Some of the kindest people you’ll ever meet have dirt under their fingernails. Gardeners hand out tomatoes, cuttings and advice like it costs nothing — and science suggests this hobby gives plenty back. In a University of Essex study of 269 people, a single session in an allotment garden measurably lifted gardeners’ self-esteem and mood, and regular gardeners had better self-esteem, mood and general health than people who didn’t garden. From a widow who leased her late husband’s vegetable garden for $1 a year to a backyard corn maze planted for the whole neighborhood, these stories show how one small act of kindness in a garden can grow into a whole season of happiness.

Plant one act of kindness in a garden and it behaves like a perennial: it keeps coming back, season after season, a little bigger every year. Science suggests even the smallest planting matters. In one Royal Horticultural Society study, researchers gave residents of a bare, gray street plants for their front gardens. A year later, the share of people with healthy stress-hormone patterns had jumped from 24% to 53%. A $1 backyard handed to strangers, a heart of daffodils planted for a crossing guard, a neighborhood feud settled over sunflower: these stories show this hobby grows far more than flowers. It grows kindness, and the happiness that comes with it.