How often should I water my cactus?

Water only when the soil is completely dry, which is usually every 2 to 4 weeks depending on the season.

Do cacti need direct sun?

Most cacti thrive in bright, direct sunlight for at least 6 hours a day.

Plant guide

Cactus.

Cactus Linn. ex Kuntze, 1891

Pronounced kak-TAY-see-ee

Cacti are fascinating succulents adapted to survive in arid environments. They store water in their thick stems and have modified leaves called spines. These plants bring a unique architectural look to any sunny space.

At a glance

Care level: Easy
Plant type: Succulent
Light: Full sun
Indoor light: direct
Water: Every 14 to 30 days
Mature size: Varies by species
Growth rate: slow
Hardiness: USDA 9 to 11
Bloom time: Spring to summer

Care

Provide plenty of direct sunlight and ensure the soil dries out completely between waterings. Watch for shriveling stems which indicate thirst, or mushy spots that suggest rot from too much moisture.

Watering: Allow the soil to dry completely before watering again.
Feeding: Use a balanced cactus fertilizer during the active growing season.
Pruning: Only prune to remove dead or damaged growth using sterilized tools.
Repotting: Repot only when the plant has clearly outgrown its current container.
Soil: Well-draining cactus mix
Soil pH: 6.0 to 7.5
Temperature: 10 to 35°C
Humidity: 10 to 40%
Drought tolerance: high
Lifespan: Perennial, typically 10 to 50 plus years.
Deer and rabbits: high

Signs it needs repotting

Roots growing out of the drainage holes.
The plant has stopped growing during the active season.
The soil drains too quickly or has pulled away from the pot edges.

Safety

People: Most cacti are non toxic, but their physical spines pose a significant mechanical injury risk.
Pets: Most cacti are non-toxic to pets, though their sharp spines can cause physical injury if touched or ingested.
Children: Keep cacti out of reach of small children because their sharp spines can cause painful punctures and infections.
Contact allergens: The fine, hair like spines called glochids can easily embed in skin and cause persistent irritation.
Airborne allergens: Some people may experience mild respiratory irritation if they inhale dust from dried cactus debris.
Edibility: Many cacti have spines that cause severe injury if ingested or handled improperly.

How to identify it

fleshy stems for water storage
spines instead of true leaves
distinct areoles where spines grow
thick waxy outer skin

Height: 0.05 to 2m
Spread: 0.05 to 1m
Leaves: green, blue-green, evergreen
Flowers: pink, yellow, white, red, 1 to 15cm
Fruit: red, purple, yellow, Late summer

Common problems

Root rot — This occurs when the soil stays too wet for too long, causing the roots to decay.
Mealybugs — These small white insects hide in crevices and suck sap from the plant.

Growing it

Propagation: cuttings, seed, offsets
When to plant: spring
Overwintering: Move plants indoors or to a frost free location before temperatures drop. Keep them cool and dry throughout the winter months to encourage dormancy.
In containers: Cacti grow very well in pots, provided the container has excellent drainage and is not much larger than the root ball.

Stem Cuttings

Cut a healthy segment from the parent plant.
Let the cut end callous over in a dry place for a few days.
Place the calloused end into well draining cactus soil.
Wait a few weeks before watering to allow roots to form.

Group plants with identical water needs together to prevent accidental overwatering of your cacti.

Grows well with

Agave — They share similar water and light requirements for a cohesive desert look.
Sedum — These low growing succulents provide a nice textural contrast to upright cacti.

Similar species

Euphorbia — These plants look like cacti but often have toxic milky sap.

Science

Family: Cactaceae
Genus: Cactus
Order: Caryophyllales
Class: Magnoliopsida
Native range: The Americas, ranging from Canada to Patagonia.
Conservation: Many wild cactus species are threatened by illegal collection and habitat loss, so always buy nursery grown plants.

Cacti survive in arid environments by using specialized stems to store water and spines to shade the plant surface.

Value to wildlife: nectar source, nesting habitat
Pollinators: bees, moths, hummingbirds
Uses: ornamental houseplant, xeriscaping, desert garden accent

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
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 my cactus?: Water only when the soil is completely dry, which is usually every 2 to 4 weeks depending on the season.
Do cacti need direct sun?: Most cacti thrive in bright, direct sunlight for at least 6 hours a day.

Where the name comes from

The name comes from the ancient Greek word kaktos, which was used to describe a spiny plant.

Good to know

Cacti are native almost exclusively to the Americas.
The spines on a cactus are actually modified leaves.
Some cacti can live for over 100 years in the wild.
Cacti perform photosynthesis at night to reduce water loss.

Is your cactus looking unwell?

This page is a general guide. Pocket Botanist diagnoses problems from a photo of your actual plant, works out watering for your light and conditions, and reminds you when care is due.

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