Without trees to generate oxygen, humans would have to retrieve it from scuba tanks and the minty breath of local supermen. Keep the air alive with today's Groupon: for $20, you get $40 worth of plants, flowers, trees, and accessories at Platt Hill Nursery, with locations in Bloomingdale and Carpentersville.

The soil and bounty purveyors at Platt Hill Nursery carry an impressive collection of trees, shrubs, flowers, and accessories. Spruce up shy flower beds with a lilac bush ($19.95+), or plant a rotation of hydrangeas ($24.95+) to restock your spring collection of dried-flower trading cards. Platt Hill offers an assortment of trees ($49.95+) as well as shrubs ($9.95+), houseplants ($5.95+), and perennials ($9.95+/gal). The professional horticulturalists at Platt Hill Nursery can help budding arborists select the ideal climate-specific tree from the selection of evergreen, shade, and ornamental trees, or help love-sick scribes decide on which genus of rose to send to their frustratingly platonic muse.