Temperature monitoring is very important to ensuring a successful garden. When growing indoors, it's easy for plants to get too hot under the lights or too cold when the lights are off, and many plants will not tolerate wide variances in temperature. Temperature monitoring allows the gardener regulate the temperature of the grow space, and ensure the conditions remain ideal for productivity. Thermostats are used to automatically monitor temperatures, and can be used on heaters or extractor fans to control the temperature of the room.