When should perennial herbs be divided?

Question

Your site said to divide perennial herbs every two to three years. I have had an herb garden and I have always let the plants go to seed at the end of the season, but I have never dug them up and divided them. Is dividing herbs every two to three years still necessary if you let them go to seed? Should all perennial herbs be divided every two to three years? When should the dividing be done?

Answer 1

Plants, like animals, have a lifespan. Dividing helps to reset the clock on that lifespan for plants. If the clumps in your herb garden are due to reseeding, dividing is really only necessary if the clumps become too big. But, if you have noticed that herb clumps have less vigor and are dying out in the center, dividing the clumps can help to revitalize them.