[citation needed] A simple and effective sterilizing method commonly used today is autoclaving: heating the substance being sterilized to 121 °C (250 °F) for 15 minutes in a pressured system.
[citation needed] If autoclaving is not possible because of lack of equipment, or the need to sterilize something that will not withstand the higher temperature, unpressurized heating for a prolonged period at a temperature of up to 100 °C (212 °F), the boiling point of water, may be used.
During the resting periods the substance being sterilized is kept in a moist environment at a warm room temperature, conducive to germination of the spores.
But it is not considered completely reliable — some spores may survive and later germinate and multiply.
It is not often used today, but is used for sterilizing items that cannot withstand pressurized heating, such as plant seeds.