With the advent of high tech plastics and simpler system design, this came about in the late 1970s. The energy saving poly greenhouse covers, the PVC pipe used in the feed systems, and the nutrient injector pumps & reservoir tanks were all made of types of plastic not available prior to the 1970s. The actual temperature for the particular plant you are growing will vary. For optimal growth, the amount of light your plants receive can be the difference between life and death. Too many lights can dry out your plants while too few can have your plants stretching desperately towards the lights. All plants respond differently to light depending on the intensity, wavelength and duration it receives. In areas where food is traditionally produced, but where fields are over crowded or stripped of their nutrients, hydroponics is a way food can be produced using a minimum of space and resources. Hydroponic growth leads to an increase in production over traditional farming in two ways. For one, hydroponic gardening just plain saves space. Insects such as spider mites can destroy your hydroponically grown produce. Spider mites like many pests can be terminated in several ways. The best way to avoid a spider mite infestation is by taking precautionary measures. Plants should be visually inspected weekly; this will help determine if there are any in your garden. Many people like to start with tomatoes or roses since they have many hardy varieties to choose from. Gardeners will also want to try using the blue and red spectrum lights to increase growth and the flowering of their plants. The temperature control units may also come in handy once you decide how many plants you want to grow in your space. The plant roots are suspended within the water by various designs and the crop obtains the food nutrients directly from the water, or from an air mist sprayed directly unto the plant roots. Hydroponics also requires the use growing media. Hydroponic systems use various mediums that are composed from relatively inert materials that have the ability to retain the food rich moisture and have the ability to physically support the plant roots.