Planning to make full use of Brooklyn’s many parks and gardens this spring and summer? You can give a little bit back at New York Cares Day this Saturday. New Yorkers are probably more aware than anybody of how valuable green spaces are, so no less than 5,000 of them join together every April to pitch in and spend a day cleaning and maintaining our vast array of urban oases. Register with a group of friends, coworkers or family members or join a preexisting team online and take the opportunity to meet some new Brooklynites. Either way, you get to spend the day outside contributing to one of New York’s greatest resources. The $20 registration fee defrays the cost of organizing of the event (think of it as a tax on your carbon footprint). And when you wake up on Sunday, Earth Day, you’ll feel like you did a concrete, eco-friendly deed for once.