Many freebies can be found in Balboa Park, both on a weekly basis and at special times of the year. Free Ranger Tours depart from the visitor center Tuesday and Sunday at 11 am providing an overview of the history, architecture, and horticulture of the park. On Saturday at 10 am, volunteers offer a rotating selection of thematic Offshoot Tours, also free of charge and departing from the visitor center. If you prefer to explore on your own, head to the visitor center to pick up a free garden tour map.
The free concerts at the Spreckels Organ Pavilion take place Sunday afternoons at 2 pm year-round and on Monday evenings in summer. Also at the Speckels Organ Pavilion, the Twilight in the Park Summer Concert Series offers various performances Tuesday, Wednesday, and Thursday from 6:15 to 7:15.
The Timken Museum of Art is always free (a donation is suggested), as is admission to the House of Pacific Relations International Cottages, although the latter are only open on Sunday. You can explore the studios at the Spanish Village Art Center at no charge, although you just might be tempted to purchase a unique souvenir.
A fantastic deal for residents of San Diego County and active-duty military and their families is Free Tuesdays in the Park, a rotating schedule of free admission to most of Balboa Park's museums.
The San Diego Zoo is free for kids under 12 the whole month of October.
The December Nights festival on the first Friday and Saturday of that month includes free admission (and later hours) to most of the Balboa Park museums. The outdoor events during the festival make it something not to miss.