Trying to spawn random falling rocks, can't figure out why it's not working. Help would be appreciated!

I am making a 2D adventure game. In one level, the player is faced with a chamber full of rocks that are falling from above screen height and down to the ground the player is on, and kills the player if one hits him.

The problem I am having is the delay between rock spawns. I tried an IEnumerator function called after every rock spawn, but it doesn't seem to work. Unity just freezes when I run the code.

Here is my full code:

 using UnityEngine;
 using System.Collections;
 
 public class SpawnRocks : MonoBehaviour {
 
     public static Transform rockSpawn;
     public GameObject[] rocks;
 
     int spawnSpot;
 
     void Start () {
         SpawnRock();
     }
     
     void Update () {
 
     }
 
     void SpawnRock() {
         //change up spawn position of rocks a bit
         spawnSpot = Random.Range(-1, 8);
         //pick a random rock prefab from our array of prefabs, copy it to the new theRock object
         GameObject theRock = rocks[Random.Range(0, rocks.Length)];
 
         //spawn theRock
         Instantiate(theRock, new Vector3(transform.position.x + spawnSpot, transform.position.y, transform.position.z), Quaternion.identity);
         //give it a random direction and velocity
         theRock.GetComponent<Rigidbody2D>().velocity = ((Vector2)Random.onUnitSphere).normalized * Random.Range(5, 10);
 
         //destroy theRock after 2 seconds
         Destroy(theRock, 2f);
 
         //wait for a random amount of seconds
         Wait();
 
         //spawn another rock
         SpawnRock();
     }
 
     public static IEnumerator Wait() {
          yield return new WaitForSeconds(Random.Range(.2f,.5f));
     }
 }

If I delete the recursive SpawnRock(); call at the bottom, and take out SpawnRock(); from the Start function, then add it to just Update(), rocks just continually spawn until the game lags out. I know it must be something wrong with my Wait function, but I cannot find out what.

Any help is much appreciated! Thank you in advance.