Soapweed yucca

Sun

Full sun; flowering and leaf form are best in an open position.

Water

Low once established; water young plants during prolonged dry spells and avoid persistently wet soil.

Soil

Sharply drained sandy, gravelly or rocky soil; tolerates poor soil and alkaline conditions. Unsuitable for waterlogged ground.

Height

2-3 ft (0.6-0.9 m) in leaf; 4-6 ft (1.2-1.8 m) in flower

Spread

2-3 ft (0.6-0.9 m) per rosette; older colonies can spread farther through offsets

Flowers

Late spring to midsummer; upright clusters of nodding, creamy-white to greenish-white, bell-shaped flowers.

Foliage

Evergreen. Stiff, narrow, blue-green to grey-green leaves with fine white threads along the margins and a sharp terminal point.

Growth

Slow to moderate

Care needed

Low

• Pollinators
• Deer resistant
• Drought tolerant
• Cold hardy
• Heat tolerant
• Wildlife
• Low allergen

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

Difficulty

Easy

Toughness

Very tough

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

1. Planting day

   0.8 ft (0.25 m)

2. After 1 year

   1 ft (0.31 m)

3. After 2 years

   1.2 ft (0.38 m)

4. After 3 years

   1.5 ft (0.44 m)

5. After 5 years

   1.9 ft (0.57 m)

About 8 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 and Canada

Growth rate

Slow

• Plant with the crown at soil level in freely draining ground; use a raised gravel bed where winters are wet.
• Water deeply after planting, then let the soil dry between waterings while roots establish.
• Established plants usually need no irrigation except during unusually prolonged drought.
• Do not routinely fertilise; rich feeding is unnecessary.
• Use a thin gravel mulch rather than moisture-holding organic mulch against the crown.
• Wear gloves and eye protection when working among the pointed leaves.

Pruning. Cut spent flower stalks close to their base after flowering, unless you want to keep seed capsules. In spring, remove fully dead leaves with secateurs without cutting into the crown or trimming healthy leaf tips.

Spring

Remove dead leaves and check the crown for winter rot.

Spring

Plant new specimens or separate well-rooted offsets once the soil is workable and draining freely.

Late spring

Water recent plantings during dry weather, allowing the soil to dry between soakings.

Summer

Remove finished flower stalks, or leave capsules to mature where seed has set.

Autumn

Clear fallen leaves from the rosettes and keep drainage channels open.

Winter

Avoid watering dormant outdoor plants and protect container plants from prolonged saturation.

• Use as a sculptural accent in a sunny gravel garden, with low-growing stonecrops around the base.
• Combine with prairie grasses and drought-tolerant flowering perennials for contrasting leaf shapes.
• Repeat small groups through a dry border to provide evergreen structure.
• Plant on a sunny, freely drained bank where irrigation is difficult, leaving room for offsets.

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

Plant it with: Blue grama, Little bluestem, Prairie dropseed, Purple prairie clover, Blanket flower and Stonecrop.

Wildlife: In its native range, specialist yucca moths pollinate the flowers and their larvae eat some developing seeds. Seed production may be absent where these moths do not occur; the foliage also provides shelter for small animals.

• Crown or root rot in wet soil: improve drainage or move a healthy offset to a raised, gritty bed; discard soft, rotting material.
• Leaf spots in damp conditions: remove badly affected dead foliage, improve airflow and avoid overhead watering.
• Scale insects: inspect leaf bases and remove small infestations by hand; use a labelled horticultural oil if needed.
• Failure to flower: provide full sun and avoid heavy feeding; young plants and recently divided offsets may take several years to bloom.

Yucca contains steroidal saponins and is considered toxic to cats, dogs and horses if eaten, with vomiting or diarrhoea possible; substantial ingestion warrants veterinary advice. Raw plant material can also upset the human digestive system and should not be treated as food. Sharp leaf tips can puncture skin or injure eyes.

• Adam's needle (Yucca filamentosa)

  Usually has much broader, flatter leaves with conspicuous curling marginal threads; soapweed has distinctly narrow, grasslike leaves.

• Banana yucca (Yucca baccata)

  Has broader, thicker leaves and fleshy, banana-shaped fruit; soapweed produces dry seed capsules.

• Red yucca (Hesperaloe parviflora)

  Has arching, channelled leaves and slender stalks of tubular coral-red or yellow flowers rather than broad, creamy yucca bells.

The epithet glauca means blue-grey or glaucous, referring to the foliage, while soapweed refers to the saponin-rich roots traditionally used for washing.

Propagation. Separate rooted offsets in spring, keeping as much root as possible, and replant in sharply drained soil. Alternatively, sow ripe seed in a freely draining mix; seedlings grow slowly and may take several years to flower.

Accepted botanical name

Yucca glauca

In the US and Canada

Native in Canada and the lower 48 states.

Native range

Alberta, Colorado, Iowa, Kansas, Missouri, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota and Texas.

Measured

Soil pH 7 to 8.5. Average height 30 cm.

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