Theatergoing can be a picnic in San Diego's Balboa Park. Literally. Many San Diegans bring gourmet picnic baskets to this lush tropical park and munch their dinners before curtain time amid the bougainvillea, eucalyptus, and roars of lions on the edge of the famed San Diego Zoo, which abuts the Simon Edison Centre for the Performing Arts in the center of Balboa Park.
What started as an amateur theater group doing Shakespeare in a more-or-less replica of the original Globe Theatre has now evolved into a thoroughly professional three-theater complex that draws audiences from all over California. It is not unusual for Angelenos to make the half-hour plane trip south for an evening of superb San Diego theater.
The centre has become one of the most critically acclaimed theater organizations in the country, ranked by some with similar troupes in Minneapolis; Dallas; Louisville, Ky.;and even Stratford, Conn.
The Old Globe Theatre Shakespeare Festival has been a yearly event each summer for the past 33 years. This year, William Shakespeare shares the spotlight with Lanford Wilson, Joseph Kesselring, and Richard Sheridan. Six plays in repertory fill the three theaters: ''Twelfth Night,'' ''Henry IV, Part 1,'' and ''Macbeth,'' as well as ''Talley's Folly,'' ''Arsenic and Old Lace,'' and ''The Rivals.''
Besides the new Old Globe Theatre (the old one burned down a few years ago and has been replaced), there is the Cassius Carter Centre Stage and the under-the-stars Festival Stage. San Diegans have come to realize that single tickets are very hard to come by - most seats this year were sold by subscription long before the festival began on June 9. It runs through Sept. 18.
Artistic director of the Old Globe is Jack O'Brien. His recent revival here of Thornton Wilder's ''The Skin of Our Teeth'' was seen by millions of PBS viewers. And his more recent Radio City Music Hall production of ''Porgy and Bess'' enjoyed a successful early summer run in New York. He is directing both ''Twelfth Night'' and ''MacBeth'' in this summer's Old Globe Festival.
Right now he is involved in casting (and raising money for) an Old Globe revival of ''Kiss Me Kate,'' scheduled to play in San Diego Jan. 12 through Feb. 12, prior to a national tour and, perhaps, a New York opening. Among the other plays due to be produced in the 1984 winter-spring season are Simon Gray's ''Quartermaine's Terms'' and Pulitzer Prizewinner Beth Hanley's ''Crimes of the Heart.''
When I attended a recent performance of ''Twelfth Night,'' I was pleased to find a relaxed crowd awaiting the performance in the garden-partylike atmosphere surrounding the Old Globe. Although the timbered exterior of the building suggests an Elizabethan edifice, the interior is plushly comfortable - strictly 20th-century. Nobody could have asked for better acoustics or sight lines.
O'Brien's current production of ''Twelfth Night,'' despite judicious cutting, revels in its own fun-and-games authenticity. The rollicking sets and costumes join in the jollity. It is all played in the hall of a great house - according to O'Brien that is where the original production took place at the turn of the 17th century. Throughout the play there is the pungent smell of holly and pine cones, as well as the delightful vision of prancing and dancing to the sound of authentic Elizabethan music.
Shakespeare's ''Twelfth Night'' is one big party for O'Brien. He stages it as a series of comic turns with a whole set of delicious rascals and lovesick suitors having a gay old time with the words of the Bard. Amidst all the outrageous camping, there is none so outrageous as Tom Lacy in the role of Olivia's steward, Malvolio. He is as endearingly funny - and extravagant - as an Elizabethan Jackie Gleason. And he manages all of this without throwing the play out of focus for a moment.
Marsha Mason, in the difficult role of the masquerading Viola, manages to make the character lovable, believable, and utterly charming. She moves like a lithe teen-ager and plays the part with superb stage presence, despite the fact that her background is mostly in film.
When the final curtain falls on this ''Twelfth Night,'' it is like the end of a delightful party - nobody really wants to go home. Out into the Balboa Park environment pours the crowd, many people stopping at the box-office windows to see if any tickets are available for other productions during this summer's festival. ''Twelfth Night'' and ''Henry IV, Part 1'' play through Aug. 27. Tonight, Mr. O'Brien's production of ''MacBeth'' premieres. It will run through Oct. 2.
So anybody planning to be anywhere in California during the next six weeks might do well to consider a voyage down to the Old Globe Theatre Festival compound in San Diego's lush Balboa Park - a subtropical paradise for Bardophiles.