Any time that you need to harvest or remove the blossoming flowers from these plants, that's a good time to prune. When it comes to evergreen herbs, which include rosemary, thyme, and sage, you only need to prune about once a year, either in early spring or fall.

Should herbs be cut back for winter?

Most importantly, trim off the dead flower heads to help keep the plants bushy. Don't trim too low down the stems (a light trim of the top leaves is enough) as the plants need time to recover before the cold weather arrives and small tender shoots engendered by fierce pruning won't take kindly to being bathed in frost.

Should herbs be cut back?

Leafy (herbaceous) herbs including cilantro, oregano, chives, sweet basil, mint, tarragon, and basil are grown for their aromatic, flavorful foliage. Without regular pruning, the plants will begin to die back after flowering. Pruning generally extends their useful lives until later in the growing season.