Without hesitation, 3-year-old Andrew Dries donned gardening gloves and dug into the dark soil filled with moistened bedding and fruit and vegetable scraps. He was searching for Eisenia foetida, otherwise known as the red wriggler.

As dozens of people milled about the education center at Crissy Field on Saturday for an Earth Day event, young Andrew stayed focused on his handful of red worms.

"I'll put them back now so they can be with their family," he said to the delight of onlookers.

Celebrations around the 39th annual Earth Day, which officially falls on Wednesday, began this week across the Bay Area. There was tree planting and park restoration, green home building and companies touting their environmental friendliness.

The Crissy Field Center in the Presidio, run by the Golden Gate National Parks Conservancy, held an all-day Earth Stroll Saturday, where families received an "eco-passport" to be stamped at each environmental display or project. In addition to worm composting bins, there was yoga for kids and the sorting of seeds, there were quizzes on what can and can't be recycled, and there was hands-on interaction with reptiles and amphibians.

"My daughter is very aware of the environment," said Sam Rodriguez, speaking of his 4-year-old daughter Kira. "The Presidio has always been a part of her life. It's an outdoor laboratory."

He said Kira is savvy about recycling and often scolds people who litter, telling them: "That's a bad decision."

Rodriquez said that celebrating Earth Day "reinforces values about caring and kindness."

For most families attending the Crissy Field Center event, talk was not about a planet in peril, air or water pollution, or global warming. Instead, it was about showing appreciation for a spectacularly clear, beautiful and warm Saturday in April. And it was about understanding the importance of nurturing one's environment, whether through learning how to make a "zero-waste lunch" for your kids or using cleaning products that don't harm the bay.

"This is the best type of education in that it's fun," said Nancy Ream, attending the Crissy Field event with her son-in-law Kevin Candland and her two granddaughters, Emma, 8, and Fiona, 5. The girls had stopped in at the Tree Frog Treks room inside the center, and were mesmerized watching a small female Bearded Dragon devour plump mealworms.

"It's bug month at my school and I'm studying insects and spiders," volunteered Fiona. Older sister Emma proudly noted that the family recycles, especially all of the paper clippings.

Mark Yang, attending the event with his wife Mimi Chen and their 7-year-old daughter Megan, said they recently planted a garden in their back yard, and bought three chickens.

Chen laughed saying, "My daughter's generation is growing up with this. My husband and I are just learning it. It's great."

Across town, another Earth Day event was held at Ghirardelli Square.

Where the focus of the Crissy Center event was mostly about involving kids in the environment, the Ghirardelli gathering spotlighted what local companies are doing to make the planet a better place. There was a company called GreenZebra, which offers city guides on sustainable living, a nonprofit called Scrap, billed as a "scroungers' center for reusable art parts," a landscaping company with a detailed environmental strategy, and a produce company that delivers organic produce to your doorstep.

"A lot of landscaping companies are moving toward sustainability," said Jacob Voit, sustainability manager of Cagwin & Dorward, which does the landscaping for Ghirardelli Square. "We do commercial, we do residential, and right now we are doing a lot of water management," he said, noting that there are now "smart controllers which deliver water according to the weather."

Voit said the company, with 400 employees, has reduced overall energy use by 26 percent and is working to buy and plant trees at a rate that will offset the company's carbon output.

Lindsay Maxon, marketing director for Ghirardelli Square, said the event also kicked off its new public recycling program.

"Our tenants are environmentally conscious," Maxon said, mentioning the store that buys its wine from vineyards using solar panels, the cupcake shop that uses only local ingredients, and the restaurant offering sustainably harvested fish.

"We're all very green," she said.

Earth Day events: Bay Area activities include walking tours, arts and crafts, cruises, and park and shoreline cleanups. B6

Earth Day events in the Bay Area TodayAlbanyWhat: Albany Earth Day Celebration and Cleanup. Shoreline cleanup, arts and crafts. Where: Buchanan and Pierce streets, Albany Beach When: 10 a.m.-1 p.m. Contact: (510) 665-3689, martha@thewatershedproject.org Santa RosaWhat: Earth Day Celebration at DeLoach Vineyards. Walking tours of biodynamic vineyard and garden, displays of sustainable fashions created from recycled wine packaging; spring-cleaning wine sale. Where: 1791 Olivet Road When: 11 a.m.-2 p.m. Contact: (707) 526-9111, deloachvineyards.com San FranciscoWhat:Battle for Earth Begins With Laughter. An evening of stand-up comedy that benefits the planet. Where: S.F. Comedy College clubhouse, 414 Mason St., 5th Floor When: 6-8 p.m. Contact: $10 tickets at brownpapertickets.com/event/60612 TuesdayBerkeleyWhat: Earth Day Eve Celebration. Artist Zach Pine hosts a free, create-with-nature celebration. Where: 2134 Martin Luther King Jr. Way When: 5-6:45 p.m. Contact: naturesculpture .com WednesdayOrindaWhat: Orinda Creek Restoration Day. Replace nonnative plants with native species. Where: Del Rey Elementary, 25 El Camino Moraga When: 10 a.m.-1 p.m. Contact: missrootes@ yahoo.com San FranciscoWhat: Earth Day Cruise. Cruise San Francisco Bay on the wind- and solar-powered Hornblower Hybrid. Tickets $10. Where: Pier 33 When: 11 a.m.-4 p.m. Contact: (415) 981-7625, alcatrazcruises.com San CarlosWhat:San Car-less Day and Highlands Park Celebration. Families will walk to and from school. Park celebration features kite-flying and nature. Where:2600 Melendy Drive When:1 -3 p.m. Contact: San Carlos School District, (650) 508-7333