We'll give it to you straight: A money tree only ever bears money once, after which it just becomes a standard hardwood tree. However, there is a way to get way more than 3,000 bells from a money tree so you can really make each one count. 

Though the bag you find when you dig at the site where the ground glows only contains 1,000 bells, you don't necessarily have to rebury that bag to plant your money tree sapling. You can instead go into your pockets and grab 10,000 bells from your purse. This will put a bag with that amount in your pocket, which you can bury in place of the 1,000-bell bag.