I've never tried one but there are several options online - free and not free..

http://www.gardenista.com/posts/the-top-ten-gardening-apps-you-need-now

Tended App is a free option for vegetable, fruit, and herb gardening: https://www.tendedapp.com/ It's web-based, so works on computers, tablets, and phones. It lets you visually design a garden (including across different seasons, so you could keep track for crop rotation purposes), track your inputs and outputs/harvests, and lets you see other gardeners' layouts as well. There's also basic task management on a calendar view, the ability to upload photos, etc.