“Is there a difference between grow lights and regular lights that you can mount under a cabinet? I started seeds with the latter and everything sprouted but isn’t growing.” Question from Jacqueline of Casa Grande, Arizona
Answer: Yes. There is a big difference between regular shop lights and grow lights. Grow light bulbs cover a fuller light spectrum closer to that of sunlight. Fuller-spectrum lights cover all or most light wavelengths, from infrared to near-ultraviolet, which plants need to gather energy. This is because plant chlorophyll gathers light at all visible wavelengths and beyond (view the chlorophyll wavelength chart by clicking here).
You can achieve a broader or fuller spectrum of light with fluorescent shop bulbs in several ways. The cheapest way is to use a balance of warm/red and cool/blue bulbs (bulb types are indicated on the packages). Together, a warm and cool bulb will cover much of the light spectrum, but not all. Some fluorescent bulbs are specially designed for plant growing and cover more of the spectrum–up to 94%.
In general, fluorescent bulbs are not very strong–meaning their light output is relatively low–so they must be placed just inches above plants for best light reception and growth. Otherwise, your plants might become leggy.
Black Gold Horticulturist