perennial
Anise hyssop
Agastache foeniculum
Growing guidance
Horticultural figures below are practitioner estimates for planning, pending expert review. The botanical record further down is sourced and verifiable.
Current-climate suitability
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Future-climate resilience
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Sun
Full sun
Soil moisture
free-draining, average
Heat tolerance
Up to about 42°C
Cold tolerance
Down to about -30°C
Waterlogging tolerance
1/5
Drought tolerance
4/5
Mature size
0.7–1.2 m tall, 0.5 m spread
Seasonal interest
Summer to autumn · Lavender blue
Maintenance
low
Wildlife supported
General wildlife value 5/5 (verified species relationships are shown only where structured data exists)
How to plant it
General steps for this plant. Save a garden and these become specific to your location, soil and light.
Step 1When to plant
Plant during March to May or September to November.
Autumn planting gives roots a head start; spring planting suits cold or wet soils.
Step 2Where to put it
Choose a position in full sun for most of the day. Allow 0.5 m of room around it — mature spread is 0.5 m and mature height 0.7–1.2 m.
Light in your garden is not answered, so this is the plant's own requirement.
Step 3Preparing the ground
Dig a hole twice as wide as the root ball and no deeper, loosen the sides, and plant so the top of the root ball is level with the surrounding soil.
Soil is not answered. This plant grows in free-draining, average conditions.
Step 4Watering while it establishes
Water thoroughly at planting (5–10 litres), then only when the top few centimetres of soil are dry, through the first growing season.
Even a drought-tolerant plant (4/5 here) only becomes drought-tolerant once established.
Step 5Mulch
Spread 5–7 cm of composted bark or garden compost around the plant, keeping it clear of the stem.
Mulch cuts water loss and suppresses weeds through the first summer, when losses are most likely.
Step 6The first year
Check it after strong wind and in long dry spells. Little else is needed.
Maintenance level on the plant record is low.
Step 7What to watch for
Self-seeds freely in open soil.
Taken from the plant record and your measured climate figures, not from a general description.
Spacing: about 0.5 m apart — roughly 40 plants for every 10 m² if planted as a group.
What this guide could not use
- No location saved, so planting times are general rather than local.
- Soil moisture is not answered, so soil preparation is general advice.
- Light is not answered, so the position below is the plant's own preference.
- Whether you can water is not answered, so watering assumes hand watering.
Built by fixed rules from: Plant record for Anise hyssop (last reviewed 2026-06-01). Planting guide version gf-planting-1.0.0. Timings and volumes are practitioner estimates for planning, not a substitute for local nursery advice.
Known risks or warnings
Self-seeds freely in open soil.
Toxicity: none
Status and jurisdiction
Climate-suitable non-native in United Kingdom (Great Britain).
Register consulted: GBIF Backbone Taxonomy distributions for Great Britain
Record review status: reviewed · last reviewed 2026-06-01 · plant data version gf-plants-2026.09.18. Status claims are never inferred from climate similarity, and growing figures are estimates pending expert review.
Verified botanical record
- Accepted scientific name
- Agastache foeniculum (Pursh) Kuntze
- Family
- Lamiaceae (Lamiales)
- Rank and status
- species · accepted
- GBIF record
- Taxon 2926406
Recorded native range: Alberta, Manitoba, Northwest Territories, Ontario, Saskatchewan
Recorded as introduced in: Austria, British Columbia, Connecticut, Delaware, Germany, Kentucky, New Brunswick, New Hampshire, New York, Pennsylvania, Quebec
Ranges are exactly as recorded in the GBIF source checklists and may be incomplete for widely cultivated species.
Agastache foeniculum (syn. Agastache anethiodora (Nutt.) Britton), commonly called anise hyssop, blue giant hyssop, Fragrant giant hyssop, or the lavender giant hyssop, is a species of perennial plant in the mint family. The plant is native to much of northern North America. It is tolerant of deer and drought, and is visited by many pollinators.
Description from Wikipedia — Agastache foeniculum (CC BY-SA), shortened and unedited in substance.
Native status and geographic context
- United Kingdom: climate-suitable
- United States: native
- Australia: climate-suitable
Native status is never inferred from climate similarity. Plants restricted or invasive in a jurisdiction are excluded from recommendations there.
What to do next
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written for United Kingdom
These figures come from the demonstration dataset kept for testing and as a fallback when the measured climate service is unavailable. They are representative, not observed, and are never presented as validated live data.