Species · genus Mammillaria · Cactaceae

Twin-spine Cactus

Mammillaria geminispina Haw.

Also known as: Whitey

Growth habit

succulent subshrub

Native range

Mexico Gulf, Mexico Northeast

Mammillaria geminispina — reference photo — no rights reserved · CC0

Cultivars of M. geminispina

The named forms growers keep — each with its own page, each honest about how much we know.

No named cultivars catalogued under M. geminispina yet. When growers document a stable, named form, it earns its own page here.

Guide

The species-level account. Cultivar pages build on this and say where they differ.

The Twin-Spined Cactus

Mammillaria geminispina, sometimes called whitey, is a clump-forming cactus of the Cactaceae family. It builds a mound of clustered stems studded with white spines, topped in season by small pink-striped flowers.

Source: RHS

A Mexican Native

This species comes from northeastern Mexico, reaching toward Veracruz, where it grows in desert and dry shrubland. It was first described by Haworth in 1824, and over the decades has collected a long tail of synonyms as botanists reclassified and renamed it.

Source: Kew

Sun, Grit, And Restraint

Give this cactus full sun, or under glass bright filtered light, in a well-drained loam or sandy mix, and keep humidity low. Water moderately while it is in active growth and feed every two or three weeks with a balanced liquid feed, then let it rest nearly dry through winter. It tolerates cool conditions down to around 1 to 5°C but will not survive a hard frost.

Source: RHS

Seed Or Offsets

New plants can be raised from seed sown at 19 to 24°C in early spring, or more simply by removing the offsets the clumping stems readily produce.

Source: RHS

Spines And Stem Clusters

The stems cluster into a mound that can reach about 20cm in height, each covered in short white radial spines set against longer brown central ones. In flower, it carries small blooms around 1.5cm across, white with stripes of deep pink.

Source: RHS

Watch For Mealybugs

Mealybugs are the main pest to watch for on this species. Otherwise it is generally free of disease.

Source: RHS

Little Fuss Needed

This cactus needs no pruning. Left in a container on a patio or under glass, it simply builds its mound of stems over years, reaching maturity somewhere between five and ten years.

Source: RHS

Care recipe

The species record — the baseline every cultivar inherits unless it says otherwise.

Care notes are early — not yet verified

Light: ai:claude-opus-4-8
Water: ai:claude-opus-4-8 (range 14-28d)
Humidity: ai:claude-opus-4-8
Soil: ai:claude-fable-5
Care: ai:claude-fable-5

Light

Direct sun

Water

≈ every 28 days

Humidity

Low — average room

Temperature

7–32 °C

Soil mix

Gritty, fast-draining cactus mix

Propagation

Offsets separated and rooted after callusing

Fertilizing

Dilute low-nitrogen cactus feed in spring and summer

Growth rate

Slow

Flowering

Deep pink flowers ringing the crown in spring

ToxicityAuthoritative · species

Not yet documented

This is where toxicity lives — every cultivar of this species inherits it and none can override it.

Reference images

Every image credited. Licenses link to their deeds.

Sources: ai:claude-opus-4-8 · ai:claude-opus-4-8 (range 14-28d) · ai:claude-fable-5

Kept true by its growers

Every fact here carries its source. Grow Twin-spine Cactus yourself? What you’ve observed — how it drinks, how it holds its color, a name that’s off — and a clear photo of your plant are exactly what keep this page honest. Contributions are reviewed before anything changes.