Old ginger refers to ginger that has been growing for a long time, commonly known as "ginger mother". It has thick skin, firm flesh and a strong spicy flavor. New ginger, also called young ginger, is the sprout of old ginger with short growth period, thin skin, tender flesh and light spiciness.
There is a saying "Ginger is still spicier when it's old", which means that in work and life, it is often the older people who can solve problems quickly, with more experience, agility and better performance. That is to say, a person has matured and gained rich experience, which is just the opposite of the meaning of the saying "not reliable if handled by a beardless youth (inexperienced)".
The phrase "Ginger is still spicier when it's old" is usually said when someone leaves a good impression or receives positive feedback after an event.