucca or the site. Nebraska Extension's guide Managing Soapweed Yucca notes that mowing gives only short-term control because yucca regrows from its rhizomes and taproot (which can reach 20 feet deep), and it describes a directed herbicide spray into the center of the leaf whorl for rangeland yucca. Read and follow the product label; it is the legal guide for rates and sites.

Household bleach, salt, and similar home remedies are not labeled herbicides. They can damage the soil for other plants and are not a reliable fix. If you are replacing a yucca bed with other low-water plants, see xeriscape alternatives to lawn for options suited to sunny, dry sites.

Problems, pests, and safety

UC Statewide IPM describes the agave weevil (Scyphophorus acupunctatus) and yucca weevil (S. yuccae): larvae tunnel into the base of the plant, and damaged plants commonly collapse as decay organisms move in. UC IPM notes that direct control is difficult and that good drainage, full sun, and little irrigation are the main prevention. Elsewhere, UF/IFAS reports no serious pests on Adam's needle when its growing needs are met.

Pets: the ASPCA lists yucca as toxic to dogs, cats, and horses. It names saponins as the toxic principle, with vomiting as the sign in dogs and cats, and liver disease and skin inflammation (dermatitis) in horses. If a pet chews on a yucca, contact your veterinarian or the ASPCA Animal Poison Control Center.

Common mistakes

Frequently asked

What does a yucca plant look like?

Most garden yuccas form a rosette of stiff, sword-shaped leaves that radiate from a central crown; Adam's needle leaves run up to about 18 inches long, and soapweed leaves 1 to 2½ feet. Adam's needle has curly white threads along the leaf edges. In late spring or early summer, a stalk of white, bell-shaped flowers rises well above the foliage.

How do you get rid of yucca plants?

Cut off the foliage, then dig out the crown and as much of the thick root system as possible, because root pieces resprout. Dig up any new sprouts as soon as they appear through the following season. If you use an herbicide, use one whose label lists yucca or the site, and follow the label exactly.

How often do yucca plants bloom?

Established plants bloom once a year in late spring to early summer; NC State lists April to June for Adam's needle in North Carolina, on stalks 5–8 feet tall. Flowers are pollinated only by yucca moths, so seed pods form only on flowers the moths visit.

Are yucca plants toxic to dogs and cats?

Yes. The ASPCA lists yucca as toxic to dogs, cats, and horses because of saponins; it lists vomiting as the sign in dogs and cats. Call your veterinarian or the ASPCA Animal Poison Control Center if a pet eats part of the plant.

How do you trim a yucca plant?

Cut dead lower leaves and spent flower stalks off at the base, wearing thick gloves and eye protection. Leave healthy green leaves alone, since cut leaves do not regrow. Trunk-forming yuccas can be cut back to reduce height, and new rosettes usually sprout below the cut.

Do yucca plants need full sun?

Full sun is ideal, but Adam's needle also grows in part shade; UF/IFAS notes it tolerates partial shade well if air circulation keeps the plant dry. Excellent drainage matters even more than sun: yuccas tolerate drought far better than wet soil.

Is yucca the same as cassava?

No. The edible root sold as "yuca" is cassava (Manihot esculenta), an unrelated plant. Ornamental yuccas are grown for their foliage and flowers, not for an edible root, and they are toxic to pets.

How big do yucca plants get?

Adam's needle forms a clump of foliage up to about 3 feet tall and 3–5 feet wide, with flower stalks reaching 5–8 feet, per UF/IFAS and NC State. Trunk-forming species get much larger: NC State lists Spanish dagger up to 16 feet and beaked yucca at 5–15 feet.

Sources

1. Yucca filamentosa (Adam's Needle Yucca), NC State Extension Gardener Plant Toolbox
2. Yucca glauca (Soapweed Yucca), NC State Extension Gardener Plant Toolbox
3. Yucca gloriosa (Mound Lily Yucca, Spanish Dagger), NC State Extension Gardener Plant Toolbox
4. Yucca rostrata (Beaked Yucca), NC State Extension Gardener Plant Toolbox
5. Yucca flaccida (Weakleaf Yucca), NC State Extension Gardener Plant Toolbox
6. Yucca gigantea (Spineless Yucca), NC State Extension Gardener Plant Toolbox
7. Yucca filamentosa: Adam's Needle (FPS-615), University of Florida IFAS Extension
8. Yucca Moths (Pollinator of the Month), USDA Forest Service
9. Agave and Yucca Weevils, UC Statewide IPM Program
10. Managing Soapweed Yucca (G2086), Nebraska Extension
11. Yucca, ASPCA Animal Poison Control

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