So, what do you need to know about temperature ranges in order to maintain a garden?. Firstly, understand your climate. Does it rain a lot but rarely freeze? Does it get very hot and dry during the summer months?. Does it freeze or snow on a regular basis? Secondly, understand how the sun and the environment affect temperatures. If plants are in an exposed area where they get extremes of wind, sun or snow they may not thrive.
Most plants do well in the mid-range of temperatures, about 10-21 C, in a stable environment. If there is a drastic drop in temperature, plants may freeze (frozen plant tissue does not photosynthesize or conduct nutrients well!). If it gets too hot plants may also die as they wilt due to the rapid evaporation of water from their leaves. Their leaves get sunburned and shrivel.
Any long-term exposure to high heat or low temperatures will adversely affect plants that are not used to it (cacti obviously do well in a hot desert), so protect them by surveying their location, moving them if needed, and checking on their health frequently.