The inflorescence of Aloe melanacantha is usually simple. A single raceme of up to 1 m grows on a brown peduncle that is flattened lower down, up to 2 cm in diameter. Sterile bracts, oval in shape with pointed tips are present on it below the inflorescence.
The densely flowered raceme is brightly scarlet-red, the perianth tubes turning yellow upon opening. The buds above the open flowers cohere tightly in a narrow cylinder, pale greenish grey in colour. The perianth is between circular and triangular in cross-section, slightly curved and about 4,5 cm long. The inner segment tips are green-brown and pale-keeled, the outer ones green.
The anthers are exserted, the inner three first; the stigma as well. The lowest pedicels are the longest, about 1,5 cm but still to elongate during fruiting.
Flowering is mostly seen late in autumn and early in winter (Reynolds, 1974; Van Wyk and Smith, 2003).