Reducing Memory on Binary Search Tree Insertion

Question

So I have just written a solution to binary tree insertion. It seems to be effecient but takes up so much space in comparison to others. I am wondering how I can get better at reducing space complexity in my solutions for DSA. Thanks!

Here is what I wrote:

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public TreeNode insertIntoBST(TreeNode root, int val) {

        if(root == null) {
            root = new TreeNode();
            root.val = val;
            return root;
        }
        if(val > root.val){
            root.right = insertIntoBST(root.right, val);
        }
        else if (val < root.val){
            root.left = insertIntoBST(root.left, val);
        }

            return root; 
        }
   }