An attractive, large aloe that occurs in savanna and grassland, with very distinctive spreading branches and snake-like Inflorescences; and flowers filled with dark brown nectar, a characteristic shared by few other aloes.

Aloe castanea is well adapted to hot and dry conditions, with succulent leaves that help it to survive long dry seasons. This species has a strong stem and root system to support its heavy crown. This species often occurs in rocky outcrops in bushveld, which protect young seedlings during hot and dry seasons, and from grass fires. This species grows well in a wide range of soil types and conditions.

The leaves are succulent, usually smooth both sides, bluish-green with toothed margins, growing up to 1 m long and forming a rosette around the stem.

The inflorescence is a very long, simple spike, a single, unbranched flower stalk, up to 1 m long, with reddish brown, cup-shaped flowers that produce copious dark brown nectar. Usually producing 1 to 5 flower heads per rosette and the flower heads are usually crooked or carried at an angle with the tip pointing upwards.