Saves and time away
From Gardens wiki
The game saves itself every 30 seconds and when you close the page. Your garden is kept on the server, tied to this browser. Clearing the browser's data, or switching to another device, starts a new garden. Export and Import in Options let you carry a save by hand. If this browser had a copy the server turned down, because the garden was saved from another tab or device meanwhile, Options says so: Export kept copy gives you that copy as a save to keep or import, and Discard kept copy throws it away. You go on with the garden on the server either way.
Time away counts in full. When you come back, everything that was running has kept running for the whole time you were gone, and a mission's reward that was on its way home (the light delay, see Missions) has kept coming.
Your name
You start as "Gardener" and four digits. To choose your own name, open Options in the header, type it in the Name box and press Save name. A name is 2 to 20 characters: letters, numbers, spaces and - _ ' . only. No one else may have it, and you can change it 3 times an hour. The chat and Legends show your new name, on old lines too.
Online
Online in the header means the game is connected to the server live (chat, the world's count, Legends' news); Offline means it isn't just now, and the game keeps going. Click it to see your name (with a link to change it), when the server last took a save, and your garden id, which helps if you ever need to ask for support.