In the simple act of sharing tea, Joel Fath reveals himself to be an unusual person in habit and profession. He has big ideas, too, involving something small - seeds.

He wants to collect, preserve, and share them.

First, tea.

Ever considerate of the hardwood floors, we're sipping and shoeless in his sunny apartment, 11 stories up on Pine Street in West Philly. The view is predictably stupendous.

Inside is not quite what you'd expect: There's no TV in here, and no Internet connection. For heaven's sake, the guy is 31! He's even got books - real ones, with paper pages - to return to an actual public library later in the day.

We drink raspberry tea, not Fath's own mix, although he does make tea from native chokeberries. We sweeten that lovely zing with local honey and savor crunchy slices of bread from an artisanal bakery in Lancaster.

Speaking of local, which Fath does a lot, he and his wife, Ashley Opalka, an admission associate at the Philadelphia School, made the purple-red jam we're spreading from wild serviceberries harvested in West Philadelphia.

Now, in a roundabout way, it makes sense that Fath, with two others, would be heavily involved in the Philadelphia Seed Exchange (phillyseedexchange.org), which has been perking along for two years now. All serious gardeners with full-time jobs, they volunteer their nights and weekends to run this unusual enterprise, which offers local, naturally pollinated, heirloom vegetable seeds, and some flowers, to other gardeners for free.

There's Fath, whose family on both sides has been farming for at least three generations, who farms and cooks at Pendle Hill, a Quaker retreat and conference center in Wallingford. He also gardens on the second-floor roof of a parking garage next to his apartment building.

Mira Sophia Adornetto, 34, is the director of technical support at the University of the Arts. A California native now living in South Philly, she's especially interested in growing plants that make good natural dyes.

Aimee Hill, 33, is a high school science teacher from the Far Northeast who's done everything from running a seed bank in San Francisco to raising oysters sustainably in Alaska. She lives in South Philly now and gardens on a vacant lot in North Philly.

The exchange got started with 10 pounds of seed donated by the venerable Seed Savers Exchange in Iowa (seedsavers.org), but anyone can donate. (Eventually, Fath hopes to open neighborhood seed banks in the city, expand into South Jersey, and enlist garden centers to collect seed donations from the public.)

Fath, Adornetto, and Hill store the seeds in jars and envelopes in their homes. They also run seed-saving workshops, as well as seed and plant swaps at garden events and "green" festivals where, in exchange for free seeds, gardeners are asked to join the exchange - and commit to bringing back new seeds next year, to replenish supplies.

Which is likely to be the biggest challenge the group will face, according to Ken Greene, who established the Hudson Valley Seed Library in New York in 2004.

"Whether you're a seed bank, library, or exchange, there's always a lot of interest and enthusiasm," he says, "but when it comes down to actually getting people to save seeds and bring them back, that's the hardest thing to do."

That's because even experienced gardeners don't know how to save seeds and, Greene says, "we've all been raised to be throwaway consumers. We buy something, it's done, we get rid of it and buy something new."

These days, though, Greene can hardly keep up with requests at his seedlibrary.org. He describes the growth in such seed-related enterprises over the last two years as "an explosion across the country," mostly in California, where activism against genetically modified food is intense.

More and more, suggests Cheryl Moore-Gough, coauthor with her late husband Robert Gough of The Complete Guide to Saving Seeds (Storey, 2011), "people don't want to be dependent on big corporations to supply their food. For many reasons, they want to grow their own."

Collecting your own seeds is cheaper. It guarantees a plant's suitability to the local climate and soil conditions. And it's one small way for a gardener to fight the global loss of genetic diversity.

"Don't forget," says George DeVault, owner of Pheasant Hill Farm outside Emmaus and a former executive director of the Seed Savers Exchange in Iowa, "150 years ago, there were 8,000 different apple varieties in this country. Now, you're lucky to find 10 to 15 percent of that."

With that loss comes a certain insecurity in our food supply. "Plus, we're missing out on a lot of good food and good taste," DeVault says.

For Fath, the idea of saving and sharing seeds was an outgrowth of his work on farms in Indiana, Michigan, and Pennsylvania. The year he spent working with labor unions in Asia, photographing conditions in giant garment and electronics factories, also played a part.

"My generation, born in the '80s, we're just consumers. We don't know where those goods on the shelf come from. It's the same with food," he says, describing the seed-saving movement as "a positive take on an international problem."

It's a take Greene applauds.

"Our seed library started the same way - small - but what the Philly Seed Exchange is doing is wonderful and important.

"Remember," he says, "seeds are tiny, but seeds are powerful."

How to go about saving seeds

If you're interested in saving seeds, start with the easiest ones - herbs like cilantro and dill, which are quick to bolt.

That simply means that when the weather gets hot, they change gears. As a matter of survival, their energy switches from growing leaves to producing flowers and seeds for the next generation.

Let the plants get nice and dry, then pull the seeds off the stalks, put in an envelope or tight jar, and store till next season in an "evenly cool place," away from sunlight, says Nancy Wygant, an assistant gardener at Bartram's Garden in Philadelphia and an experienced seed-collector.

Lettuce is another easy one.

Let a few plants bolt, which you'll know is happening because you'll see little fluffy white seed heads. Bend the whole top of the plant into a paper bag, and shake. "You'll have more seeds than you're ever going to need," Wy-gant says.

But here's a twist: Don't take seeds from the first plant to bolt. Harvest from the last one, instead, in hopes of replicating that next year.

Peas are another good choice for seed-saving. Just let them get very dry on the vine before you pick.

In terms of shelf life, just like humans, germination rates decrease with age. Still, seeds you collect yourself will likely be more vigorous than what you buy.

Wygant suggests growing at least eight plants per variety that you want to save seeds from. If you save from only one or two per year, you're setting up what amounts to an inbred gene pool, "sort of like taking the genetics of that variety and putting it through a funnel," Wygant says.

You'll be OK for a generation or two, "but after a few more, things don't look so good anymore," she explains, citing disease, stunted growth, weird color, or other characteristics.

Wygant urges gardeners interested in collecting seeds to stay away from plants like squash, beets, and corn, which can cross-pollinate and hybridize, making it hard to keep the variety pure.

And stick with heirlooms, which are naturally (or open) pollinated and mostly non-hybrid. Seeds from hybrids, which are the result of crossbreeding, a human intervention, will not have the same characteristics as the plant you took them from.

If that's OK with you, Wygant says, have at it.

She once collected seeds from her 'Sun Gold' cherry tomatoes, a popular hybrid. The progeny were all sizes, red, orange, sugary sweet, and acidic. "I had 50 plants and no two were exactly alike. It was fun," Wygant recalls.

But breeder, beware. Once consumed, those 50 little tomatoes produced one giant bellyache.

"I now know why wine-tasters spit out the wine they taste," she says.

- Virginia A. SmithEndText

Joel Fath talks about seeds at www.philly.com/ginnyEndText

Contact Virginia A. Smith at 215-854-5720 or vsmith@phillynews.com.