Open Monday through Thursday, 11:30 a.m. to 4 p.m. and 5:30 to 10 p.m.; Friday and Saturday until 11:30 p.m.; Sunday, 1 to 9:30 p.m. AE, BA, CB, MC, Diners. Reservations.

Food: French, sometimes glowing but not brilliant

Style: As gracious and pretty as a garden party

Price: Everything from a $2.25 sandwich to a $25 beef Wellington

SHOPPING CENTER CONCRETE is not usually fertile soil for an indoor garden. But La Guinguette, in the Merrifield Shopping Mall, has lined its walls with cinema-size photos of flowers, hidden its regularity with white trellises. The few hanging plants make no attempt to duplicate a jungle, but one does get a sense of a well-manicured park. And few parks in the area provide such a sense of space when they are filled to capacity. La Guinguette has had the good sense to scatter its tables to break up uniformity, and allow privacy as well.

A thoughtful restaurant. With thoughtul service. Enough polish, but little pomp. Waiters in black tie display their training well, attend without hovering. And with prices at lunch starting at $2.75 for entrees or $2.25 for sandwiches, there is the potential for a real bargain in service and charm. In few other places could you lunch graciously, leisurely, formally for under $5. A $2.75 omelet, or something more extravagant like a $3.75 rockfish marseillaise or poached salmon with hollandaise, accompanied by a garlicky salad of Boston lettuce and sauteed potatoes, a glass of Almaden chablis and noticeably good bread and butter - add excellent coffee for thirty-five cents - and it is little to pay for such a pleasant place to be.

This is not the restaurant to splurge. You could spend $3.25 for oysters Rockefeller as a dinner appetizer, or share a beef Wellington at $25 for two. Most of the dinner entrees are $8 or more, and, as pleasant as the restaurant may be, the cooking is uneven, so you need to order with care.

I haven't yet discerned a pattern, the secret to choosing well at La Guinguette, but here is what I have found.Rockfish is respected here, its thick filets fresh and moist, complemented by fragrant, creamy pink nantua sauce or a lighter marseillaise with tomato and fennel. Dover sole, on the other hand, crumbles under the fork and suffers from a garnish of saline mussels and chewy shrimp. As for meats, steak Diane is a dish of dignity, two thick filets flamed tableside in a heady brandied brown sauce. Maybe there is a pattern, after all, for the flamed duck with cherry sauce is similarly distinctive, its sauce with just the right balance of sweetness and alcohol. You are on firm ground with veal, pale scallops lightly floured, cooked until lightly browned but still tender. The veal works well as a simple, unsauced francaise or in a slightly thickened marsala sauce studded with fresh mushrooms. But the suave brown sauce does not overcome the fattiness of the thinly cut lamb chops. The menu is a recital of French standbys, from coq au vin to bearnaise-sauce steak, an unchanging list which shows the kitchen to be competent if not brilliant.

Beginnings and endings are less consistent than main courses. Baked mushrooms are piled high with king crab in a wine-and-nutmeg-flavored cream sauce. Onion soup is full and rich, also sparked with wine.But pate, though handsomely constructed, is subtle bordering on bland, a pitfall the crabmeat en chemise also trips right into. Most unusual of the appetizers is pumpkin soup, an autumn-colored cream tasting more of sour cream than pumpkin but certainly pleasant. And snails are snails are snails. If you want oysters, have them on the half shell, for the Rockefeller version suffocates in a drab yellow cream sauce.

The best thing about the desserts is the whipped cream, for the chocolate mousse is achingly sweet, the cream caramel merely all right. If you like to carry on the flame theme, the cherries jubilee are heavily laced with Grand Marnier. And there is said to be a very good house cake, but I think it is only a myth, since it has evaded all my attempts to order it.

Even if it does not always succeed, the effort shows at La Guinguette. The background music is unintrusive. Vegetables are fresh and sauced with hollandaise. Flowers and candles on the tables, a modest wine list that shows care in choosing good bottles for under $10. And excellent coffee. Such touches gather a lot of points.