John and Jeanne Hess of Redmond took home armloads of bee balm (Monarda didyma), crocosmia, hostas, Joe Pye weed (Eupatorium purpureum) and yellow foxglove (Digitalis grandiflora) for the grand total of: Free.

"Why don't you take this, too?" said Rev. Jim Eichner, handing over a clump of phlox, which he said would bloom hot pink. The rector of Redmond's Episcopal Church of the Holy Cross, which hosts the twice-a-year Eastside Green Elephant Plant Swap, Eichner stayed busy trading and dispensing plants and advice with 25 or so other gardeners.

"We're beggars today," said John Hess, who moved here from Michigan a year ago. "Our back yard is just bare. Maybe next year we'll have something to exchange."

First-timer Carolyn Sanscrainte of Seattle, who took away several clumps of bareroot hostas — including chartreuse and blue-green varieties — told Eichner she hoped she wasn't being "too greedy."

He shrugged and motioned at the collection of roots, clumps and twig-like plants. "I'm not going home with any of this." Plus, he promised her hostas would soon be large enough for her to come back and share divisions.

Local garden exchanges, held in the spring and fall, attract a mix of newbie and seasoned gardeners. The format resembles a tailgate party, as gardeners open their trunks or flatbed trucks to display plants, some potted, some bareroot.

At the Redmond swap, offerings included roses, bamboo, ornamental grasses, iris, daylilies (Hemerocallis), asters, ferns, scabiosa and Shasta daisies (Leucanthemum).

"If you're into gardening, this is great," said Christine Robertson of Mercer Island as she carried a bag of dahlia tubers to trade. "You can get things here you can't get at nurseries."

Many arrange advance trades through GardenWeb's Pacific Northwest plant exchange forum (see box below for details), then bring extras for impromptu trades or giveaways. "We've all got a bunch of extra stuff in our gardens, and rather than throw it in the trash pile, we'd rather give it away," Robertson said.

On her car trunk, Karee Oliver of Kirkland posted lists of her "haves" — red valerian, strawberries, dahlias, lilac, columbine (Aquilegia) and hostas — and her "wanted" — salvia, nicotiana, sedum, chocolate cosmos (Cosmos atrosanguineus), poppies (Papaver) and lavatera. She'd already scored some hostas, delphiniums and black-eyed Susan (Rudbeckia hirta) from her "wanted" list and was praising the self-seeding red valerian (Centranthus ruber) to potential takers.

"You always get things you never thought of," said Oliver. "If you don't know what something is, they'll tell you what it is and what to do with it."

That extends to unknown plants in one's own garden. "When you buy a house, plants aren't usually labeled," noted Jean Tinnea of Seattle, who came looking for "blue-flowered things" and offered wild lilac, iris and cerinthe. "Part of the fun of coming is someone can identify your mystery plants. There's always more to learn."

Some gardeners bring books or print pictures and descriptions from Web sites to show what plants (or a plain clump of roots) look like in bloom.

"Don't be afraid to show up if you don't have anything (to trade)," Oliver advised. "People are really interested in helping new gardeners. Everyone is so friendly and generous."

Stephanie Dunnewind: 206-464-2091 or sdunnewind@seattletimes.com