Temperature

Haworthias grow best in a subtropical area with mild to warm winter days (14~25 °C) and cool to cold winter nights (preferably 4~10 ºC). When the temperature drops below 4 °C, the plants are subject to freezing injury. While keeping the ambient air flowing, Using air conditioners and heating mats, and creating thermal insulated growing areas are efficient methods to protect the plants from the cold.

A thermometer that tracks min/max temperatures of day.Atelier Sakura @ Palo Alto, CA
A thermometer that tracks min/max temperatures of day.

In summer Haworthias prefer warm to hot days (25~38 ºC) with mild to cool nights (14~20 ºC). They do not like high overnight temperatures above 24 ºC. This is because they collect carbon dioxide for photosynthesis at night, and the collection can be inhibited by high temperatures. Air conditioners and fans can be used for keeping the plants cool.