Soaptree yucca

Sun

Full sun.

Water

Low once established. Water young plants deeply but infrequently, letting the soil dry between waterings; keep nearly dry in winter.

Soil

Sandy, gravelly or rocky soil with excellent drainage. Tolerates alkaline soil; unsuitable for waterlogged ground or heavy clay without substantial drainage improvement.

Height

10-20 ft (3-6 m), with flower stalks extending above the foliage

Spread

6-10 ft (1.8-3 m)

Flowers

Tall, branched clusters of creamy-white, bell-shaped flowers in late spring and early summer; flowering can be irregular.

Foliage

Evergreen. Dense crowns of narrow, flexible, pale-green leaves with white marginal threads and sharp tips. Dead leaves often remain as a skirt around the trunk.

Growth

Slow, especially while young; trunk formation takes years.

Care needed

Low

• Deer resistant
• Drought tolerant
• Heat tolerant
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Very tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1.8 ft (0.54 m)

2. After 1 year

   3 ft (0.95 m)

3. After 2 years

   4 ft (1.4 m)

4. After 3 years

   6 ft (1.8 m)

5. After 5 years

   9 ft (2.6 m)

About 10 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Native to

the US

Growth rate

Slow

• Plant in spring on raised, freely draining ground where winters are wet.
• Water deeply during prolonged dry spells in the first growing season, then allow the soil to dry before watering again.
• Use gravel mulch around the base and keep soil, compost and organic mulch away from the trunk.
• Do not routinely fertilise established plants; rich feeding is unnecessary.
• Choose the permanent position carefully: its deep roots make established plants difficult to move.
• Keep sharp leaf tips away from paths, play areas and seating.

Pruning. Remove spent flower stalks near their base after flowering. In spring, cut off unwanted dead leaves close to the trunk without cutting into it or damaging the living crown; retaining the dry leaf skirt is also acceptable.

Spring

Plant young specimens after severe frost has passed, choosing a sunny site with sharp drainage.

Spring

Remove damaged leaves if needed and check that the growing crown remains firm.

Late spring

Watch for emerging flower stalks and keep nearby paths clear of foliage.

Summer

Water newly planted specimens during long dry spells, allowing the root zone to dry between soakings.

Late summer

Cut away finished flower stalks unless you want to retain developing seed capsules.

Autumn

Clear fallen leaves from the crown and check that surface water drains away from the base.

Winter

Avoid routine watering; in wet climates, protect container plants from persistent rain in a bright, airy position.

• Use as a single architectural specimen in a sunny gravel garden.
• Combine with low, drought-tolerant grasses and perennials so its trunk and leaf crowns remain visible.
• Plant against a plain wall to show the outline of its branching stems.
• Use in a spacious desert planting with agaves and other hardy yuccas, well back from paths.

Garden styles it suits: Desert modern, Architectural minimal, Desert / xeriscape, Dry gravel garden, Southwestern and Winter interest.

Plant it with: Red yucca, Parry's agave, Blue grama, Blackfoot daisy, Desert marigold and Pineleaf penstemon.

Wildlife: In its native range, specialised yucca moths pollinate the flowers and lay eggs in the developing ovaries; their larvae eat some of the seeds. Seed production is often absent where these moths do not occur.

• Root or crown rot in wet soil: improve drainage before planting, keep the crown clear and avoid winter irrigation; badly rotted plants rarely recover.
• Yucca weevils in regions where they occur: investigate wilting crowns and holes at the leaf bases; remove and dispose of badly infested plants.
• Scale insects: inspect leaves and stems, remove small infestations by hand and use a labelled horticultural oil if needed, avoiding hot sun during treatment.
• Cold damage, especially in damp winters: plant in a sheltered, freely draining site and wait until spring growth starts before removing damaged foliage.

Yucca tissues contain saponins and should be treated as toxic if eaten by cats, dogs or horses; ingestion can cause gastrointestinal upset, and substantial amounts may cause more serious illness. Raw plant material may also upset people's stomachs. Sharp leaf tips can injure skin and eyes.

• Beaked yucca (Yucca rostrata)

  Usually has a denser, rounded crown of stiffer blue-grey leaves, rather than the greener, more flexible, prominently thread-edged leaves of soaptree yucca.

• Joshua tree (Yucca brevifolia)

  Has much shorter, stiff, dagger-like leaves and a heavier, often irregularly branching framework.

• Banana yucca (Yucca baccata)

  Usually forms low clumps of broad, thick leaves and produces fleshy, banana-shaped fruit; soaptree yucca has narrow leaves, develops tall trunks and bears dry capsules.

The common name refers to the soap-like lather made from its saponin-rich roots and trunk, while the Latin elata means tall or lofty.

Propagation. Raise from seed in warmth in a sharply drained mix. Offsets can sometimes be separated with attached roots, but disturbance of established plants and their deep roots is risky.

Accepted botanical name

Yucca elata

In the US and Canada

Native in the lower 48 states.

Native range

Arizona, Mexico Northeast, Mexico Northwest, New Mexico and Texas.

Measured

Soil pH 7 to 8.5. Average height 500 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.