PALO ALTO, Calif. - At first glance, the light blue cottage on Alma Street in this Silicon Valley city may not look like a place where big ideas are born.

But in the past 15 years, this modest house has produced nearly a dozen successful tech companies. Its owner swears there's something special in the air.

"You're going to get some good ideas here," said owner Genie Laborde, who runs her own consulting business out of the house and lives a few blocks away. Over the years, her entrepreneur tenants have come to think of her as the grandmother of Silicon Valley.

Nest got its start in Laborde's garage in 2010, and four years later the smart thermostat company was acquired by Google for $3.2 billion. Several other companies, after renting either Laborde's garage or basement, have raked in capital or cashed out — successes that have lent the space something of a mythical quality among start-up founders.

"I used to walk by this office and see Nest, and now Nest is a huge, huge company," said Ben Brewster, co-founder of data leveraging start-up Monetize, which moved into Laborde's basement earlier this year. "There's good potential and possibilities."

It's not just Nest. Business intelligence start-up ­EdgeSpring rented from Laborde and went on to be acquired by Salesforce for an undisclosed amount. ­Comprehend, which makes software for biotech companies, spent two years at Laborde's and piled up $30 million from investors. And education tech start-up VersaMe, another prior Laborde tenant, recently launched its first product after raising more than $100,000 on Indiegogo.

It's as if the house, which Laborde bought in the late 1990s as an office for her own consulting business, is an undiscovered incubator. The property is shaded by a handful of redwood trees, and on warm days, techies flock to the backyard to hold meetings or take phone calls.

"We all really enjoyed the idea that it was literally a garage," said Isabel Guenette Thornton, Nest's former thermostat product manager, "because you have this wonderful mythology of start-ups in garages."

Thornton found Laborde's garage on Craigslist in 2010, when the burgeoning smart thermostat company had about five people. She said the space had a playful, whimsical atmosphere that reminded her of being in a treehouse or a clubhouse — right down to the occasional brush with nature. Birds would come in when the garage door was up.

"That was sort of charming," said Thornton, who was an intern when she found the garage, and later moved up the company's ranks. "But the squirrels were less fun. That wasn't so great."

The leaky roof was even less great. By 2011, Nest was cramming more than 20 people into the garage, and had to find a bigger space. But Nest kept the memory of Laborde's garage alive by naming a conference room in one of their later offices "No Squirrels."

Cloudastructure, an access and video surveillance start-up, moved in a few years later and tried to make the garage more high-tech. The employees installed a ­system they created to unlock the door with their smartphones, and CEO Rick Bentley set up a bitcoin mining operation on the roof. He installed a small machine that ran algorithms day and night to generate the virtual currency, put it in a doghouse to protect the machine from the rain, and occasionally sent his drone to check on it.

Since moving out of Laborde's garage, Cloudastructure joined the Highway 1 incubator in San Francisco.

In some ways Laborde, a small Southern woman with snow-white hair, 16 grandchildren and nine great-grandchildren, is an odd fixture in this quintessential Silicon Valley scene. She's not interested in investing in the start-ups under her roof because she says she knows nothing about tech. When her tenants move out, Laborde marvels at the "remarkable-looking gadgets" they leave behind. But as a writer and an artist — her paintings adorn the walls of both her home and office — Laborde says she feeds off the energy her renters bring to the space.

"Creativity is a whole vibration," she said. "All of us, I think, support each other's creativity."