How often should I water it?

Water sparingly during the growing season and keep it completely dry throughout the winter.

Does it need full sun?

Yes, it requires bright, direct sunlight to maintain its compact shape and healthy spine growth.

Plant guide

Coast barrel cactus.

Ferocactus viridescens

Pronounced feh-roh-KAK-tus veer-ih-DESS-ens

Also known as Coast Barrel Cactus, San Diego Barrel Cactus, coastal barrel cactus, green-stem viznaga, keg cactus, small barrel cactus

San Diego Barrel Cactus — Photo by Millie Basden (CC BY) via iNaturalist

This charming little barrel cactus is a real gem from the coastal regions of Southern California and Baja. It stays quite compact compared to its larger cousins, making it a perfect fit for a sunny windowsill. You will love its sturdy, ribbed structure and those striking, colorful spines.

Another photo of Coast barrel cactus — Photo by CK2AZ (CC BY) via iNaturalist

At a glance

Care level: Easy
Plant type: Succulent
Light: Full sun
Indoor light: Direct sun
Water: Every 14 to 30 days
Mature size: 12 inches tall
Growth rate: Slow
Hardiness: USDA 9 to 11
Bloom time: Late spring to early summer

Care

Give this cactus as much direct sun as you possibly can to keep it healthy and compact. Let the soil dry out completely between waterings, and watch for shriveling as a sign it is thirsty. Ensure your pot has excellent drainage to keep the roots happy and rot-free.

Watering: Water sparingly during the growing season and keep it almost dry throughout the winter months.
Feeding: Feed with a balanced, low-nitrogen fertilizer diluted to half strength during the active growing season.
Pruning: Pruning is rarely needed, but you can carefully remove any dead or damaged tissue with sterilized shears.
Repotting: Repot only when the plant has clearly outgrown its container, using a pot just slightly larger than the current one.
Soil: Well-draining cactus and succulent mix
Soil pH: 6.0 to 7.5
Temperature: -4 to 45°C
Humidity: 10 to 40%
Drought tolerance: High
Lifespan: Perennial, can live for several decades with proper care.
Deer and rabbits: High

Signs it needs repotting

Roots growing out of the drainage holes.
The cactus has become top heavy and unstable in its pot.
Growth has slowed significantly over several years.

Safety

People: The plant is not toxic, but its sharp spines pose a significant physical injury risk.
Pets: This plant is generally considered non-toxic to cats and dogs, though its sharp spines pose a physical injury risk.
Children: Keep this plant well out of reach of children due to its extremely sharp and dangerous spines.
Contact allergens: The sharp spines can cause mechanical skin irritation or puncture wounds.
Airborne allergens: There are no known respiratory allergens associated with this plant.
Edibility: While the fruit is technically edible, it is often dry and lacks flavor, so it is best left for wildlife.

How to identify it

Globular to flattened stem shape
Prominent ribs with sharp spines
Spines often turn reddish or yellow
Yellow to greenish cup shaped flowers

Height: 0.15 to 0.3m
Spread: 0.15 to 0.35m
Leaves: green, evergreen
Flowers: yellow, greenish-yellow, 3 to 5cm
Fruit: red, Late summer

Problems to watch for

Root rot · This occurs when the soil stays too wet for too long, especially in cooler weather.
Mealybugs · These small white insects hide in the crevices between ribs and suck plant sap.

By symptom

Plant problems by symptom

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Growing it

Propagation: seed
When to plant: spring, early summer
Overwintering: Keep the plant completely dry and in a bright location during winter. Ensure it is protected from freezing temperatures and excessive winter rain.
In containers: It grows very well in containers, provided you use a fast draining cactus mix and a pot with large drainage holes.

Seed Sowing

1. Sow seeds in a well draining cactus soil mix during spring.
2. Keep the soil lightly moist and warm until germination occurs.
3. Gradually reduce watering as the seedlings establish their root systems.

Group this cactus with other drought tolerant plants that do not require summer irrigation to prevent rot.

Grows well with

California Poppy · They share similar low water needs and create a lovely visual contrast.
Cleveland Sage · This shrub provides a nice backdrop and thrives in the same dry, sunny conditions.

Similar species

Golden Barrel Cactus · It has a similar barrel shape but grows much larger and has distinct golden spines.

Science

Family: Cactaceae
Genus: Ferocactus
Order: Caryophyllales
Class: Magnoliopsida
Native range: Coastal Southern California and northern Baja California.
Conservation: It is considered a sensitive species in parts of its range due to habitat loss from coastal development.

It survives in arid coastal scrub by storing water in its succulent stem and utilizing spines to shade its body from intense sun.

Value to wildlife: nectar source
Pollinators: bees
Uses: xeriscaping, container gardening, rock gardens

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 4/9
Soil reaction: 6/9
Light: 8/9
Temperature: 7/9
Moisture: 1/9
Nutrients: 2/9

Taxonomy resolved against GBIF.

Questions people ask

How often should I water it?: Water sparingly during the growing season and keep it completely dry throughout the winter.
Does it need full sun?: Yes, it requires bright, direct sunlight to maintain its compact shape and healthy spine growth.

Where the name comes from

Ferocactus comes from the Latin ferox meaning fierce, referring to its formidable spines. The specific epithet viridescens means becoming green.

Good to know

It is commonly called the Coast Barrel Cactus.
The species name viridescens refers to the greenish tint of its flowers.
It is one of the few barrel cacti that stays relatively small.
It thrives in the unique microclimate of coastal Southern California and Baja.

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This guide was generated with AI on October 19, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.