In mid-September, the leaves are changing, fall flowers — like mums — are blooming, and you’re probably wondering what plants you should prune. Wonder no more.

What Plants to Prune in September

The different seasons come with different garden tasks. Some times of year are better for planting, others for pruning. Fall is typically better for planting since the weather is more moderate and the ground is still warm. Pruning certain plants this time of year can negatively impact its health and vitality. Not to mention, you may end up cutting off spring blooms. However, there are some plants that can get pruned now:

• Perennial herbs. Lightly prune rosemary, oregano, and thyme to help keep them compact as they enter dormancy.
• Shrub roses. Deadhead spend blooms and help encourage airflow for healthy flowers next year.
• Summer-flowering shrubs. Remove any faded flowers.
• Lavender. Cut back to the woody stems to encourage thicker regrowth.
• Tree hazards. It’s always a good idea to remove dead, diseased, and damaged branches to prevent breaking and causing damage.

Just as there are plants to prune this time of year, there are some you should leave alone.

What Not to Prune Now

Fall is not an ideal time for pruning. Making cuts encourages new growth, which could potentially be too weak and vulnerable to survive harsh winter weather. You also don’t want to prune any spring-flowering plants — like rhododendrons, azaleas, and magnolias — as they’ve already begun to grow buds so you’ll be reducing next year’s beautiful blooms. Typically, if the plant blooms in the spring, wait until next year to prune, after the flowers fade. Any major pruning to reshape a tree or shrub should wait until the plant is dormant during the winter.