Western Hyssop Plant Care
Agastache occidentalis (Piper) A.Heller
Updated · Sources · How we source care data
Agastache occidentalis is a species of Agastache first described by Charles Vancouver Piper, and given its current name by Amos Arthur Heller. It is commonly known as western giant hyssop and giant horsemint.
Every 7–10 days
Full sun to partial shade
50–85°F
40–60%
At a glance
How do you care for Western Hyssop?
Water Western Hyssop every 7–10 days, letting the top layer of soil dry out between waterings, and give it full sun to partial shade. It prefers temperatures of 50–85°F (10–29°C) and 40–60% humidity. Fertilize it every 6 months during the growing season.
What Is the Western Hyssop?
Western Hyssop (Agastache occidentalis) belongs to the Lamiaceae family within the Agastache genus.
Western Hyssop displays an upright, bushy perennial growth habit, reaching up to 2 ft tall with a spread of approximately 1.5 ft. Western Hyssop produces spiky clusters of tubular flowers in shades of purple, pink, or blue.
Leaf size: approximately 4 inches.
How Often Should You Water a Western Hyssop?
Agastache occidentalis requires watering every 7–10 days. Allow the top layer of soil to dry between waterings to prevent root rot. Reduce watering frequency during winter when growth slows.
Watering Frequency
Every 7–10 days
Let soil partially dry between waterings
What Light Does the Western Hyssop Need?
Western Hyssop thrives in full sun to partial shade.
Light Requirement
Full sun to partial shade
What Temperature and Humidity Does the Western Hyssop Prefer?
Agastache occidentalis grows best at temperatures of 50–85°F. Western Hyssop prefers humidity levels of 40–60%.
Temperature
50–85°F
Humidity
40–60%
What Soil Mix Works Best for a Western Hyssop?
Well-draining sandy loam with added compost for nutrients. Good drainage is essential for Western Hyssop to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Western Hyssop?
Feed Western Hyssop every 6 months during the growing season (spring and summer) with a balanced fertilizer diluted to the strength on the label.
Pause feeding in autumn and winter, when growth slows, and never fertilize dry soil — water first.
Fertilizing
Every 6 months
During the growing season
The PlantoScan app can remind you when to water and when to fertilize each plant.
How Do You Repot a Western Hyssop?
Repot every 2-3 years in early spring. Choose a pot one size larger than the current container, and ensure it has drainage holes to allow excess water to escape.
How Do You Propagate a Western Hyssop?
Western Hyssop can be propagated through seeds, stem cuttings. Similar propagation techniques also apply to anise hyssop plant care, which shares the same genus.
Is the Western Hyssop Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Western Hyssop, so we can't confirm whether it is safe for cats and dogs. Keep pets from chewing it as a precaution.
This is a general caution, not veterinary or medical advice. If your pet ate a plant, contact your vet or animal poison control.
See all plants toxic to cats and plants toxic to dogs.
What Pests and Diseases Affect the Western Hyssop?
Western Hyssop is susceptible to aphids, spider mites, whiteflies. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.
Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.
What USDA Hardiness Zone Does the Western Hyssop Need?
Western Hyssop grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. In cooler regions, grow Western Hyssop as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 12a
Keep exploring plants
Western Hyssop is one of many species covered in the complete plant care and identification guide, which groups plants by genus, attribute, and popularity.
It belongs to the Agastache genus — compare its care with other Agastache species on PlantoScan.
Agastache is part of the Lamiaceae plant family — browse all Lamiaceae genera and species.
Western Hyssop thrives in bright light and direct sun — see other bright-light plants.
More Agastache Species
Other Agastache species in PlantoScan's care catalogue share similar watering, light, and soil preferences:
Sources
- Scientific name & taxonomy: Agastache occidentalis (Piper) A.Heller, family Lamiaceae (first published in Muhlenbergia 1: 4 (1900)) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Western Hyssop, so we can't confirm whether it is safe for cats and dogs. Checked against the ASPCA plant list; any other toxicity note on this page comes from PlantoScan's plant database.
- Hardiness zone: USDA Zone 12a, calculated from the plant's minimum temperature.
- Care values(watering, light, temperature, humidity, soil, fertilizing): PlantoScan's plant database, filtered by automatic plausibility checks — values that fail them are hidden. How we source and check plant data.
Spotted a mistake? Email info@upvision.media with the page link — we check and correct reported errors.
Identify Plants Like the
Western Hyssop Instantly
Scan any plant with your phone camera and get instant ID, care tips, water and fertilizer reminders, and health checks — all in one app.
Free
to download
iOS & Android
platforms
Light & dark
mode
100,000+
species