You can invest only for a period of five years and renew again for five years only. There is no other investment tenure available for post office recurring deposits.
Keeping a deposit locked in for a minimum period of five years is long. Make sure to keep some amount of your savings in your savings bank account for emergencies. Don’t put all your savings into post office RDs.
Make sure you do not withdraw your recurring deposit before maturity. Premature withdrawal might have a penalty.