Photo: Robin WhiteCC BY 4.0via iNaturalistresized / cropped
Fernow's Cactus Plant Care
Harrisia fernowii Britton
Updated · Sources · How we source care data
This unique cactus species is recognized by its slender, elongated stems covered in sharp spines, originating from the coastal regions of Brazil. Plant collectors are drawn to Harrisia fernowii for its striking architectural form and beautiful white nocturnal flowers that bloom in summer.
Every 14–21 days
Full sun
50–90°F
10–40%
At a glance
How do you care for Fernow's Cactus?
Water Fernow's Cactus every 14–21 days, letting the top layer of soil dry out between waterings, and give it full sun. It prefers temperatures of 50–90°F (10–32°C) and 10–40% humidity. Fertilize it every 8 months during the growing season.
Where Is the Fernow's Cactus Native To?
What Is the Fernow's Cactus?
Fernow's Cactus (Harrisia fernowii) belongs to the Cactaceae family within the Harrisia genus. Fernow's Cactus is native to Cuba. Fernow's Cactus is also known as Climbing Cactus.
Fernow's Cactus displays a columnar, branching cactus growth habit, reaching up to 6 ft tall with a spread of approximately 2 ft. Fernow's Cactus produces large white nocturnal blooms.
Leaf size: approximately 2 inches.
How Often Should You Water a Fernow's Cactus?
Harrisia fernowii requires watering every 14–21 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 14–21 days
Let soil partially dry between waterings
What Light Does the Fernow's Cactus Need?
Fernow's Cactus thrives in full sun.
Light Requirement
Full sun
What Temperature and Humidity Does the Fernow's Cactus Prefer?
Harrisia fernowii grows best at temperatures of 50–90°F. Fernow's Cactus prefers humidity levels of 10–40%.
Temperature
50–90°F
Humidity
10–40%
What Soil Mix Works Best for a Fernow's Cactus?
Sandy, well-draining cactus mix with perlite and coarse sand. Good drainage is essential for Fernow's Cactus to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Fernow's Cactus?
Feed Fernow's Cactus every 8 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 8 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 Fernow's Cactus?
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 Fernow's Cactus?
Fernow's Cactus can be propagated through stem cuttings, offsets. Similar propagation techniques also apply to earle's cereus plant care, which shares the same genus.
Is the Fernow's Cactus Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Fernow's Cactus, 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 Fernow's Cactus?
Fernow's Cactus is susceptible to spider mites, scale insects. 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 Fernow's Cactus Need?
Fernow's Cactus grows outdoors in USDA Zone 10a – 11b. It survives winters down to planting zone 10a. Fernow's Cactus is native to Cuba. In cooler regions, grow Fernow's Cactus as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 10a – 11b
Keep exploring plants
Fernow's Cactus 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 Harrisia genus — compare its care with other Harrisia species on PlantoScan.
Harrisia is part of the Cactaceae plant family — browse all Cactaceae genera and species.
Fernow's Cactus thrives in bright light and direct sun — see other bright-light plants.
More Harrisia Species
Other Harrisia species in PlantoScan's care catalogue share similar watering, light, and soil preferences:
Sources
- Scientific name & taxonomy: Harrisia fernowii Britton, family Cactaceae (first published in in Bull. Torrey Bot. Club 35: 562. 1908.) — World Flora Online record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Fernow's Cactus, 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: Robin White, CC BY 4.0, iNaturalist — original.
- Hardiness zone: USDA Zone 10a – 11b, estimated from the plant's typical growing conditions.
- 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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