Instantiating prefab in a grid help

Hello, I've been having an issue with this bit of code I wrote. It generates the prefabs onto a grid-like pattern, but it stops once it has generated a certain amount, and I cannot get it to generate any more or less. Here is the code:

 using UnityEngine;
 using System.Collections;
 
 public class GroundGenerator : MonoBehaviour {
 
     public GameObject[] grass;
 
     public float width;
     public float length;
 
     void Start () {
         StartCoroutine (Generate ());
     }
 
     public IEnumerator Generate () {
         for (int x = 0; x <= width; x++) {
             for (int z = 0; z <= length; z++) {
                 Vector3 newLoc = new Vector3 (width * x + 1, 0.0f, length * z + 1);
                 Instantiate (grass[UnityEngine.Random.Range(0,3)], newLoc, Quaternion.identity);
 
                 yield return null;
             }
         }
     }
 }

The grass prefab is 3.2 lengths long in the X and Z plane, so I have my width and length set to 3.2. Thanks for the help!