soap weed plant

Plant Profiles

Soapweed Yucca

With such delicate blue-green leaves, it’s a wonder this yucca is hardy to Canada. And “soapweed?” If you crush its roots in water, they release enough sort-of-soap that you can wash your clothes. This is a plant of surprising talents.

Soapweed yuccas are usually as alert as porcupines caught in tight corners: hemispherical and fierce. Mine is floppy because my soil is too rich, and my drainage too slow.

This Spring I’ll replant it in a raised bed filled with soil that’s gritty and lean. Then this yucca will become the fearless all-weather sculpture it was born to be.

Here’s how to grow this hardiest of yuccas:

Agavaceae, the Agave family.

What kind of plant is it?

Hardy evergreen perennial.

Zone 3 with fantastic drainage; normally Zones 4 – 8

Clumping and hemispherical, with a short trunk that prefers to snake slowly along the ground. In leaner settings than mine, the needle-tipped foliage is bayonet-stiff. Offsets gradually to form colonies.

Size in ten years

A main stem of growth, with foliage to about three feet tall and four feet across, accompanied by smaller offsets quite close to the mother ship.

Sculptural and grassy.

its narrow blue foliage: When the plant is growing in lean and sunny surroundings, the leaves are rigid. Each is tipped with a single needle-sharp spine. To avoid leaving blood samples, approach this plant only when you are operating fully in the moment.

its imperviousness to deer: They don’t want to leave blood samples on the leaves, either—especially when they would be given lingually. Ouch.

its hardiness: Yucca glauca is native to Minnesota. Enough said.

its symbiosis with its insect pollinators: Yucca moths lay their eggs in the flowers but also pollinate them. Only a few of the resultant seeds become the food for the developing larva. The yucca cannot set seed without the moths, and the moths feed on no other plant than the yucca.

its roots: These can be ground up and mashed, to release one of the precursors to soap.

Mid-Summer. The spikes of ivory flowers are not nearly as tall or showy as those of larger species such as Y. filamentosa. They are pleasant but are secondary to the year-round presence of the foliage.

The ivory flowers go with anything; it’s the pale blue foliage that needs some color coordinating. To my eye, this means near neighbors that celebrate blue, burgundy, white, blue, or pale yellow.

Both the color and the form of Yucca glauca inspire dramatic partners. The narrow and rigid foliage is the natural contrast to foliage that is rounder, or feathery, or large. Its pale blue color craves the complements of white; pale pinks, blues, or yellows; and burgundy. When possible, combine with plants that partner both in form and in color. They’ll also need to be sun-lovers as well as connoisseurs of sharp drainage.

The round foliage of purple smoke bush glows when the sun passes through it; this shrub is never less than large, though, and would need to be planted only to the North or East of the Yucca so as not to block the all-important hot sun from the South and West. For plants with round purple foliage that can be planted even on the sunny side of the Yucca, consider purple-leaved sedums such as ‘Matrona’ or, much lower and almost a groundcover, ‘Vera Jamison’.

There are plenty of hardy cacti to explore; prickly pear is also native, amazingly, to Canada. While they require fantastic drainage whereas yucca merely prefers it, Yucca glauca will go toe-to-toe with any of them when you’re gardening outside the cacti’s prefered haunts of out-and-out deserts: The grittier the soil, the better.

A feathery partner every bit the equal of Yucca glauca in hardiness as well as craving for sun and good drainage is leadplant, Amorpha canescens. It also has the same native habitat. Junipers can provide feathery growth at any scale, and therefore at any side of the Yucca. In front, the resolutely prostrate habit of many Juniperus horizontalis cultivars is usually accompanied by grey-blue foliage that isn’t much of a color contrast in Summer—but it often flirts openly with burgundy in the Winter, whereas Yucca glauca holds to its blue year-round. Burgundy and blue: What garden doesn’t need more plant combinations and color pairings that are at their most vivid when it’s cold?

Yellow-needled junipers are the way to bring year-round contrast in color and texture. Juniperus conferta ‘All Gold’ is prostrate and low enough to be in front of the Yucca. J. chinensis ‘Gold Coast Improved’ is just a bit higher, so would be at the side. Choose just one or the other.

Yucca glauca will also grow in regular soil as long as the drainage is still good, in which case your additional choices are wide indeed. Can the Yucca be backed with dark green broadleaf foliage? Osmanthus or holly foliage is usually darker than that of box or rhododendron.

Because the Yucca is reliably evergreen, you can add deciduous and even herbaceous partners. I was once commanded to do a garden that featured pink, and wound up combining Yucca glauca with Spirea ‘Anthony Waterer’. Soapweed’s dangerous and blue foliage saved the bed from wallowing in soft textures and pastel colors.

About the only plants to avoid would be actual grasses, which would look repetitive at best, floppy at worst.

Where to use it in your garden

Yucca glauca is only happy towards the front of a bed, where its access to sun is minimally impeded. Its sculptural habit would be enhanced by planting into large pockets in ledge, or out of the way of traffic in a large sweep of gravel.

Full sun and soil that’s well-drained. The lax growth of my Yucca glauca shows how overly-moist my soil is—and, probably, that it’s also too rich. Yucca glauca looks better when the soil is lean and mean.

How to handle it: The Basics

Plant in Spring; water once and you’re done for the season. The plant can grow untended for years at a time, although you’ll want to clip off the flower stalks later in the Fall, by which time the yucca moth larvae have long since dropped to the ground, where they spend the Winter burrowed into shelter.

How to handle it: Another option—or two?

Yucca seems like a plant-and-forget-it plant, until you realize that there are a lot of brown leaves at the base that need to be clipped off. The foliage of Yucca glauca is so painful that this periodic maintenance needs some strategizing. The best tactic is to do it in late Winter, when it’s still so cold that you’d be wearing a reasonably heavy coat and gloves anyway.

Quirks or special cases

Yucca is long-lived, but any given rosette of foliage still has a life-span. After your clump is five or so years old, it’s not unusual for a rosette to take a pass on another year of rigid beauty. You’ll know by late Winter, so you can remove the deceased while still protectively garbed. If needed, free it from the colony by using your longest-handled loppers.

None. As is typical of Yucca species and cultivars, as long as the climate isn’t colder than each can tolerate—which would only happen with Yucca glauca if you were trying to garden near the Arctic circle—and the ground isn’t too poorly-draining, the plant is self-reliant and almost indomitable.

Yucca glauca is one of the less adventuresome of the many Yucca species, most of which seem to cross-pollinate as well as mutate casually, even opportunistically. Soapweed yucca has few cohorts, but I’d grow these if I could ever find them: ‘Stricta’ is more vigorous, with larger and branchier spikes of flowers; the flowers of ‘Rosea’ are tinted pink on the outside.

On-line and, occasionally, at retailers.

By seed, by division of the clumps, or by cutting the fleshy roots into sections in early Spring and placing them horizontally on the soil. They soon sprout leaves as well as roots.

Yucca glauca is broadly native to central North America, from Alberta and Saskatchewan to Texas, New Mexico, and Arizona.

A Gardening Journal

Yucca Glauca Care: Learn To Grow The Soapweed Yucca

Yucca glauca pronounced (YUK-ah GLOK-ah), belongs to the Yucca plant genus (Agavoideae) and family Asparagaceae.

It is a perennial evergreen plant, native to North America.

The plant is found in the rocky and deserted grassland ranges of the Great Plains, extending from the United States Arizona, New Mexico and Texas panhandle to Alberta and Saskatchewan in Canada.

Common Names include:

  • Small soapweed
  • Soapweed yucca
  • Great Plains yucca
  • Beargrass

Soapweed Yucca Glauca Care

Size & Growth

Yucca glauca, also known as soapweed yucca, growing from 3′ to 5′ feet high in USDA hardiness zones 3-10.

This narrow leaf yucca consists of a taproot from which rise small, decumbent branching stems.

This plant supports one or two large rhizomes from which a network of small slanting rhizomes arises, making an underground mat that can spread as far as 24″ inches.

Soapweed yucca has simple, alternate, curved-in pale green leaves with rough fibers running along its margins. Leaves can be as long as 8″ to 40″ inches in length and 0.2″ t0.5″ inches in width.

Flowering & Fragrance

Soapweed yuccas have white, pendulous, bell-shaped flowers about 2.5″ to 2.75″ inches in length, which are composed in clusters of 25 to 30 on a 12″ to 72″ inches long raceme.

At bloom time these flowers can only be pollinated by the yucca moth. In the absence of the moth, the plant needs hand pollinating, using a small paintbrush.

Yucca crowns produce several side shoots that can grow produce flower stalks later.

The crowns are monocarpic and die after flowering. The yucca flower fragrance is particularly acute at night.

Soapweed yucca also produces kiwi-sized oval, woody seed pods of dehiscent fruit which contain flat black winged seeds.

Light and Temperature

Soapweed yucca is a hardy native American yucca plant which can adapt to a wide range of temperatures.

It can survive temperatures up to 106 degrees Fahrenheit in summers and -42 degree Fahrenheit in winters.

The species can grow in bright sunlight, semi-shade or no shade at all.

It can withstand drought conditions very well and can even tolerate strong winds.

However, it does not thrive along coastal areas.

Watering and Feeding

Soapweed yucca has low watering needs, is drought tolerant and can easily survive dry seasons by spreading its roots deep underground to seek sources of water.

In bright outdoor settings, allow the top one-third of the soil to dry before watering.

In low light conditions, allow three-fourths of the soil to dry before watering.

If indoors, lightly sprinkle water to plant surface and place pebbles on top of the soil to prevent quick drying.

Soapweed yuccas prefer hot dry conditions with poor sandy and pebbley soil.

You can nourish your plant three parts coco-coir or peat and one part sand.

Feed indoor plants with a diluted mixture of liquid water-soluble feed in the spring and summer.

Soil & Transplanting

Soapweed yucca can thrive in most type of soils but prefers pebble-y, sandy loam with full sun exposure.

Plants are hardier when grown in soil with poor nutritional qualities.

This perennial plant does not tolerate peaty and chalky soils well.

In addition, the soil needs to be well-drained as overwatering can damage plant root systems.

It is best to pot smaller plants and grow them in light shade for two winters.

Then replant them out in the spring in their permanent year-round location in early summer.

Consider giving them some winter protection for at least their first winter outdoors.

Grooming & Maintenance

Like all desert plants, soapweed yuccas require only minimum maintenance.

Trim away dead leaves and flowers from time to time and wipe the leaves clean with a damp cloth.

If your plant has a lot of yellowing and withering leaves, it probably needs more water.

You may also like the Red False Yucca (Hesperaloe Parviflora) – it’s not really a Yucca at all.

How to Propagate Soapweed Yucca

Soapweed yucca can propagate through rhizomes and seeds.

Soapweed yucca rhizomes arise from established plants, which spread horizontally in a branching pattern.

Divide these yucca plants by cutting the rhizome. Dip the cut rhizome into dry wood ashes to stop the wound and plant it in a pot filled with sandy soil.

Rhizomes soon produce roots and sprout leaves.

Growing Glauca From Seeds

Pre-soak yucca seeds in warm water to reduce germination time, which can be anywhere between one month to a year.

Place the seeds into small pots, then prick the seedlings out and grow them in a greenhouse until they can grow well by themselves.

In Britain, flowers need hand-pollinating to produce seeds.

Soapweed Yucca Pest or Disease Problem

Soapweed yucca is not susceptible to many diseases though it may occasionally suffer from mealybug infestation and root rot.

Treat these with neem oil. Overwatering plants or allowing excess water to stay in the container can cause root rot.

Is the plant considered toxic or poisonous to people, kids, pets?

Great Plains yucca’s roots contain saponins. Although they are toxic to humans, our bodies cannot absorb them and they pass straight through.

Saponins are quite toxic to aquatic animals and hunting tribes used to dose river water with the substance to stun or kill fish.

Suggested Soapweed Yucca Uses

As the name suggests, soapweed yucca is used to make soaps and shampoos. Its dried leaves can be used to make sandals and woven baskets.

Its fruit can be baked into cakes, dried for later use or eaten immediately. It can be made into a delicious syrup that can replace hot chocolate.

The white inner portion of the stem can also be boiled and roasted and eaten like asparagus.

Being drought tolerant and its ability to handle a wide range of temperatures make the glauca yucca an excellent yucca plant for the landscape and for use as a xeriscape plant.

Yucca Glauca (soapweed) drought tolerant handles wide range of temperatures, pale green leaves, excellent for landscaping, and as xeriscape plant [DETAILS]