Aloe squarrosa aka Shark Tooth Aloe

Aloe squarrosa is a slow-growing succulent that typically reaches 10-30 cm (4-12 inches) in height with a similar spread when mature. The plant develops thin stems measuring 10-20 cm long and 7-8 mm thick, with branches forming from the base. Expect the plant to reach its mature size in 5-10 years. It forms a rounded, spreading habit with rosettes of recurved leaves concentrated at stem tips.

Aloe squarrosa prefers daytime temperatures of 15-27°C (60-80°F) and nighttime temperatures of 13-21°C (55-70°F). Never expose this plant to temperatures below 4°C (40°F) as it is highly frost-sensitive. In winter, maintain minimum temperatures of 10-15°C. This plant cannot be grown outdoors year-round in temperate climates and requires heated greenhouse conditions or indoor cultivation in cooler regions.

This plant has distinct active and dormant periods. Spring and autumn are the main growing seasons—water moderately and apply liquid fertilizer monthly from May to August. During winter dormancy, water very sparingly to prevent rot, and cease all fertilization. In summer, provide some afternoon shade in hot climates to prevent leaf scorch. The plant is best propagated in spring or early summer when actively growing.

When conditions are optimal, Aloe squarrosa produces pendant, curved flower spikes up to 35 inches tall with cylindrical racemes of tubular flowers. The blooms are red to light orange with distinctive green tips, measuring about 20-25 mm long. Flowering typically occurs in autumn. However, container-grown plants rarely bloom indoors—flowering is more common when plants are grown in ideal greenhouse conditions or outdoors in suitable climates.

The easiest method is separating offsets (pups) in spring or early summer. Look for offsets with their own roots and a few inches of growth. Gently twist or cut them from the mother plant, let them dry for a day to form a callus, then plant in well-draining cactus soil. You can also propagate from leaf cuttings (allow to callus first) or from seed sown when ripe. Place new plants in bright, indirect light and water sparingly until established.

Repot Aloe squarrosa every 2 years in spring to refresh the soil and provide room for growth. Move to a slightly larger container only when roots emerge from drainage holes. Use a terracotta pot with excellent drainage and fill with cactus/succulent potting mix amended with perlite or grit. After repotting, place in bright, indirect light and water sparingly for the first few weeks to allow roots to establish.

Aloe squarrosa can grow outdoors year-round only in USDA zones 9b-11 where temperatures stay above 4°C (40°F). It's ideal for Mediterranean, desert, and xeriscape gardens in frost-free areas. In cooler climates, grow it outdoors in containers during summer and bring inside before frost. Position in full sun with some afternoon shade protection in very hot regions. The plant is native to Socotra's limestone cliffs and thrives in similar dry, warm conditions.

Aloe squarrosa requires minimal pruning. The lower leaves naturally die and fall off as the plant grows, keeping foliage concentrated at the stem tips—this is normal and not a sign of problems. Simply remove any completely dried, dead leaves by gently pulling them away. Use clean, sharp scissors to trim damaged or diseased leaves at the base. Remove spent flower stalks after blooming. The leaf margins have sharp teeth, so wear gloves when handling.

The main pests are mealybugs—small white insects that feed on plant sap. Remove them by wiping with rubbing alcohol on a cotton swab. Scale insects can also be problematic. Spider mites, aphids, slugs, and snails may occasionally attack. The most common disease is root rot from overwatering—prevent this by using well-draining soil and allowing it to dry completely between waterings. Other potential issues include aloe mites, aloe rust, aloe scale, and chlorosis.

Yellow leaves typically indicate overwatering or poor drainage—this species is extremely susceptible to root rot. Check that soil dries completely between waterings and ensure the pot has drainage holes. Other causes include too little light (move to brighter location), nutrient deficiency (apply diluted fertilizer in growing season), or natural aging of lower leaves. If yellowing is accompanied by soft, mushy stems, root rot has likely set in—remove affected parts and repot in fresh, dry soil.

Brown leaf tips or edges usually indicate sunburn from too much direct afternoon sun—provide some shade during the hottest part of the day. Brown, mushy leaves suggest overwatering and potential root rot. Completely dry, brown lower leaves are normal as part of the plant's natural growth pattern. Cold damage can also cause browning—keep temperatures above 10°C. If the browning is spreading, check roots for rot and adjust watering immediately.

Aloe squarrosa itself doesn't have named cultivars, but it's often confused with Aloe juvenna (Tiger Tooth Aloe) from Kenya. The key differences: A. squarrosa has longer, recurved (backward-curving) leaves concentrated at stem tips, while A. juvenna has shorter, straight triangular leaves retained along the entire stem. There is a natural hybrid, Aloe × buzairiensis (A. perryi × A. squarrosa), found only on Socotra where both parent species grow.

Caring for Shark Tooth Aloe is a breeze, as it is highly adaptable and forgiving to minor neglect.

Shark Tooth Aloe’s native range is Southern Africa to India.

Shark Tooth Aloe does best in dry soil and should only be watered sparingly.

When growing the Shark Tooth Aloe, it's important to use a potting soil that is well-draining and does not retain excessive moisture. An optimal soil mix should contain a high proportion of perlite or vermiculite for good drainage and some organic matter for nourishment. Simply add a few scoops of perlite to regular cactus soil to achieve this.

Shark Tooth Aloe requires abundant, bright, and direct light to thrive. The best placement for this plant is within one foot of a window to ensure it receives enough light. If you live in an area with more extreme weather, such as hot summers or cold winters, you may need to adjust the placement of the plant accordingly. During hot summer months, it is important to place the plant away from full sun, as this can cause the leaves to yellow or burn. During cold winter months, it is best to move the plant closer to the window to take advantage of the extra light that can help it survive. By keeping an eye on the current weather in your area, you can make sure your Jemen Aloe is always in the right place to thrive.

Shark Tooth Aloe plants thrive in dry environments, however, if you choose to provide extra humidity or mist your plant, the lingering water on the leaves can create an ideal environment for certain types of harmful fungi.

The Shark Tooth Aloe grows at a slow pace and doesn't require any supplementary fertilizers. By renewing its potting soil once a year, it should receive enough nourishment. Remember, plants obtain their energy from sunlight, not fertilizers.

Ploi lacks confirmed information on the toxicity of this plant. If you, a relative, or your pet accidentally consume plant material with unknown toxicity, it's best to consult a medical expert.