Zebra haworthia

Identification and origin

Haworthiopsis attenuata belongs to the Asphodelaceae, the same family as aloes. It is native to the Cape Provinces of South Africa, where it grows in harsh conditions, often half buried in sand or shaded by larger succulents and rocks.

First placed in Aloe, then in the genus Haworthia, named in honor of the English botanist Adrian Hardy Haworth, it was moved in 2013 to the genus Haworthiopsis, which groups the species with thick, rough leaves. The epithet attenuata, “thinned,” refers to its leaves, which taper to a fine point.

Stemless, it forms compact, star-shaped rosettes that produce offsets and eventually spread into a small carpet. It reaches 4–12 in tall and 6 in – 2 ft wide. Its stiff, narrow, pointed, dark green leaves carry small white bumps, called tubercles, lined up in horizontal bands on both surfaces, which give the plant its name. It is often confused with the rarer Haworthiopsis fasciata, whose upper leaf surface is smooth. From late spring to early summer, a long, thin stalk carries small tubular flowers, white to pale pink.

It grows slowly but can live up to fifty years. Forms in cultivation include f. caespitosa, with the white dots arranged in bands, ‘Enon’, a lime green miniature, and ‘Super Clone’.

Light

It prefers bright, filtered light with a few hours of direct sun. An east- or west-facing window is ideal. In a south-facing window, a sheer curtain keeps the leaf tips from browning: strong direct sun scorches the foliage.

It tolerates lower light than most succulents, but too little light soon shows: the leaves stretch, the rosette loses its compact shape and the white markings fade. Good light, on the other hand, produces tight rosettes and deeper colors, sometimes with other tints. It grows well under strong grow lights.

Watering

Let the top 1–1 in of the mix dry out before watering, then water thoroughly and let all the excess drain away. Empty the saucer. Avoid wetting the center of the rosette: water sitting between the leaves causes rot.

During active growth in spring and summer, the mix dries faster and waterings come closer together. In winter, space them out considerably. Mix that stays wet too long, especially when it is cool, the light is low or the plant is resting, is the leading cause of root rot. No extra humidity is needed: ordinary household air suits it.

Potting mix

Use a cactus and succulent mix, or a good potting mix blended with an equal volume of drainage material: perlite, aquarium gravel, poultry grit or pumice. Avoid sand, which is too fine and clogs the mix. Peat-based mixes break down within a few years and become unhealthy.

A shallow, terra-cotta pot with a drainage hole is ideal, since it lets moisture evaporate. Feed with a cactus fertilizer during the growing season only.

Temperature

It grows best between 61 °F and 81 °F, and handles heat well up to about 95 °F. Do not let it drop below 50 °F: cold damages the leaves. A plant kept dry can briefly tolerate 41 °F, but it does not survive frost. Keep it away from cold air currents.

It can spend the summer outdoors once frost is over; in the ground it is grown only in USDA zones 9a to 11b. When moving it out, get it used to the sun gradually over a few weeks, since a plant that spent the winter indoors sunburns easily. In hot weather, keep it in partial shade in an airy spot.

Repotting

Because it grows slowly, it can stay in the same pot for years. Still, refresh the mix every two to three years. Choose a pot whose volume matches the root system: an oversized pot holds water too long. When the clump outgrows its pot, move it to one only slightly wider rather than putting a small plant into a large container.

Pruning

No pruning is needed: the plant requires very little maintenance. The only useful cuts are removing rotted roots during repotting and separating offsets when the clump gets too crowded.

Propagation

The easiest method is to separate the offsets, or pups, that form at the base of mature rosettes. Many already have roots; some fall away on their own when the clump is unpotted, while others need to be cut or snapped off. If separating them leaves a wound, let it air-dry for a few days before potting to keep soil organisms out.

You can also root a leaf cutting: take a mature leaf with a little stem tissue attached, let the wound dry, then set it on a fast-draining mix; one or more small rosettes slowly form. Growing from seed is uncommon because seed is hard to find; sown on a well-drained mix kept moist, it germinates in one to two weeks.

Common problems

• Root or crown rot: mix that stays too wet, especially combined with low light. Signs: growth stops, leaves get smaller or shrivel. Unpot the plant, cut off rotted roots, leave it out of the pot for a week, then repot in fresh mix and water sparingly.
• Stretched leaves, pale markings: not enough light.
• Brown or bleached patches: sunscald from direct sun, or leaf spots and fungal problems encouraged by soggy mix or water left on the leaves.
• White, cottony clusters: mealybugs. Dab them with a cotton swab dipped in isopropyl alcohol at no more than 70 percent strength, after testing on a small part of the plant. Also watch for scale insects.

The same symptom can have several causes: always check the light, the moisture of the mix, the temperature and the condition of the roots.

Toxicity

No toxicity has been reported. Veterinary references list zebra plant as non-toxic to dogs, cats and horses, and it is considered safe for people. That makes it a good choice for homes with pets.