Dennis Bottemiller, with the laid-back and friendly mannerisms reminiscent of a surfer, is really into rhododendrons. He grows about 70,000 of them each year.

Bottemiller spends his days as the nursery manager and "Propagator" for the Rhododendron Species Foundation and Botanical Garden (RSBG) in Federal Way, a non-profit organization existing solely for the conservation, acquisition, research, display and distribution of the showy evergreens.

Maneuvering around long tables full of starter trays in a new high-tech greenhouse, Bottemiller tends the seedlings and cuttings destined for mail-order plant sales, or perhaps a featured spot amongst the center's 22 acres of 10,000 members of the genus Rhododendron, which includes azaleas.

"They need a little coddling the first year, but once they are established, most rhodies are pretty easy to take care of," said Bottemiller, motioning towards his throng of tiny progeny, all at different growth stages.

Besides Washington's state flower, Rhododendron macrophyllum, there are over 1,000 identified rhododendron species around the world; visitors to the RSBG will see around 488 different types, ranging from the dwarf alpine R. forrestii to the towering R. rex fictolacteum. In between are an astonishing array of colors, leaf and flower shapes. The gardens offer the largest collection of rhododendrons in North America.

"People come here to see a lot of very rare plants, ones they won't find elsewhere in North America," said Steve Hootman, co-executive director and curator of the Rhododendron Species Foundation.

Hootman knows where to find rare rhodies. His coworker Victoria Clingman describes him as "our own Indiana Jones," as Hootman frequently travels to insanely remote places around the globe to gather seeds and occasionally "discover" new species. Since rhododendrons flourish all over Asia (particularly in the Himalayas - R. arboreum is Nepal's national flower), North America and Europe, Hootman's passport is well worn.

This year, the Rhododendron Species Foundation began publishing a new annual "Yearbook" featuring the latest taxonomic studies and a comprehensive catalog. In the inaugural 2006 edition, Hootman recounts his recent daring trek to Mount Saramati in Nagaland, an isolated and forbidding region on the border of northeastern India and Burma, searching for the elusive and extremely rare rhody, R. wattii. Braving monsoons, snakes, leeches, tigers and rebel armies, Hootman and his companions spent five weeks hiking a vast area. He never found R. wattii, but came home to Federal Way with pictures, seeds and cuttings from hundreds of other exotic varieties. Hootman's fieldwork keeps the RSF at the forefront of rhododendron research and cultivation.

Once back at the RSBG, Hootman hands over his flora booty to Bottemiller's nursery. A recent development at the foundation was the construction of a new greenhouse, which, to the untrained eye, looks like any other greenhouse. It's not. Equipped with a sophisticated weather station on the roof that constantly monitors light duration, temperature and barometric pressure, the whole structure is lined with a mechanized curtain of mesh material that moves back and forth to keep light conditions optimal for the young rhodies. Embedded into the tables under the starter trays are hoses conducting hot water, and ever few feet are sprinklers emitting a finely controlled mist.

After spending an appropriate amount of time in the nursery, the foundation's stock moves into the care of Kurt Looser, the head gardener. Looser retired from the U.S. Coast Guard and became increasingly enchanted with horticulture while landscaping his home. He decided to pursue a second career, enrolling in a one-year environmental horticulture program at Lake Washington Vocational Tech in Kirkland. He joined the staff fulltime in July of 2004 after serving as an intern and patiently waiting for a vacancy.

Looser's chief duty is the maintenance of the botanical garden acreage open to the public.

Growing in between all the rhodies are tons of "companion" plants such as ferns, heathers, conifers, iris and magnolias. There's a large pond sporting aquatic and bog plants, an alpine rock garden made from 200 tons of granite from the Cascades and a lavish gazebo made from a single Western red cedar donated by Weyerhaeuser.

"There is a lot going on here," said Looser with a contented grin. "It's a very satisfying place to work, I'm always learning."

Looser, the other four staff members and a score of dedicated volunteers also focus a lot of attention on catalog sales.

As a non-profit, the foundation and gardens are partly funded by the thriving mail-order business; the proceeds from these sales go directly back into the operating budget. Orders are processed in the shipping room, a long hoop house connected to the greenhouses.

"We used to send out many more orders overseas, but over the last decade the EU and other countries have tightened biological security. One root ball might host millions of microbes, fungi, etcetera, which might do significant harm elsewhere," explained Bottemiller. "There is no way to send a "clean" plant." These days most of their orders are shipped out to the East Coast and Canada.

The RSBG is adjacent to the Pacific Rim Bonsai Collection, which is owned and operated by Weyerhaeuser. Although the RSBG is a separate entity, visitors come to see both attractions.

In 1974, Weyerhaeuser offered a total of 24 acres to the Rhododendron Species Foundation, at no cost, located on the company's corporate headquarters campus in Federal Way. For ten years prior to 1974, the RSF existed as a group of American Rhododendron Society members in Oregon.

With a permanent collection site established, the foundation started a membership program in 1976, and currently boasts 750 members from 15 countries. Today the Rhododendron Species Foundation is supported by the memberships and the mail-order business, as well as gate receipts, grants, donations, annual spring and fall plant sales, and sales from the gift shop.

A membership with the Rhododendron Species Foundation includes free year-round garden admission, the annual yearbook, discounts on plant sales and use of their on-site horticultural library.

Non-members pay a $3.50 entrance fee (seniors and student, $2.50, under 12 and school groups get in free).

For more information, visit www.rhodygarden.org or call 253-661-9377.