public void addPlantsToWorld(final Grid g) {
	Thread plantWatcher = new Thread(new Runnable() {

		@Override
		public void run() {
		    int n = 0;
		    while (true) {

			while (Grid.plants.size() < nPlantsInWorld) {
			    if (nPlantsInWorld - Grid.plants.size() >= 4) {
				n = 4;
			    } else {
				n = nPlantsInWorld - Grid.plants.size();
			    }
			    addPlants(g, n);
			}
		    }
		}
	    });
	plantWatcher.start();
    }