How often should I water my cactus?

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

Why is my cactus turning yellow?

Yellowing often indicates too much water or a lack of sufficient sunlight.

Plant guide

Cactus.

Cactus Linn. ex Kuntze, 1891

Pronounced kak-TAY-see-ee

saguaro — Photo by Bob Miller (CC BY) via iNaturalist

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 sun
Water: Every 14 to 30 days
Mature size: Varies by species
Growth rate: Slow
Hardiness: USDA 9 to 11
Bloom time: Mid to late spring

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: 5 to 35°C
Humidity: 10 to 40%
Drought tolerance: High
Lifespan: Perennial, can live for decades.
Fragrance: Light
Deer and rabbits: High

Signs it needs repotting

Roots growing out of the drainage hole.
The plant has become top heavy and unstable.
Soil has broken down and no longer drains well.

Safety

People: Most cacti are not toxic, but the spines can cause significant mechanical injury and secondary infections.
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 children because the sharp spines pose a serious risk of puncture wounds.
Contact allergens: Handling the plant can cause skin irritation from glochids or spines.
Airborne allergens: Pollen from some species may trigger mild seasonal allergies.
Edibility: Only specific species like Opuntia produce edible fruit, and all spines must be removed carefully before consumption.

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: yellow, pink, white, red, 2 to 10cm
Fruit: red, purple, yellow, Late summer

Problems to watch for

MealybugsCommon
Root RotCommon
Scale InsectsUncommon
Spider MitesUncommon

By symptom

Plant problems by symptom

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Growing it

Propagation: cuttings, seed, division
When to plant: Spring, Summer
Overwintering: Move to a cool, bright location and stop watering almost entirely to induce dormancy. Keep the plant dry to prevent rot during the cold months.
In containers: Cacti grow exceptionally well in containers as long as the pot has drainage holes and a gritty soil mix.

Stem Cuttings

1. Cut a healthy pad or stem segment.
2. Let the cut end callous over for 1 week.
3. Place the calloused end into dry succulent soil.
4. Wait 2 weeks before watering lightly.

Group cacti with other succulents that prefer gritty, fast draining soil to prevent accidental overwatering.

Grows well with

Agave · They share similar water and light requirements in a desert garden.
Aloe · These plants thrive in the same well draining soil conditions.

Similar species

Euphorbia · Often mistaken for cacti due to their succulent stems and spines.

Science

Family: Cactaceae
Genus: Cactus
Order: Caryophyllales
Class: Magnoliopsida
Native range: Americas, from Canada to Patagonia.
Conservation: Many wild cactus species are protected under CITES due to illegal collection for the ornamental trade.

Cacti survive in arid environments by using crassulacean acid metabolism to minimize water loss during photosynthesis.

Value to wildlife: nectar source, provides shelter
Pollinators: bees, butterflies, moths
Uses: ornamental, xeriscaping, edible fruit

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, usually every 2 to 4 weeks depending on the season.
Why is my cactus turning yellow?: Yellowing often indicates too much water or a lack of sufficient sunlight.

Where the name comes from

The name comes from the Ancient Greek word kaktos, which was used for a spiny plant. Scientific classification falls under the Cactaceae family.

Good to know

Cacti are succulents that store water in their stems.
Some cacti only bloom at night to attract moths.
The spines are actually modified leaves.

Also in

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This guide was generated with AI on September 26, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.