I usually suck at logics, and could never get passed lvl 5 in this game, now I've been very ill for 3 days, and I beated the game in 1 hour 6 minutes and 46 seconds.. Shit my head hurts >.<
To pass desert:
Once you get to the desert, get the white spore plant thing to blow you to the house. Then grow the same one to blow right next to the dam. Grow a palm tree and it damages the dam a little. The coconut will roll back down to the house. Damage the dam the same way as before a few times and it will break; the coconut will go into the new river and flow into the desert.
Now u can grow your apples, and the bird will go bring you to the top.
Using the coconut, you can drop further into the next lake