Cacti: They aren't just for deserts anymore

August 10, 2011 

It takes a desert to raise a cactus. Or does it?

At Tacoma’s Point Defiance Zoo & Aquarium a full blown – and often blooming – cactus garden is thriving alongside the meerkats and lemurs.

It seems like an oxymoron of gardening: a cactus garden in the soggy Pacific Northwest. Don’t these leafless plants need long days of scorching sun and drought-like growing conditions?

As zoo horticulturist Bryon Jones has discovered, the answer to both questions is no.

The garden just inside the main entrance to the zoo is now in its fourth summer. The long crescent-shaped space contains not only cacti but other arid zone plants. The backdrop for this unusual collection is a faux desert wall.

“Year-round this will stop people,” Jones says of the garden. “(There are) lots of questions about how to grow these.”

SPECIES

As antithetical as cacti may seem in the Northwest the desert areas of the Okanagan Valley are rife with the spiny plants and there’s even a species native to western Washington, Opuntia fragilis, found in the San Juan Islands. But Jones has gathered plants from far beyond the Northwest.

The plants in the zoo’s garden range from the Sonoran desert to Morocco to South Africa in origin. All of the cacti are from the Americas.

When it comes time to flower, one of the most striking species in the garden is Opuntia polyacantha, the prickly-pear cactus. The species occurs naturally from British Columbia to Mexico with numerous varieties flowering in eye-popping colors.

Another cactus, the cholla, is native to the Sonoran Desert. It raises its spindly frame along the garden’s wall. It bloomed in late July with magenta flowers.

While some plants in the garden are not cacti, they certainly fit the theme. Yuccas burst with their sword-like leaves radiating from a central stalk. Jones has planted several varieties ranging from purple leafed to one with white margins on its leaves (Yucca aloifolia Variegata).

Agave parryi truncata (the artichoke agave) is a low growing rosette of spike-tipped leaves in the zoo’s garden. Its well-know cousin, the blue agave, is the source of Tequila (but absent from the garden.)

One ground hugging specimen, ice plant, is a succulent with neon magenta flowers. Some kinds of ice plant have become highly invasive along California’s coastal dunes, but the zoo’s species (Delosperma cooperi) maintains its manners.

While many plants in the garden look foreboding, some are delicate and lovely. Asphodeline lutea (King’s Spear) has long stalks with yellow orchid-like flowers followed by big green seed pods looking not unlike a cluster of grapes.

Fabiana imbricata is a six-foot tall bush with pinkish-lavender flowers and tiny leaves. Another bush, the bottlebrush (Callistemon) from Australia, has bright red frilly and, yes, brush-looking flowers.

Jones uses many varieties of Salvia (sage) – a genus with hundreds of species that does well in arid settings. The variety ‘hot lips’ has tiny white over red flowers.

Despite the success of Jones’ work not all desert species can grow in the Northwest. You won’t see Arizona’s multi-limbed Saguaro, arguably the most iconic of all cacti, anywhere near Puget Sound.

BENEFITS AND DRAWBACKS

Fans of xeriscaping (landscaping without supplemental watering) will love the zoo’s water-frugal plantings. Jones only waters the garden for five minutes, once a week. New arrivals may need more water in the first two years after planting, but after that they are on their own.

Many arid plants have aromatic qualities. To demonstrate, Jones took a sprig from a woolly tea tree (leptospermun) and rubbed the red stems and small leaves in his fingers. The fragrant odor filled the air with spice.

There are some drawbacks to the garden, most noticeably that so many of the plants have painful needles, spikes and spears. A visit to the acupuncturist would seem like a spa treatment after a run-in with some of these plants.

“You’ve got to watch what you touch around here,” Jones said as he carefully stepped between the plants while keeping track of all his limbs.

GROWING CONDITIONS

The setting for the zoo’s garden is almost perfect for the plants that grow there despite the feet of rain that fall in the wet season. Its many features serve as a guide for the home gardener.

 • Jones used sandy loam as soil for the garden. The soils provides nutrients as well as drainage.

 • The gently sloping terrain allows for easy runoff. While arid zone plants can survive the rains of the Pacific Northwest, they don’t like standing water.

 • The garden setting faces south for maximum sunlight. No trees to create shade, a killer for these sun loving plants.

 • A rocky mulch suppresses weeds, reflects heat and conserves moisture in hot months. The zoo’s wall also reflects heat – an effect that could be duplicated by walls, fences and rocks.

There have been some fatalities. Jones lost a couple of plants that were planted close to a storm drain. He speculates the excessive water did them in.

And what about snow? Not to worry, says Jones. “Snow is a positive. It acts as an insulator.”

The plants in the zoo’s garden are given space between each other. This not only reflects their natural growing conditions but provides airflow between the plants, even more crucial in the moist Northwest.

The cacti and their brethren use only the barest amount of fertilizer and need little care, Jones said. “Anybody can grow them.”

Craig Sailor: 253-597-8541 craig.sailor@thenewstribune.com

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