This Saturday, the South Seattle Artisan Wineries (Cadence, Fall Line, :Nota Bene and O• S) will "Celebrate Spring" with a four-winery open house from 1 to 5 p.m. They are all relatively small boutiques, family-owned and -operated, and they craft (mostly) red wines of exceptional character and diversity.

Though only occasionally open to the public, they all have new releases this spring and are throwing open the doors to show them off. Three of the four are in South Park, just steps apart; the fourth is in Georgetown.

Cadence, founded in 1998, belongs to the husband/wife team of Ben Smith and Gaye McNutt. In 2004, they planted the Cara Mia vineyard, 10 acres on Red Mountain, near Hightower Cellars in Benton County. Cadence specializes in Bordeaux blends made from Red Mountain grapes. Single-vineyard wines from Klipsun, Ciel du Cheval and Tapteil have historically been standouts, but with the estate vineyard now bearing, the winery is focusing exclusively on grapes from Cara Mia, Tapteil and Ciel du Cheval.

This weekend, Cadence will introduce the 2006 Coda ($25). It's a particularly special occasion, as this version of Coda is the first to include grapes from their own vineyard. The blend includes petit verdot, cabernet sauvignon, cabernet franc and merlot. Coda is always the first wine of any given vintage to be released. This one is especially good, bursting with mixed fruits, polished, spicy and detailed.

A few doors down the way you will find :Nota Bene Cellars, begun in 2001 by the wife/husband team of Carol Bryant and Tim Narby. Like Ben Smith, Narby is an alum of the Boeing Employees Wine and Beermaking Club, where he was in charge of grape procurement.

Last month, :Nota Bene released a full slate of wines from the 2005 vintage. These are consistently excellent, sourced from Columbia Valley vineyards such as Stillwater Creek, Stone Tree, Conner Lee and Ciel du Cheval. The blends are various combinations of Bordeaux grapes; there is also a fine 2005 Syrah ($30) that includes a generous portion of grenache.

It's a tangy, juicy wine, packed with raspberry fruit flavors; high acid; and streaks of spice, cranberry, plum and light pepper. Moving on to :Nota Bene's single-vineyard wines, the 2005 Conner Lee Vineyard Red Wine ($32) is 57 percent merlot and 43 percent cabernet sauvignon. It stops just short of voluptuous but is beautifully scented with rose petals, violets, chocolate and graphite, and loaded with cranberry and raspberry fruit.

Its companion, the 2005 Ciel du Cheval Vineyard Red Wine ($35) adds cabernet franc to the mix. Black cherry and cassis fruit flavors are cut with vivid streaks of herb, coffee and rock. It's young and compact, a wine to savor and cellar.

The last of the three South Park wineries is O• S, formerly Owen Sullivan. It was founded in 1997 by Bill Owen and Rob Sullivan, who left wine-selling and banking careers respectively to combine forces. O• S has won high praise from many in the press (the Wine Spectator's Harvey Steiman in particular) for its very ripe and quite heady red wines, especially the Ulysses blend.

A favorite of mine is the O• S Champoux Vineyard Riesling ($22), a spicy little jewel that's loaded with citrus, light tropical and grapefruit rind. At just under 10 percent alcohol, it's a not-too-sweet wine that you can sip forever. Special for this weekend will be the release of the O• S 2006 Red Wine ($20). Chocolaty, rich and loaded with ripe fruit and smooth caramel/coffee flavors, it's the best buy on the table.

The newest addition to the South Seattle Artisan wineries group is Fall Line, whose first vintage was 2004. Tim Sorenson, an economics professor, and Nancy Rivenburgh, a communications professor, are the husband/wife owners. Completing the circle, Sorenson cut his winemaking teeth while serving as the unofficial cellar hand at Cadence winery some years ago.

Fall Line purchases grapes from vineyards on Red Mountain, the Horse Heaven Hills in the Columbia River Valley and the Yakima Valley. Three Bordeaux-style blends are made. One showcases Red Mountain fruit, one Horse Heaven Hills; and the third blend is pure cabernet sauvignon from a mix of vineyards.

All three wines (from the 2005 vintage) will be poured on Saturday, along with barrel samples of Fall Line's 2006 wines. Best of show is the 2005 Columbia Valley Cabernet Sauvignon ($30), bursting with plump cherry, berry, plum and cassis fruit.

For specifics, and a useful map showing winery locations, visit www.ssaw.info/, then select "Links to Wineries" and "Download Map."

You may also call the wineries individually to confirm exactly what will be offered. There may also be a small tasting charge, refundable with the purchase of any wines. And don't miss the music at :Nota Bene!

Fall Line Winery, 6122 Sixth Ave. S., 206-768-9463

O• S Winery, 1501 S. 92nd Place, Suite B, 206-243-3427

:Nota Bene Cellars, 9320 15th Ave. S., Unit CC, 206-459-3185

Cadence Winery, 9320 15th Ave. S., Unit CF, 206-381-9507

Paul Gregutt is the author of "Washington Wines and Wineries: The Essential Guide." His column appears weekly in the Wine section. He can be reached by e-mail at wine@seattletimes.com