GridLayout apila todos los JPanels en la primera celda

I am trying to create a map for a game I am making with a JPanel that uses gridLayout. In my first tests I use a 5x5 grid and create my small panels which are a subclass of JPanel. My program creates them fine but when I add all of the panels into the larger panel and display it, only the first square shows up and the rest is blank. Why does it do that? Here is my code for the MapSpace(smaller panel):

import javax.swing.*;
import java.awt.*;
public class MapSpace extends JPanel{
    private int ownerTag;
    private int xPos, yPos;
    public MapSpace(){
        xPos = 0;
        yPos = 0;
        ownerTag = 0;
        setBackground(Color.WHITE);
    }
public MapSpace(MapSpace m){
        xPos = m.getX();
        yPos = m.getY();
        ownerTag = m.getID();
        setBackground(m.getColor());
    }

and here is my code for the Map:

import javax.swing.*;
import java.awt.*;
import java.util.*;
public class Map extends JPanel{
    private int cols, rows;
    private int randCol, randRow;
    private MapSpace[][] spaces;
    Random gen = new Random();
    public Map(int w, int h){
        cols = h;
        rows = w;
        setLayout(new GridLayout(cols, rows));
        setBackground(Color.WHITE);
        spaces = new MapSpace[cols][rows];
        for(int i = 0; i < cols; i++){
            for(int j = 0; j < rows; j++){
                MapSpace panel = new MapSpace(i, j);
                spaces[i][j] = panel;
            }
        }
        assignSpaces(3);
        setColors();
        for(int i = 0; i < cols; i++){
            for(int j = 0; j < rows; j++){
                MapSpace spot = new MapSpace(spaces[i][j]);
                add(spot);
            }
        }
        setSize(400, 400);
    }

the second nested for loop is where all the mapSpaces are added but when I put the map in a JFrame and display it in a GUI window only one small square in the top left corner appears.