Home >  Lifestyle >  Homes

Saturday, January 18, 2003

By Georgia Wahl, Phipps Conservatory and Botanical Gardens

With a wide variety of brightly colored flowers on easy-to-grow plants, dendrobiums are one of the easiest and most popular orchids to grow in the home.

An Epicattleya viola 'Katherine' is part of the display at Phipps Conservatory's "Orchid Inspiration." (Steve Mellon, Post-Gazette) Growing with Phipps This is one of a series of periodic columns by staffers of Phipps Conservatory and Botanical Gardens. Georgia Wahl is orchid manager for Phipps. Previous installment Limit winter watering of homegrown cactus Related articles Flower Show Preview: Inspired by Orchids Phipps offers gardening classes

With more than 1,500 species, dendrobiums make up the second largest and most complex genus of orchids. They grow naturally in a great variety of climates, from areas of regular heavy rains to areas that have periods of drought. They can be found in many places, including western Asia, Australia, New Zealand, China and Japan.

Most are epiphytes, plants that get their moisture and nutrients from the air. In nature, these plants grow on another plant for support but are not parasitic, as they do not draw any nutrients from the host plant. Their stems, called pseudo-bulbs, range in size from miniatures of only a few inches to giants of 15 feet. Some species are deciduous and others are evergreen.

Dendrobiums like bright light, preferably near a west or south window. If you have one that looks healthy but won't flower, try moving it to a brighter spot. Since most dendrobiums tend to be relatively tall, it can be hard to grow them under artificial lights.

As is the case with most orchids, dendrobiums prefer to be grown in a medium that drains quickly. The best is a medium-sized fir bark mix that has been developed specifically for use with orchids. Sometimes additives such as charcoal, perlite and sphagnum moss are also used. Many growers have their own particular recipes, but generally a mixture of about 10 parts bark to one part perlite and one part charcoal works well. Pre-made mixes can be purchased where orchids are sold.

Dendrobiums can be divided just like many other plants. The best time is when new growth has begun and new roots are showing. When dividing, be sure to leave at least three to four stems (also called canes) in each division. Another method of propagation is to pot up the little plantlets that develop on the ends of older canes. These are called keikis, a Hawaiian word meaning "little plants." A third method is to cut up older canes between the nodes and place them on damp sphagnum moss that is kept moist. Most dendrobiums prefer to be underpotted (planted in relatively small pots), as their roots tend to be short, thin and wiry.

Generally dendrobiums can be grown at normal room temperatures of 70-90 degrees. But there are exceptions, especially with species plants (non-hybrids). Some may require cool winter rests, some need dry conditions, others wet. "Dendrobium and Its Relatives" (Timber Press, $39.95) is one of the many books that have specific cultural information for your orchid.

Like most epiphytes, dendrobiums grow in regions that have moderate to high rainfall. They like to be watered heavily during their growing periods, but watering should be cut back when canes reach full growth. Resume watering when new growth appears and has begun to make roots. Dendrobiums can flower several times a year if cared for properly. They also will flower on older canes, even if they have lost most or all of their leaves.

As with other orchids in bark, dendrobiums like a constant feeding during their growing season. It is best to use a weak solution (half the recommended strength) on a regular basis (perhaps weekly) rather than to use a full-strength solution once a month. Any balanced fertilizer, such as 18-18-18 or a 20-20-20, should work.

It is difficult to recommend specific hybrids, as there are so many new ones every year. Dendrobiums are generally considered easy to grow at home, but it is always best to know which type of dendrobium you have so you can find out what temperatures it requires and whether it needs a cool or a warm rest, if any at all.

Visit Phipps orchid room all year long to see many beautiful orchids in bloom. For answers to questions about orchids and other plants, call Phipps' GreenLine at 412-665-2364.

Phipps Conservatory and Botanical Gardens is offering a series of gardening classes at Phipps Garden Center, 1059 Shady Ave., Mellon Park.

Beginning Wednesday, horticulturist Susie Lobdell will teach a course called "Home Landscaping 101" from 10 a.m. to noon. Students will learn how to read and create landscape drawings, build borders and flower beds and choose proper plants to avoid future problems. The classes continue Jan. 29 and Feb. 5 and 12. Cost: $64 for members, $74 for nonmembers.

Beginning Thursday and continuing Jan. 30 and Feb. 6, horticulturist Ray Saber will lead "Constructing Walls, Walks and Patios" from 7 to 9 p.m. Cost: $48 for members and $68 for nonmembers.

Other courses are also available. For more information or to register, call 412-441-4442 or go to www.phipps.conservatory.org.