Gardening : Ultimate Water Misers for Indoor Gardener : Cacti: They and succulents are gaining popularity because of their unthirsty habits and compatibility with Southwestern decor.

While Southern California’s outdoor gardeners search frantically for ways to save their landscapes during these endless rainless days, indoor gardeners have found the perfect solution to growing plants and still conserving water:

As their old and fading foliage plants die, houseplant lovers are replacing them with the ultimate drought-resistant plants--cacti and succulents.

Although cacti and succulents have been very popular as houseplants for decades, nursery people report that the ongoing drought and the trend toward Southwestern decor haveincreased their popularity tremendously the last couple of years.

There’s surely a cactus or succulent to suit every taste among the thousands of species and tens of thousands of varieties, and many of them are very easy to cultivate indoors.

Perhaps the greatest virtue of cacti and succulents as houseplants is their ability to live in spite of even the most severe neglect. As long as a cactus or succulent is placed in a bright sunny window--a southern or western exposure is best--it will thrive with virtually no other care.

Cacti and succulents are separate families of plants, but both are succulent--they store water in their leaves and stems, making it possible for them to go months, in somecases even years, without water.

Their ability to withstand neglect is a byproduct of their evolution in the deserts of the Americas, where, besides a lack of water, they’re required to weather fiercely hot days and near-freezing nights.

Another bonus benefit of growing cacti or succulents is that they all produce beautiful, vibrant flowers once every year if cared for properly.

To bloom, cacti must be kept in bright sun, kept warm during the day, and be afforded long, cool--even cold--winter nights. Depending upon the species, cacti generally bloom for one or two months from March through August.

If you would like to see a truly amazing array of cacti and succulents, I suggest you visit Maleenee Desert Gallery at 216 S. Rosemead Blvd., Pasadena.

Maleenee, which is operated by Molly Thongthiraj, was founded by her grandparents 40 years ago and has been the family business every since. There are more than 15,000 plants at the nursery, all grown by the Thongthirajs, and there are always thousands more in various stages of development growing on the family’s 25 acres of land near the Salton Sea.

Over the years the Thongthirajs, who started raising cacti and succulents as a hobby, have grown and sold millions of desert plants, but they still love what they do and it shows in the quality of their cacti and succulents.

As you wander up and down the aisles of the carefully manicured greenhouse, you’ll see near-perfect specimens of almost every variety of succulent plant imaginable, including barrel cactus, echeverias; old man cactus (Cephalocereus senilis), jade plants, Lithops (living rocks), opuntias, aloes, kalanchoes, haworthias and euphorbias.

One reason the Thongthirajs plants are so flawless is that most of them are grown from seed, as opposed to cuttings.

“When you grow from seed you not only get more plants, you get cleaner plants,” Thongthiraj said. “Most people--especially collectors--want their plants to be free of scars, so even though it takes longer to grow a plant from seed we feel it’s worth the extra time.”

According to Thongthiraj, it takes about three years from the time a cactus seed is planted until it’s large enough to market in a 4-inch pot. “Most people buy the 4-inch or 6-inch plants for indoors,” said Thongthiraj, “but we sell lots of the larger, tree-like plants as well.”

The 4-inch plants range from $2.99 and the 6-inch plants begin at $6.99. The most expensive plant at Maleenee is a 5O-year-old aloe bainesii--a giant tree valued at $10,000. The nursery’s best seller is the African milk tree (Euphorbia trigong)-- a beautiful smooth-skinned succulent whose cactus-like shape is virtually a symbol for “Southwest.”

Not far behind are the various opuntias, the most familiar of those being what I call the “Mickey Mouse” varieties (the ones with the large, round “ears”), followed by kalanchoes and echeverias, my particular favorites. There are almost 200 different varieties of echeverias available, including many new hybrids with white, pink, purple and even striped rosettes. These include E. truffles, E. cinderalli and E. Arlie Wright.

Exotic and unique grafted cacti are also highly favored by Southland cactus fanciers. The most familiar example of a grafted plant is the ubiquitous “moon cactus”--the cacti with little red or yellow heads sitting atop a thick, green stalk.

Contrary to common belief, these plants don’t grow that way. They are, in fact, one cactus grafted onto another. (The red moon cactus, for instance, is a Gymnocalycium mihanovichii grafted onto a trichcereus variety.)

Maleenee has a large selection of grafted cacti, all made by Molly Thongthiraj’s sister, Sammy, at the family’s Monrovia greenhouse.

“Sammy can make hundreds of grafts a day,” said sister Molly, pointing out that any cactus can be grafted onto any other cactus, but you can’t mate a succulent and a cactus.

Depending upon the size and variety, grafted cactus can become a bit pricey, but the good news is it’s inexpensive, easy and fun to make one of your own.

To make a grafted cactus, get two cacti, one of which will become the bottom portion (this is called the “stock” plant--any columnar cactus will do)--and the other, which will become the top.

Making sure to wear heavy gloves, use a sharp, sterile knife and slice the top off your stock plant. Then slice the tip off the plant that will become the top. Align the center core of both plants, and then place the top cactus firmly onto the stock plant. Secure the two pieces with a rubber band or two, and within two to three weeks the graft shouldtake and the two plants will be wedded.

During these two or three weeks, the plant can be watered if needed but, warns Thongthiraj, be careful not to wet the top. And, she adds, only graft during the warmer spring and summer months, not during the cold of winter.

Succulent plants should be fed with a liquid houseplant food every other week, and should be grown in a mixture of equal parts coarse sand, pumice, peat and perlite, If you don’t want to bother to make your own, sterilized cactus mixes are available almost everywhere plant supplies are sold.