This sounds more professional and specific. "Established" or "mature" is the technical way to describe "big" trees that are already a few years old. If you are asking for advice:
This helps you get recommendations for trees that will produce fruit sooner. Keep in mind that some varieties, like mulberry trees , can take up to 10 years to bear fruit if grown from seed, so buying "big" is a great shortcut. Tips for Buying Large Trees: buy big fruit trees
To turn "buy big fruit trees" into a "proper text," it helps to know your goal. Here are a few ways to rewrite it depending on what you need: This sounds more professional and specific
When buying big, ensure the root ball is healthy. Home Depot recommends digging a hole twice as wide as the root ball for proper planting. Keep in mind that some varieties, like mulberry
The best time to buy and plant is typically early spring ( February to May ) to give the roots time to settle before winter.
Make sure the "big tree" you choose is native or suited to your specific area to avoid it dying shortly after a costly purchase.