Tended App is described as 'Web-based garden software that allows you to design your garden, track your activities and harvests, manage tasks with a calendar view, upload photos, view reports on your growing, and see what other gardeners are doing'. There are four alternatives to Tended App, not only websites but also apps for Windows and Mac. The best alternative is Edificius-LAND. It's not free, so if you're looking for a free alternative, you could try GrowVeg or GardenPuzzle.
With Edificius-LAND get professional results even if you’re not an expert about landscape design software. In no time you can produce detailed drawings of your garden or exterior spaces design completing them with animated video and renderings.