Growing Marijuana plant

Ok, i need help making these models working with a script that will allow it to grow and evolve through the stages and when fully developed to where the player can harvest it to use with the weed included in the drugmod link below or sell for a random amount of money between 100-1000, i would like it to be bought for 250.the command to buy it would be /buyweedplant

                                                                                            thanks,
                                                                                                        joshua_w

drugmod; http://www.garrysmod.org/downloads/?a=view&id=63955
models; http://www.garrysmod.org/downloads/?a=view&id=68156