There are four types of lights that can be used in greenhouses:
Incandescent light
High intensity fluorescent light
High intensity discharge (HID) light
Light emitting diode (LED) light
INCANDESCENT LIGHT BULBS FOR GREENHOUSE
Incandescent light bulbs are electric lights which heats up to a temperature high enough to make it glow with visible light. Because of the heat they produce you must not place them close to foliage. It is a good option to increase the day length.
Unfortunately, they don’t provide sufficient light for most greenhouse applications. It is a very easy lighting option to install and it is a good source of red wavelengths.
HIGH INTENSITY FLUORESCENT FOR GREENHOUSE
In comparison to incandescent bulbs, fluorescent light is more efficient in converting electricity into light without waste of heat. The color spectrum of standard cool white fluorescent bulbs is high in blue and low in red. Although, they do provide a full white light spectrum.
A standard fluorescent bulb knows as T12 is sufficient for houseplants, starting seeds but is weak in light intensity. A narrower T5 provides three times more light than T12 and is in both warm and cold spectrum.
Fluorescent light is a good option for a greenhouse with low natural light. It is also suitable for the propagating areas or growth rooms. Large spaces can benefit from fluorescent bulbs efficiency.
LED LIGHT FOR GREENHOUSE
LED lights are more expensive to purchase than fluorescent light but use half the electricity and last up to five times longer. Also, their light intensity is far greater and they come in full spectrum light. commercial grow lights are small in size and are really easy to install.
WILL LED LIGHTS HELP PLANTS GROW?
LED lights help plant growth because they maximize blue and red lights to provide a balance for plants. They don’t provide green and yellow light and only optimize the light spectrum appropriate for photosynthesis.greenhouse grow lights are helpful in all stages of plant growth.
WHAT LIGHT SOURCE IS RECOMMENDED FOR A GREENHOUSE?
HID is a recommended light source for a greenhouse as it is very economical. Many growers opt for HID as the best lights to provide supplemental greenhouse light. These powerful led grow light are very efficient at converting electricity to light and are good at increasing light intensity.
There are two types of HID:

High-pressure sodium (HPS) bulbs – these are rich in red spectrum and are used to promote growth and flowering.
Metal Halide (MH) bulbs – these provide more blue light and are ideal to support vegetative growth. Use them in the early phase of plant’s life. In comparison to HPS, their spectrum is more balanced.
However, there are two disadvantages with this light source. First, you need to install them on the large heavy ballasts which come separately from the light fixtures. These ballasts are quite bulky and take a lot of space, so it is not as practical as in comparison to small-sized hydroponics led grow lights.

Second, HID lights produce a significant amount of heat. Therefore, you need to place them 30-36 inches (76-91 cm) away from the plants which effects the lighting efficiency. Also, in comparison to other options, HID lights are more expensive to operate.