When Ammar Swalim took over a small Pacific Heights hardware store two weeks ago, he knew he’d be inheriting tightly packed aisles filled with hammers and bleach and lightbulbs. He had no idea what was growing in the backyard of the California Street business: a massive avocado tree dripping with fruit so plump that each one makes a loud thump when it falls to the ground.

The avocado tree — lush, verdant and with too many branches to count — towers over the backyard with a magical presence. The fact that an avocado tree this large, estimated at nearly 50 feet tall, is bearing softball-sized, lime green avocados in foggy San Francisco adds to the mystique. They typically grow best in warm, humid climates, and it can take as long as 15 years for an avocado tree planted from seed to yield fruit.