Gardening is not just about making your house look good (although a touch curb appeal certainly never hurts). Caring for plants can also do wonders for your own wellbeing, an abundance of scientific research suggests. The workout can contribute to a healthy weight and vital sign levels, and just interacting with flora can improve your mood and psychological state. “Nature has a huge impact on health and wellness,” says Gwenn Fried, manager of Horticulture Therapy at NYU Langone’s Rusk Rehabilitation. “We know that people’s cortisol levels go down during a calm, green environment.” Roll up your sleeves and get digging, planting, and weeding this spring and summer. Here’s how tending…