Hummingbird mint (Agastache) is a popular perennial plant known for its ability to attract hummingbirds. Its tall spires of tubular flowers provide nectar that hummingbirds feed on. Hummingbird mint is also sometimes called anise hyssop due to its licorice-like fragrance. This hardy plant can thrive in many conditions, including heat, drought, and poor soil. While hummingbird mint is low maintenance overall, it does require some care to keep it growing well each year. One question gardeners may have is whether you need to cut back hummingbird mint plants in the fall or leave them alone. Here is a look at the pros and cons of cutting back hummingbird mint each season.
Should You Cut Back Hummingbird Mint?
Cutting back perennials like hummingbird mint in the fall helps remove old, dead growth. It is also thought to encourage new, healthy growth the following spring. Some reasons you may want to cut back your hummingbird mint include:
Removing Old Flower Stalks
Hummingbird mint produces flowers on tall terminal spikes. Once the flowers fade in summer to fall, these flower stalks die back. Cutting off the dead stalks can help improve the plant’s appearance. It also prevents self-sowing if the plant drops seeds.
Controlling Self-Seeders
While deadheading fading flowers during the season can help, some seeds inevitably form. Cutting plants back in fall helps remove seed heads and reduce self-sowing around the garden.
Preventing Pest or Disease Buildup
Leaving old, dead growth on perennial plants over winter can allow pests and diseases to overwinter. Cutting back plants in fall removes places where problems may lurk.
Cold Protection
Cutting back perennials is thought to limit damage if temperatures dip below freezing. With less top growth, there is less area to suffer cold injury.
Encouraging New Spring Growth
Removing old foliage before winter may encourage plants to produce fresh, new growth in spring. The plant can focus energy on new bud formation rather than sustaining old shoots.
Reasons to Leave Hummingbird Mint Uncut
While there are benefits to cutting back perennials, there are also reasons you may opt to leave hummingbird mint intact for winter:
Provides Winter Interest
The bronzed seed heads left on hummingbird mint can add visual interest to winter gardens. This may be particularly welcome in northern climates where winters are long.
Protects Root System
Leaving top growth intact insulates the soil and protects the plant’s root system from extreme cold. Evergreen perennials like hummingbird mint may benefit from this extra protection.
Shelters Wildlife
Insects and other wildlife may take shelter in the dry stems and foliage of perennials left over winter. Songbirds may pick at seed heads for food.
Reduces Workload
Cutting back extensive gardens full of perennials like hummingbird mint can be a big fall chore. Leaving plants uncut reduces fall cleanup.
Avoids Potential Cold Damage
If early winter cold snaps occur after plants are cut back, new growth may be damaged. Leaving plants unpruned avoids this risk.
Tips for Cutting Back Hummingbird Mint
If you opt to cut back your hummingbird mint plants, here are some tips for best results:
– Wait until the plant has gone dormant after several hard frosts. This is typically November or December in most zones. Cutting back too early may encourage new growth susceptible to freeze damage.
– Cut plants back to about one-third their height, removing any dead or damaged growth. Make cuts just above healthy buds or leaves.
– Disinfect pruning tools between plants to avoid spreading disease. Rubbing alcohol works well for this.
– Remove all cut debris from around plants and dispose of it. Do not compost diseased trimmings.
– Water after pruning to help plants cope with loss of foliage and encourage new root growth before winter dormancy.
– Add 2-3 inches of mulch around plants after cutting back to insulate roots through winter.
– Leave any mint plants that are still flowering for pollinators to enjoy as late as possible into fall. Only cut back once blooms are spent.
Should You Cut Back Hummingbird Mint Every Year?
Unless your hummingbird mint plants show signs of disease or severe cold damage, you do not need to cut them back every fall. Here are some factors to help decide if annual cutting back is needed:
– Cut back mint that becomes overly woody or unkempt looking over time. This helps rejuvenate the plant.
– Trim mint plants damaged by pests or disease to remove problems and improve appearance.
– Cut back any perennials that outgrow their space or encroach on other plants. This helps keep them controlled.
– Pruning is needed less for young, vigorously growing mint plants. Focus on older plants that become leggy or decline in vigor over time.
– Cutting back isn’t needed during mild winters. But prune if cold damage occurs to remove dead shoots.
– Mint that self-sows readily should be cut back annually to control spread. Leave cut back off less aggressive varieties.
Conclusion
Deciding whether to cut back hummingbird mint in fall requires weighing the pros and cons. While there are benefits to fall pruning, leaving plants intact also has advantages. In most cases, cutting back every 2-3 years is sufficient to maintain healthy growth. But annual fall pruning may be preferred for aggressive self-sowing varieties or plants showing significant disease or pest damage. Assess each plant individually and choose whether a trim is needed this season.
