I have heard Doc and multiple herbalists talk about not harvesting more than 1/3 of the plant. I go slow on harvesting even that much on very young plants, but mints are pretty fast growers. You can take just the top and pinch off just above a lower set of leaves. It will make the plant bushier and produce even more! I love my spearmint plant that is now 2 years old and it went to town the second year!
With any frost that is in the forecast, I do harvest much more heavily as it can sustain damage.
5 users thanked author for this post.