Home >  Lifestyle >  Homes

Saturday, January 11, 2003

By Curt Pesanka , Phipps Conservatory and Botanical Gardens

Cactuses make wonderful, easy-to-care-for houseplants that require very little from you, especially in winter. Because they are succulents, they store water, allowing them to survive dry periods. In fact, they even require them. If you don't "kill them with kindness," they will thrive.

	Christmas cactuses are native to the tropical forests of South America, but they are easily grown inside Pittsburgh homes. (Steve Mellon, Post-Gazette) Growing with Phipps This is one of a series of periodic columns by staffers of Phipps Conservatory and Botanical Gardens. Curt Pesanka is horticulture foreman at Phipps.

Watering

Most cactuses need a dormant period during winter. This prepares them to bloom next spring or summer. During the dormant period, they should be watered sparingly, if at all. From November to March, most cactuses should be watered only when they begin to shrivel slightly.

There are exceptions. Thanksgiving cactus (Schlumbergera truncata) and Christmas cactus (Schlumbergera x buckleyi) originate in the tropics of South America, where they grow as epiphytes. Epiphytes are plants that grow naturally on other plants, using the host plant only for support. They may root in moist plant debris that collects in the nooks and crannies of other plants or get moisture from the air.

Since they are native to tropical forests, epiphytical cactuses need more moisture and higher humidity than other cactuses. But they are still very easy-to-grow houseplants.

Light

Most cactuses need bright light year round. A location near a cool, southern window is perfect. Epiphytes can take less light, but they will bloom best in a bright location.

Fertilizer

Cactuses should not be fertilized from September to March. When new growth appears in early April, you can begin applying a balanced liquid fertilizer at half the strength recommended.

Temperature

Most cactuses like daytime temperatures between 59 and 86 degrees, with minimum night temperatures between 50 and 59 degrees. When they're dormant, temperatures ideally should be between 45 and 50 degrees. Tropical species (epiphytes) enjoy daytime temperatures between 70 and 90 degrees, with minimum night temperatures between 55 and 68 degrees and, during dormancy, 50 to 59 degrees. Fortunately, cactuses should still do well in your home even if your nighttime temperatures do not drop that low.

Plants to know and grow

The hardy Opuntia humifus, commonly known as Bunny Ears, will grow and thrive outside in well-drained soils where it receives at least four hours of direct sun. During the winter months, the ears deflate and look dead, only to pump themselves back up in late spring. Bright yellow flowers adorn this plant in the summer.

The Saguaro (Carnegiea gigantea) is familiar to most people. It can grow to 60 feet in its natural environment, but it takes up to 30 years to grow 3 feet tall when it's grown as a houseplant.

Other favorites include Golden barrel cactus (Echinocactus grusonii) and Mammillaria, a low growing cactuses with beautiful long-blooming flowers in many different colors that arrange themselves in a circular pattern near the top of the cactus. The epiphytic cactuses have beautiful, bright flowers in shades of pink, red, orange and white.

In the Desert Room at Phipps, you will see these plants and many other interesting specimens, including a Saguaro cactus that is more than 60 years old and a type of Prickly Pear cactus that looks like a tree. Try growing a cactus near a bright window in your home.