It started out as an innocent hobby. Ken and Deena Altman were fresh out of graduate school: Ken with a PhD in psychology and Deena with a degree in human development. The two had been growing cactuses in their backyard and found they had more plants than they had garden.
So they began selling their overstock to local nurseries. Then they entered the mail-order plant business. That was 25 years ago. In a true story of avocation becoming vocation, the couple now runs Altman Plants, a large plant supply and distribution business with several hundred acres of greenhouses and growing grounds in several states.
The Altmans supply roughly 50 percent of the retail cactus market in the US.
Though their plant repertoire now includes perennials, vegetables, herbs, and other plants, cactuses remain one of their main product lines.
"I love cacti," says Mrs. Altman. "Their structure, the geometry of the plants.... I really enjoy their bloom in the spring. To me, they are like living treasures. Each plant is a little living gem."
What makes a cactus a cactus? A botanist will tell you that cactuses are a special group of succulents native to the Americas. They have spines that emerge from special tiny round organs known as areoles. Cactus flowers are large and either white or fluorescent shades of yellow, orange, and pink.
Spines, of course, are a cactus's most distinctive, though most variable, feature. Spines can be small and silvery - or large and tough enough to be used as fishing hooks and sewing needles.
Interestingly, cactus spines are actually modified leaves. Why do these plants have spines? Experts think that spines protect them from hungry predators and shade them from intense sun. Spines also create buffer zones around the bases of the plants, reducing evaporation and directing precious dew toward the roots - an important function in hot, arid deserts.
Deserts, however, are not the only places where cactuses grow. There are cactus plants native to jungles and islands, and from sea level to the mountains. Their shapes and forms are as varied as the habitats they grow in.
In an effort to simplify things, growers categorize cactuses according to their shapes and growth habits:
Columnar cactuses have tall, cylindrical stems. Some, like the famous saguaro cactus (Carnegiea gigantea), grow more than 50 feet tall and form candelabra-like branches.
A barrel cactus is thick and spherical with heavy ribs. It grows from 1-1/2 to 6 feet tall. Golden barrel cactus (Echinocactus grusonii) is common in landscapes of the Southwest.
Pincushion cactuses are spherical or cylindrical. They tend to be less than a foot tall, solitary or clumping.
Opuntias come in two general forms: flattened pads that look like thick leaves but are actually flattened stems, and jointed, sausage-shaped stems.
Epiphytic cactuses grow on other plants rather than in the ground. Epiphyllum, known as orchid cactus, is one type.
You needn't live in southern California, or even in the Southwest to grow cactuses. In fact, they're native from Alberta, Canada, to Argentina, and east to the Caribbean.
With a bit of knowledge and a sense of adventure, you can grow cactuses almost anywhere, both indoors and out.
Don Martinson grows them near Milwaukee, but he does it in pots. In the fall, he moves them into his basement, where they overwinter on windowsills. The temperature of Mr. Martinson's basement ranges between 50 and 60 degrees F, about the same winter temperatures that his plants would experience in their native habitats.
Keeping cactuses dry enough is a special challenge for Martinson. "Here in Wisconsin, we can get rainy, damp weather virtually any time of the year," he explains.
"If some species don't get a chance to dry out, they easily turn to mush," he says.
Martinson plants his cactuses in a very free-draining potting mix to ensure that they dry out between waterings.
In an area of Tennessee where winter temperatures occasionally flirt with zero, Nancy Robinson has grown cactuses in the ground for 30 years. She grows mostly opuntia, the prickly pear cactus, which does well in the open, sunny areas of her garden.
Like Martinson, Ms. Robinson works hard to make sure her cactus plants have good drainage. Early on, she amended her soil with generous amounts of sand and gravel for water to drain through.
Growing cactuses as houseplants isn't difficult, these experts say. Place your potted cactus in a very sunny windowsill, in a greenhouse, or outdoors during the warm months and indoors in the winter.
Overwatering can mean death to a cactus. Mrs. Altman recommends watering cactuses thoroughly each time you water (that is, until water comes through the drainage hole in the bottom of the pot).
When the plants are growing - roughly March through September - allow the soil to dry out at least one inch beneath the surface before you water again.
If you are uncertain about watering, don't do it. Wait a few more days.
From October to February, cactus plants go dormant and don't need much water. Allow the soil to dry two inches below the surface before watering.
Indoors, place a potted cactus in your brightest window. If, after awhile, the cactus elongates in an odd way, it is telling you that it is not getting enough light and needs to be moved.
If you move cactuses outside in the warm months, take your time acclimating them to sunlight. First move them to a fairly shaded location. Over the course of a week or more, move them into brighter and brighter light. Keep potted plants out of full-day sun, even once they are acclimated.
Starting in February, fertilize potted cactuses with half-strength fertilizer once a month. To promote spring bloom, use a high-phosphorous fertilizer (the middle number will be the largest of the three numbers on the container; 5-10-5, for instance).
After a cactus has bloomed and until it goes dormant again in October, switch to half-strength balanced houseplant fertilizer each month (one on which all three numbers are equal; 20-20-20). Stop fertilizing once October rolls around again.
To repot a cactus, turn the pot on its side onto a few sheets of newspaper. Tap the side of the pot to loosen the plant. Notice the soil line on the side of the plant. - when you replant the cactus, plant it only up to the soil line.
To move a large plant, wrap a hose around its base, or roll up a thick newspaper to wrap around it. You might want to wear gloves.
Unglazed terra cotta is the best kind of pot to use for cactuses if you tend to overwater.
Use regular potting soil amended 30 to 40 percent with perlite or pumice, both of which increase air spaces in the potting mix and improve drainage. Top the soil with a layer of rock or gravel mulch if you like the look, or if you have a cat that likes to dig in your pots.
Cactuses are some of the easiest plants to propagate, especially segmented ones and those that form new plants (pups) at the base of the plants.
Look for the narrowest point at which the pup or segment attaches to the parent plant. Use a sharp knife to cut it off, then dust the cut surfaces with sulfur to guard against rot. Allow the cutting to dry for three or four weeks before potting it up. Bury the cutting in a pot of soil only deep enough to keep it from falling over. Place the new plant in a shady location while it roots.
The best time to take cuttings is in late spring when plants are entering their active growing season.
Deena Altman of Altman Plants recommends the following cactuses for new growers:
Ladyfinger cactus (Mammilaria elongata). A low-growing cactus with pale yellow to pinkish flowers that become pink or red fruit. Plants are only an inch or so in diameter, but grow in clusters. Spines are tiny and needle-like, white to golden yellow.
Old Man Cactus (Cephalocereus senilis), which is named for its long, white, hair-like spines. These columnar plants grow slowly up to 50 feet tall and 12 inches in diameter. Funnel-shaped flowers are yellowish-pink, about three inches long and three inches across. It needs little to moderate water in summer and almost no water in winter.
Golden barrel cactus (Echinocactus grusonii). A solitary plant, slowly growing to four feet high and three feet or more in diameter. Its distinctive golden spines darken with age. It has two- to three-inch yellow flowers in spring.
Rhipsalis is a group of more than 60 tropical jungle cactuses. These plants are generally spineless, with long, dangling stems that make them perfect for hanging baskets. Flower color varies.
Angel's wings, prickly pear, or beaver tail cactus (Opuntia microdasys). A popular houseplant and patio plant native to Mexico, it grows slowly to three feet high and six feet across. The plant is shrubby with flat "beaver-tail" stems dotted with clusters of tufted yellowish spines. Its yellow flowers appear mostly in summer. This cactus prefers light shade or only morning sun.