All cacti are succulents, but not all succulents are cacti. The difference comes down to one feature: cacti have specialised structures called areoles, the small fuzzy or woolly cushions that produce spines, flowers, and new growth. If a plant has areoles, it is a cactus. If it stores water in fleshy tissues but has no areoles, it is a succulent but not a cactus.
That distinction matters more than it sounds. It tells you what climate the plant comes from, how much sun it can take, and how to water it without rotting the roots.
What Makes a Cactus a Cactus
The cactus family (Cactaceae) is a single botanical family of around 1,750 species, almost all native to the Americas. The defining feature is the areole, a small structure unique to cacti where spines, flowers, and side branches all emerge. Even cacti that look spineless, like some Astrophytum species, still have areoles, just without the spines.
Other cactus traits, but none of them definitive on their own:
- Spines instead of true leaves on most species. The body of the plant does the photosynthesis.
- Stems that store water and often have ribs or tubercles to allow expansion.
- Native almost exclusively to the Americas, with one exception (Rhipsalis baccifera, which also grows in Africa and Sri Lanka).
So a Saguaro, a Christmas Cactus, and a tiny Mammillaria are all cacti, even though they look very different, because they all have areoles.
What Counts as a Succulent
Succulent is not a botanical family but a description. A succulent is any plant with thickened, fleshy parts that store water. The category cuts across dozens of plant families, including Crassulaceae (Jade plants, Echeverias), Asphodelaceae (Aloes, Haworthias, Gasterias), Asparagaceae (sansevierias, agaves), and Apocynaceae (String of hearts, Hoyas).
Succulents come from arid and semi-arid regions all over the world: South Africa, Madagascar, the Canary Islands, Mexico, the southwestern United States. Different origins mean different care needs, even within the broader succulent label.
Examples of succulents that are not cacti: Aloe vera, Echeveria, Crassula ovata (Jade Plant), Haworthia, Sansevieria, Sempervivum, String of Pearls (Senecio rowleyanus), and Lithops.
Practical Differences in Care
Once you know whether a plant is a cactus or a non-cactus succulent, you can make better choices about light, water, and soil. The differences are smaller than people often think, but they are real.
Light
Most desert cacti want as much direct sun as you can give them, including unfiltered sun through a south facing window. Most non cactus succulents from arid regions also want bright light, but a few (especially Haworthia and Gasteria) come from shaded crevices and prefer bright indirect light rather than direct midday sun. Forest cacti like Rhipsalis and Schlumbergera (Christmas Cactus) are the major exception in the cactus family: they want bright indirect light, not direct sun.
Water
Both groups store water and tolerate drying out. Desert cacti are typically the most drought tolerant; some can go 4 to 8 weeks between waterings in winter without problems. Non cactus succulents vary more: a Haworthia or a small Echeveria still wants water roughly every 2 to 3 weeks in summer. Forest cacti are far thirstier than desert cacti and prefer to be watered like a typical houseplant during the growing season.
For both groups, the rule is the same: water thoroughly, let the compost dry out completely, then water again. Overwatering is the single most common reason these plants die. We see far more rotted cacti and succulents than dehydrated ones in our customer service messages.
Soil
Both want a free draining, low-organic mix. A standard cacti and succulent compost works for both. We use our own Desert Mix for the entire cacti and succulent collection at the nursery. A bagged multipurpose compost holds far too much water for either group and will rot the roots.
How to Tell at a Glance
If you are not sure whether a plant in front of you is a cactus or a non-cactus succulent, look for areoles. Spines or hairs growing from a small fuzzy cushion equals cactus. Smooth fleshy leaves or stems with no areoles equals non cactus succulent. The presence or absence of spines on its own is not enough to tell.
Some genuinely tricky cases: euphorbias like Euphorbia trigona and Euphorbia obesa look exactly like cacti but are not. They are succulents in the family Euphorbiaceae, with no areoles, and they bleed a milky white sap when cut, which true cacti never do. The sap is irritant. Worth knowing if you have one in the house.