Agastache Care: Growing Hummingbird Mint
Agastache, known by common names like Anise Hyssop or Hummingbird Mint, is a fantastic group of perennials prized for their long bloom season, aromatic foliage, drought tolerance, and incredible ability to attract hummingbirds, bees, and butterflies. Producing spikes of tubular flowers in shades of purple, blue, pink, orange, and white from mid-summer often until frost, they add vibrant color and life to sunny borders, rock gardens, and containers.
Common Types of Agastache
Many species and numerous hybrids offer different colors, sizes, and hardiness levels:
Hardier Types (Often Zones 4/5-9)
- Examples include: Agastache foeniculum (Anise Hyssop - native, lavender-blue, hardy Zone 4+), Agastache 'Blue Fortune' (popular sterile hybrid, powder-blue, Zone 5+), Agastache rugosa (Korean Mint - purple flowers, Zone 5+).
Southwestern/Less Hardy Types (Often Zones 6/7-10)
- Often more vibrant colors (orange, pink, red) and require excellent drainage, especially in winter. Can be short-lived in colder/wetter climates.
- Examples include: A. cana (Mosquito Plant), A. rupestris (Sunset Hyssop), A. mexicana, and numerous hybrids like the 'Kudos™' series, 'Poquito™' series, 'Apricot Sprite'.
Planting Agastache
Success hinges on full sun and sharp drainage.
When to Plant
- Spring: Best time, after the danger of frost has passed. Allows plants to establish well before winter. Fall planting can be risky, especially for less hardy types in cold zones.
Ideal Growing Conditions
- Light: Full sun (6-8+ hours daily) is absolutely essential. Less sun results in weak, floppy growth and poor flowering.
- Soil: CRITICAL: Light, lean, and exceptionally well-draining soil. Sandy or gravelly soils are ideal. They hate wet feet, especially winter wetness which is often fatal. Avoid heavy clay unless heavily amended for drainage or planted in raised beds.
- Spacing: Space 1.5-2 feet apart to ensure good air circulation, which helps prevent fungal issues in humid climates.
Planting Technique
Select the location with the most sun and the best drainage in your garden. Raised beds or slopes are excellent.
If your soil is heavy, amend significantly with compost and grit, gravel, or coarse sand to improve porosity. Avoid overly rich amendments.
Dig a hole about the same depth as the root ball and slightly wider.
Gently remove the plant from its pot. Place it in the hole so the top of the root ball is level with the surrounding soil surface.
Fill the hole with the amended soil, gently firming around the base. Water well once to settle the soil. Future watering should be infrequent.
Winter wetness is the biggest killer of Agastache, especially the Southwestern types. Providing sharp drainage is more important than soil fertility. Do not mulch heavily around the crown, especially over winter.
Watering Agastache
- Water regularly during the first few weeks after planting to help establish roots.
- Once established, Agastache are highly drought-tolerant. Water deeply but very infrequently, only during prolonged, severe drought.
- Allow the soil to dry out thoroughly between waterings. Overwatering leads to root rot and weak growth.
Fertilizing Agastache
- Generally not needed or recommended. Agastache thrive in lean soil.
- Fertilizing often results in excessive leafy growth, floppy stems, reduced flowering, and potentially decreased hardiness.
- If planting in extremely poor sand, a single light application of compost in spring is the most that might be considered.
Maintenance and Pruning
Pruning (Important Timing!)
- DO NOT cut back Agastache stems in the fall! The hollow stems provide some winter protection for the crown. Cutting them back allows moisture to enter and can lead to crown rot over winter.
- Wait until SPRING to prune. Cut back the dead stems once you see signs of new growth emerging at the base of the plant. Cut stems down to about 4-6 inches.
Deadheading
- Deadheading spent flower spikes during the blooming season can sometimes encourage more blooms, but it's often not necessary as they bloom profusely anyway.
- Leaving seed heads can provide food for birds like goldfinches. Note that A. foeniculum can self-seed readily.
Winter Care
- The best winter protection is excellent drainage and leaving the stems standing.
- Avoid heavy winter mulch right around the crown, which can trap moisture. A light layer of gravel or leaving fallen leaves is usually fine.
Troubleshooting Common Problems
Agastache are relatively trouble-free when grown in the right conditions.
Root/Crown Rot
Symptoms and Management
Plant base becomes mushy, stems yellow and wilt, plant collapses. The most common issue.
- Cause: Poor drainage (especially winter wetness), overwatering.
- Prevention: Provide excellent drainage! Amend soil heavily or use raised beds/containers. Water very infrequently once established. Do NOT cut back stems in fall. Avoid heavy mulch at the crown.
- Treatment: Usually fatal. Improve drainage before replanting.
Powdery Mildew / Downy Mildew
Symptoms and Management
- Fungal diseases causing white or fuzzy patches on leaves, especially in humid conditions or if overcrowded.
- Prevention/Control: Ensure full sun and good air circulation (proper spacing). Water at the base. Choose resistant varieties if mildew is a persistent problem in your area. Often cosmetic and doesn't severely harm plant health in dry climates.
Lack of Hardiness / Failure to Overwinter
Possible Causes and Solutions
- Poor Drainage: Wet winter soil is often the primary culprit, not just cold temperatures.
- Wrong Variety for Zone: Some Southwestern types are only reliably hardy to Zone 6 or 7.
- Fall Pruning: Cutting stems back in fall significantly reduces winter survival.
- Excess Fertility/Water: Lush growth spurred by fertilizer/water is less hardy.
Conclusion
Agastache are superb perennials for adding long-lasting color, fragrance, and pollinator activity to sunny, well-drained gardens. Their tolerance for heat and drought makes them ideal for low-water landscapes. Remember the keys to success: full sun, sharp drainage, lean soil, and leaving stems standing through winter. Choose varieties appropriate for your climate, and enjoy the buzz of activity these plants bring to your garden.
