Grow light gardening


Dear Master Gardener, I would like to know what kind of grow lights I need to install in a grow light garden. What does it mean full spectrum? Do plants need green? What are high-intensity discharge? Would a 2 40 watts T8 cool tubes be sufficient? Or do I need cool and warm or full spectrum tubes? I understand I need to run for at least 14 hours to imitate the sunlight. I plan to start with a 4foot shelf where I will grow seeds: mainly vegetables (tomato seeds is a fave) and herbs. Could you please help with the right info so that I can purchase the most accurate hardware to create my own grow light garden? Thank you.


I have been starting seeds under grow lights for the last three years and find it very satisfying. Full spectrum is a term a term used to refer to light that covers the electromagnetic spectrum from infrared through ultraviolet; sunlight is considered full spectrum so a grow light that is full spectrum is one that most closely resembles natural sunlight/daylight. Unfortunately I don’t understand your question on whether plants need green. A high-intensity discharge or HID light is a type of light which provides more of its radiation as light as opposed to heat, when compared with florescent or incandescent light, and give more light with less electricity. I recommend that you use full spectrum 4’ T8 grow lights, which have coating on the inside of the bulbs which make them more similar to sunlight. Or you could consider 4’ high output T5 lights. T5 fluorescents are more energy efficient, produce less heat and produce more light. However, they do not use the same ballast as T8 or T12 tubes and therefore not interchangeable, and are more expensive.

You should install the lights so that you can either raise or lower the light, or raise or lower the self, as you will want to maintain the distance between the lights and the plants as the plants grow. The amount of light/darkness will depend on the particular plant, as well as the intensity of light that you need will depend on the particular plant. However, both vegetables (including tomatoes) and most herbs grow best in full sunlight and therefore will need high light levels. I suggest that you puts your lights on a timer, which is more convenient that having to remember to turn them off/on each day. Personally I have used a 12 hours on/12 hours off cycle, with great success.