How to Grow Agastache
Agastache rugosa
Agastache produces spikes of purple-blue flowers from midsummer to autumn, beloved by bees and butterflies. Plant in full sun in light, well-drained soil — it hates winter wet. The anise-scented foliage is aromatic and edible. Leave seedheads standing over winter for structure, then cut back hard in spring once new growth appears at the base.
Yearly Lifecycle
Care Essentials
Minimal feeding required. A light mulch of gravel or grit in spring helps drainage around the crown. Avoid rich, heavy mulches.
Watch For
- Crown rot in wet winter soils
- Powdery mildew in dry summers
- Short-lived in heavy clay — treat as short-lived perennial
Care Requirements
Light
Full sun
Requires at least 6 hours of direct sun per day. In partial shade it becomes leggy and flowers poorly. A south- or west-facing position is ideal.
Watering
Low; drought-tolerant once established
Water in after planting and during the first season. Once established, agastache is very drought-tolerant and rarely needs additional watering. Overwatering, especially in winter, is the main killer.
Fertilizing
Minimal; avoid rich feeds
Feed sparingly, if at all. Rich feeding promotes lush but weak growth that is more susceptible to rot and less floriferous. A light top-dressing of grit or sharp sand in spring is more beneficial than fertiliser.
Pruning
Cut back hard in mid-spring
Leave all old stems standing through winter — they protect the crown and provide habitat. In mid-spring, once you can see new shoots emerging at the base, cut all stems to ground level. Do not cut back in autumn.
Overwintering
Hardy but hates wet; protect crown from waterlogging
Fully hardy in most climates but will die in waterlogged soil over winter. Improve drainage before planting. Apply a collar of grit or gravel around the crown in autumn to deflect moisture. In heavy clay, growing in a raised bed or container may be more reliable.
Growing Tips
Drainage is everything
Dies in wet winter soils; grow in very free-draining soil or raise the planting site; add grit to clay.
Leave old stems standing
Hollow stems provide winter interest and protect the crown from frost; only cut back in spring when new base growth is visible.
Edible and aromatic
Leaves have a strong anise flavour; use fresh in salads, herbal teas, and as a garnish; the flowers are also edible.
Short-lived but self-seeds
Typically lasts 3-4 years; allow some seedheads to scatter and replacement plants will appear nearby in well-drained spots.
Pests & Diseases
Pest Aphids
Pest Spider Mites
Disease Crown Rot
Disease Powdery Mildew
Popular Varieties
Morello
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