You can make a website a quick app icon in the app drawer.
Android allows you to go to Grow Diaries website and click on the options in the browser and it says "Add to Home Screen" click on that and it makes an app icon.
When I had an IPhone, they had the same option. If you're using Safari, go to the website and click Share, then it gives the same option, "Add to Home Screen"
If using Chrome, it has "Add to Home Screen" on both Android and Iphone.