How do I know when to say a berachah on terumot and ma'aserot for redeeming ma'aser sheni?

Answer

Which fruit trees do you have? Most fruits (with the exception of lemons, loquats, and almonds) will only reach chanatah after Tu Bishevat. For them, you will say a berachah on separation plus pidyon ma'aser sheni. In the future (next year), we instruct people to harvest their ripe lemons before Tu Bishevat so it will be clear which year they belong to and avoid situations of halachic doubt. For your lemons, after this coming Rosh Hashanah, you can say a berachah on both terumot and ma'aserot and pidyon ma'aser sheni.