SAN LUIS OBISPO COUNTY - Reiner Ng scooped his hands deeply into the layer of compost, disturbing an entire civilization of earthworms. There were dozens of them, wriggling and glistening in the sudden light. The wooden bin that held them was massive, meaning thousands more writhed beneath the surface.

The worm farm is maintained by Ng and two other families that operate the Mount Olive Co., a certified-organic farm just west of Paso Robles. The waste products of these worms revitalize the soil in the vegetable beds and orchards, a natural alternative to chemical fertilizers and insecticides. The contents of the bin are also used to make a "worm tea," which is sprayed over everything under cultivation.

Visitors are welcomed at this farm, giving city-dwellers a chance to learn about the food that ends up on their table. Ng and wife Karen conduct tours, and might usher you into the dark, humid inner sanctum of the "sprout house," where tender shoots of many varieties - pea, alfalfa, sunflower, clover, buckwheat, broccoli - tower to six or seven inches in a quest for light.

At a time when the small family farm is on the endangered list nationally,

several of these operations along the Central Coast supplement their income by opening to the public. The tours are free, but the hope is that visitors will purchase some of the farm's bounty in an on-site retail store, or perhaps seek it out at one of several farmers markets in the region.

The prime season for fresh fruits and vegetables is June through October, but even in March the Mount Olive Co.'s store had fresh garlic cloves, shallots, pumpkins and just-gathered eggs. Its tasting room offered dozens of prepared items for sampling: olive oils, stuffed olives, tapenades, salad dressings, dried tomatoes, jams, teriyaki sauce, herb teas. All are made in an adjoining kitchen, using ingredients grown on the premises - with the considerable assistance of those worms.

Other Central Coast farms that also welcome visitors include Avila Valley Barn, Blue Sky Gardens, Hollyhock Farms, Jack Creek Farms, Windmill Farms and Windrose Farms.

Meanwhile, the orchards of See Canyon - which winds between Avila Beach and San Luis Obispo - serve up a stunning variety of apples in the fall. Olive oil is a specialty of Willow Creek Olive Ranch near Paso Robles. And if you're not keen on a farm visit but still want to sample the abundant produce of the region, head to the San Luis Obispo Farmers Market on Thursday nights downtown - its one of the best in the state.

APPLE SEASON:
The apples are set out in baskets, and the interior of the weathered shed is rich with their scents. But on closer inspection, it's evident that the wares on display have no resemblance to the apples you customarily find in your neighborhood supermarket.

Here at Gopher Glen Apple Farm, tucked away in See Canyon, are Spitzenburg apples - said to have been a favorite of Thomas Jefferson. Also Staymen, Nittany, Chesapeake and Limbertwig.

Just down a winding country road, at See Canyon Fruit Ranch, are pearmain, Winesap, Missouri pippin and splendor - the latter described as a Tasmanian pink apple.

The unfamiliar varieties might be perplexing, but not to worry: Just about everything has been sliced up for tasting samples - as many as 15 different varieties on the day we visited last October. The peak season runs roughly from September to mid-November, but some farms open earlier in the summer.

See Canyon is well-suited for growing this fruit. Lying just southwest of San Luis Obispo, it's a narrow, twisting cleft that rises from Avila Beach to the crest of the Irish Hills. In winter, it'll get cold enough in the canyon for frost, yet summer can bring plenty of warm sunshine. The coastal rain and drippy fog is generally so abundant that some of the orchards are dry-farmed, rather than irrigated.

The apples flourish here, and have for quite some time. See Canyon Fruit Ranch has been in operation for more than 100 years, while the orchards of Kelsey See Canyon Vineyards were planted in 1951.

The farmers of See Canyon are so fond of their apples that the fruit tends to find its way into everything. Even wine. Dick and Dolores Kelsey pour 11 of their wines in their tasting room, including - brace yourself - an apple-chardonnay blend and an apple-merlot blend.

We found Kelsey's red-stained alchemist, Harold Osborne, in the wine barn out back. He is an avowed iconoclast, and even makes a sparkling wine from syrah grapes. (We're going to open our bottle as soon as we can figure out what it could possibly go with.) Osborne is lobbying for See Canyon to maintain its diverse agricultural heritage.

"I worked in Napa in the '70s," he said, "and there were walnuts, pears, prunes. Now it's a monoculture. Every corner of Napa is planted (in wine grapes), and Sonoma is getting that way. All of See Canyon will be grapes someday. I see myself as Melvin Appleseed; I'm trying to save the apples."

OLIVE SQUEEZINGS:
Much like a winery tasting room, Willow Creek Olive Ranch near Paso Robles lines up its bottles in a precise row along the counter. But here, visitors dip crusts of bread into dishes of the richly flavored oils to taste them.

Be sure to try Pasolivo, the farm's signature product. It's a blend of five Italian varietals grown here - frantoio, leccino, lucca, moraiolo and pendolino - and is divine for drizzling over pasta, fresh tomatoes or goat cheese.

Other oils set out for tasting recently were California Blend (a mix of mission and manzanillo olives) and four other oils infused with lemon, orange, tangerine and lime.

Proprietor Joeli Yaguda will cheerfully show visitors the new press, or suggest any number of ways to enjoy the farm's products. On weekends, from-the-box brownies might be set out - made with the orange-infused olive oil as a healthier substitute for vegetable oil. Or you might find Pasolivo poured over a hunk of sheep's cheese from Rinconada Dairy in nearby Santa Margarita.

TO MARKET:
Just before 6 o'clock each Thursday evening, a dramatic transformation occurs along several blocks of Higuera Street in downtown San Luis Obispo. Drivers of dusty pickup trucks pull in perpendicular to the curb, drop their tailgates, set up folding tables and lay out their wares: fruits and vegetables in an extraordinary array, most picked just that afternoon.

Many of the growers operate on a small scale and can't afford to commit to the urban farmers markets of Los Angeles or the Bay Area. They tend to be personable to a fault, not only selling you an artichoke, but telling you precisely how to cook it.

The downtown street is transformed to a pedestrian thoroughfare, and in addition to wondrous produce, the market is renowned for its Santa Maria barbecue offerings served from open grills, its activist information booths, and side-street entertainment that runs from the gamut from garage bands to puppet shows.

Note: Many of the farms try to keep regular visitor hours, but because they are family operations, it's a good idea to call or check Web sites before a visit. For other agricultural tourism opportunities in San Luis Obispo County visit www.agadventures.org.

IF YOU GO
AVILA VALLEY BARN:	560 Avila Beach Drive, San Luis Obispo. (805) 595-2816.
BLUE SKY GARDENS:	19505 Walnut Ave., Atascadero. www.blueskygardens.sanityonline.com; (805) 438-5801. You-pick blackberry bramble in June, summer vegetables from June through October. Open daily from 6 a.m. to 7 p.m. in season.
GOPHER GLEN APPLE FARM:	2899 See Canyon Road, San Luis Obispo. www.gopherglen.com; (805) 595-2646. Plans to open this year the last week in July.
HOLLYHOCK FARMS:	200 Hollyhock Lane, Templeton. www.hollyhock-farm.com; (805) 239-4713. You-pick garden, farm-stay cottage, honor roadside produce stand.
JACK CREEK FARMS:	4665 Jack Creek Road, Templeton. www.jackcreekfarms.com; (805) 238-3799. You-pick garden. Hopes to open in late May. Will be open Saturday and Sunday from 10 a.m. to 6 p.m. during the summer, daily in October.
KELSEY SEE CANYON VINEYARDS:	1947 See Canyon Road, San Luis Obispo. www.kelseywine.com; (805) 595-9700. Winery tasting room usually open daily from 11 a.m. to 5 p.m.
MOUNT OLIVE CO.:	3445 Adelaida Road, Paso Robles. www.mtoliveco.com; (805) 237-0147. Open Thursday through Sunday from 10 a.m. to 5 p.m. (until 7 p.m. in summer).
SAN LUIS OBISPO FARMERS MARKET:	Held every Thursday evening on Higuera Street between Osos and Nipomo streets. (The event is moved to Friday evening on Thanksgiving weekend and is canceled in the event of rain.) Barbecues and entertainment begin at 6 p.m., produce sales at 6:30. All activities conclude at 9 p.m. www.downtownslo.com/farmers.html; (805) 541-0286.
SEE CANYON FRUIT RANCH:	2345 See Canyon Road. (805) 595-2376. Open Sept. 1 to Nov. 25.
WILLOW CREEK OLIVE RANCH:	8530 Vineyard Drive, Paso Robles. www.pasolivo.com; (805) 227-0186. Tasting room open Friday through Sunday from 11 a.m. to 5 p.m. (other times by appointment).
WINDMILL FARMS:	1275 N. Thompson Ave., Arroyo Grande. www.windmillfarms.org; (805) 489-1000.
WINDROSE FARMS:	5750 El Pharo Drive, Paso Robles. www.windrosefarm.org; (805) 239-3757. Opens periodically for specially offered events.

EXTRAS
INTERACTIVE:	Apple Orchid & Vineyard