Photo: Jacek PietruszewskiCC BY 4.0via iNaturalistresized / cropped
Giant Lousewort Plant Care
Pedicularis wilhelmsiana Fisch. ex M.Bieb.
Updated · Sources · How we source care data
This unique plant is easily recognizable by its vibrant purple flowers that resemble a bird's beak. Originating from the mountainous regions of Asia, Pedicularis wilhelmsiana is highly sought after by plant collectors for its striking appearance and ability to attract pollinators with its nectar-rich blooms.
Every 5–7 days
Partial shade to full sun
50–75°F
40–60%
At a glance
How do you care for Giant Lousewort?
Water Giant Lousewort every 5–7 days, letting the top layer of soil dry out between waterings, and give it partial shade to full sun. It prefers temperatures of 50–75°F (10–24°C) and 40–60% humidity. Fertilize it every 6 months during the growing season.
What Is the Giant Lousewort?
Giant Lousewort (Pedicularis wilhelmsiana) belongs to the Orobanchaceae family within the Pedicularis genus. Giant Lousewort is native to China, Mongolia, Russia. Giant Lousewort is also known as Wilhelms' lousewort.
Giant Lousewort displays a clumping herbaceous perennial growth habit, reaching up to 1.5 ft tall with a spread of approximately 1 ft. Giant Lousewort produces tubular flowers in shades of pink, purple, or white.
Leaf size: approximately 4 inches.
How Often Should You Water a Giant Lousewort?
Pedicularis wilhelmsiana requires watering every 5–7 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 5–7 days
Let soil partially dry between waterings
What Light Does the Giant Lousewort Need?
Giant Lousewort thrives in partial shade to full sun.
Light Requirement
Partial shade to full sun
What Temperature and Humidity Does the Giant Lousewort Prefer?
Pedicularis wilhelmsiana grows best at temperatures of 50–75°F. Giant Lousewort prefers humidity levels of 40–60%.
Temperature
50–75°F
Humidity
40–60%
What Soil Mix Works Best for a Giant Lousewort?
Well-draining, slightly acidic soil with good organic content. Good drainage is essential for Giant Lousewort to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Giant Lousewort?
Feed Giant Lousewort 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 Giant Lousewort?
Repot every 1-2 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 Giant Lousewort?
Giant Lousewort can be propagated through seeds, division. Similar propagation techniques also apply to marsh lousewort plant care, which shares the same genus.
Is the Giant Lousewort Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Giant Lousewort, 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 Giant Lousewort?
Giant Lousewort is susceptible to aphids, spider mites. 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 Giant Lousewort Need?
Giant Lousewort grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. Giant Lousewort is native to China, Mongolia, Russia. In cooler regions, grow Giant Lousewort as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 12a
Keep exploring plants
Giant Lousewort 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 Pedicularis genus — compare its care with other Pedicularis species on PlantoScan.
Pedicularis is part of the Orobanchaceae plant family — browse all Orobanchaceae genera and species.
Giant Lousewort thrives in bright light and direct sun — see other bright-light plants.
More Pedicularis Species
Other Pedicularis species in PlantoScan's care catalogue share similar watering, light, and soil preferences:
Sources
- Scientific name & taxonomy: Pedicularis wilhelmsiana Fisch. ex M.Bieb., family Orobanchaceae (first published in Fl. Taur.-Caucas. 3: 412 (1819)) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Giant Lousewort, 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.
- Photo: Jacek Pietruszewski, CC BY 4.0, iNaturalist — original.
- 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.
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