Every year when spring starts to sprung, I go out in my garden with a scrappy notepad, badly draw all the beds, buy too many seeds, forget what I wanted to plant and what I have planted and where everything is. So I made a wee app.
You can draw your garden shape from map/satellite photos, direct measurements, or by tracing over your own sketched plan. Then draw in the beds and other features. It'll work out sizes and roughly how much you can plant where. Then you can add plants to your grow list and plan out where they'll all go.
Then you can get notifications to remind you what to do when, or just check the task list in the app.
It's linked to the weather where you are, but growing times are UK specific right now.