Green Monday falls on the second Monday of December, which is December 14 in 2020. While it's not as big as Cyber Monday, this is still the last big shopping event before Christmas. And because many stores' holiday shipping deadlines fall in mid-December, Green Monday could be your last chance to put an order in before the holiday rush kicks in. That's why we're rounding up all the shopping advice you need, as well as the best Green Monday deals for 2020.