You can grow your bitcoin in many ways. I recommend you to invest in good projects and hold them for 5 years and you can see the returns after the end of the period. You can also trade when you see an opportunity coming up, but you will have to develop your trading skills. Other way is to hold on to your bitcoin and let them appreciate in their value as time pass by.
Five years? How can we be sure that Bitcoin will be worth 5 years, a very long time, and 5 years later? The most logical way to grow the Bitcoins in your hand right now is to trade. There are many stock exchange sites.