In the Garden Articles

Spiny Succulents

by Joan S. Bolton

Beauty and the Beast.

Both labels describe our native spiny succulents, which are a perfect study in contrasts. On the one hand, these prickly plants advance beastly spines. On the other hand, they bear incredibly beautiful flowers.

When you examine them up close, their fearsome features are oddly alluring. And they're sensible additions to water-conserving gardens, serve as barrier plants and offer protection and sustenance to wildlife.

Barbarians at the Gate

So what are spiny succulents? Botanical consultant Stephen Ingram spent four years traipsing 30,000 miles across California and Nevada to investigate more than 60 native species. They include such familiar types as prickly-pear and cholla, along with relative rarities like golden cereus and desert pincushion.

In his new book, "Cacti, Agaves, and Yuccas of California and Nevada," published by Cachuma Press, Ingram examines each, and takes a naturalist's view in describing how these formidable plants have evolved in often harsh and forbidding environments.

He offers up some remarkable traits.

For instance, it's commonly know that spiny succulents store water in their leaves to tolerate bone-dry conditions. But Ingram tells us they can lose 70 to 90 percent of their water volume and survive, while most plants die after losing just 30 percent. A waxy, outer layer traps moisture, while bumpy tubercles and vertical ribs expand and contract based on how much water is available.

They set photosynthesis on end.

Most plants open up their stomata -- the pores on their leaves or stems -- during the daytime to take up carbon dioxide (CO2) and convert it to the sugars and starches they need to live. But according to Ingram, all of our native cacti and most of our agaves photosynthesize at night, when the relative humidity is higher and they won't lose as much water vapor.

When it does rain, cacti, agave and yuccas grow fine, shallow "rain roots" to grab moisture from the surrounding soil. Ingram notes that barrel cactus can increase their root area by more than 25 percent after a heavy rain.

Critter Friendly

While we humans most certainly sidestep spiny succulents, they offer safe haven and nourishment to bees, birds and other animals.

Over 20 species of cactus bees specialize in pollinating the flowers.

"The prickly-pears -- coastal prickly-pear and tall prickly-pear -- have these stamens that will move in. When a bee or a beetle goes there, wallows around and starts eating the pollen, the stamens will close in and dust the insect with pollen," Ingram says. "You can stick a finger or a pencil in on a warm day and watch that happen."

Birds dependent on our spiny succulents include Scott's orioles, which weave nests on Joshua trees. Cactus wrens make their homes in chollas. Woodpeckers hollow out dried stalks of chaparral yucca and saguaro. Phoebes and flycatchers abound. And loggerhead shrikes use sharp edges to kill their prey.

"These so-called 'butcher birds' catch large insects, small birds, and lizards and impale them on a nearby thorn, cactus spine, or Joshua tree leaf, returning later to feed," Ingram says.

Other wildlife include desert packrats, which arm their dens with cholla and prickly-pear, and assorted moths, hummingbirds and nectar-feeding bats that sup from and pollinate the plants.

In the Garden

Growing spiny succulents on the Central Coast can be tricky. Our late-spring and summertime fog, coupled with cold, damp winters, can be the kiss of death.

However, there are half a dozen species native to Santa Barbara County, and Ingram says all should do well here.

"They do tolerate quite a bit of neglect. For certain gardeners, they are nice to grow."

Our locals include four prickly-pears, two chollas and a yucca.

Coastal prickly-pear (Opuntia littoralis) is a low spreader, forming dense thickets across coastal bluffs. It blooms in bright yellow in May and June.

Tall prickly-pear (Opuntia oricola) looks similar and blooms in yellow, too. But it grows up to 8 feet tall and its summer-time fruit have a much deeper depression on their tops, where the flowers have fallen off.

Brown-spined prickly-pear (Opuntia phaeacantha) bears gold flowers that are red at the base. Its new spines are also red at the base, pale brown or white at the tips and mature to a dusky gray. In winter, when production of green chlorophyll pigments slows down, its pads take on a purplish tint.

Western prickly-pear (Opuntia Xoccidentalis) is a naturally occurring hybrid that botanists believe is some combination of coastal prickly-pear, Engelmann prickly-pear, brown-spined prickly-pear and tall prickly-pear. It has fewer spines at the base of its long pads and there's a green stigma at the center of each yellow flower.

Oddly enough cane cholla (Cylindropuntia californica var. parkeri or Opuntia parryi) is not a desert plant. Instead, it thrives in inland chaparral, valley grasslands and oak woodlands. Pale yellow flowers bloom at the upward-facing tips of the thick, spiny stems from April to July.

Coastal cholla (Cylindropuntia prolifera or Opuntia prolifera) forms a dense clump and bears flowers in an unusual shade of pink to reddish, purplish brown in late spring or early fall. Also known as jumping cholla, its spines are tenacious.

Chaparral yucca or our Lord's candle (Hesperoyucca whipplei or Yucca whipplei) is a familiar sight on steep, coastal hillsides, where it forms single, grass-like clumps, then sends up a statuesque spike of cream-colored flowers.

It's a wonderful single-specimen plant in the garden, where its stiff leaves provide a contrast to neighboring, mounding forms. It dies after blooming. But it often produces offsets, so you can always have more.

Beyond our local natives, Ingram says Shaw agave (Agave shawii var. shawii), beavertail cactus (Opuntia basilaris var. basilaris) and coastal barrel cactus (Ferocactus viridescens var. viridescens) are garden-worthy subjects for Central Coast gardens.

In addition, Indian-fig cactus or mission cactus (Opuntia ficus-indica) is a robust grower. It's been used for centuries around missions and ranchos for food and as a barrier plant. Ingram notes that the mucilage, a slimy substance produced in the plants' cells, was used to bind adobe bricks. Currently, he notes, it's cultivated on five continents. Its fruit is harvested for food, drink and medicinal products.

What It Takes

The key to success with spiny succulents is drainage, drainage, drainage.

"These plants are pretty versatile. If people have the right conditions, they can grow a lot of these things," Ingram said. "The thing is keeping them well drained, and not real damp and wet when it's cold out."

That means shielding the plants from rain if there's any likelihood that pudding will occur. Ingram says some folks plant their spiny succulents beneath their eaves. Even better is planting them in pots, where you can control the soil mix and move them out of the rain.

In addition, he says they'll do best in sun. But don't plant the larger ones next to a pathway, where someone might end up on the wrong side of a spine.

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Handle With Care

Spiny succulents are tough customers when it comes to planting them in the ground or transplanting them to a larger container.

If your plant is small, use chopsticks or salad tongs to move it. If it's larger and mere gloves won't do, use heavy-duty fireplace gloves. Or wrap up the plant in layers of newspaper or plastic bubble wrap.

Once your specimen is in the ground, weeding will be difficult.

Before planting, thoroughly weed the area. Then lay down weed cloth, cut an "X" in it and roll back the edges. Dig your hole, plant your plant, then smooth the edges into place.

Mulch the area with gravel, rocks, decomposed granite or decorative glass stones. Avoid bark or organic mulch, which will retain moisture for longer than your spiny succulent may like.

In the ground, botanical consultant Stephen Ingram recommends applying a dilute liquid fertilizer one or twice from spring through early fall.

In containers, where nutrients leach out more quickly, Ingram advises fertilizing more frequently.

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Seeds of Wisdom

The shimmering colors of cactus flowers attract pollinating bees. The iridescence is due to rare betalain pigments that produce the brilliant red, pink, orange and yellow hues. Those same betalain pigments give bougainvillea, iceplant, portulaca and dianthus their radiance.