Tomatoes are long-day plants. Natural sunlight is considered the best for seedlings; however, there is usually not enough light in the shorter spring days for the needed 14–16 hours of combined direct and indirect light recommended for good growth.
There are several different types of grow lights available.
- Full-spectrum fluorescent bulbs can come close to replicating natural sunlight and are the most cost-efficient.
- High-intensity discharge lights come in several types and are more expensive, but they do provide an excellent supplement for natural sunlight.
- Metal halide (MH) bulbs give off a light toward the blue spectrum, prompting more leaf production.
- High pressure sodium (HPS) bulbs promote flowering and leggy growth from its red/orange spectrum, but it’s not recommended for use with tomato seedlings unless combined with other types of light.
- LED lights are now finding their way into the gardening world, but not all LED lights are suitable for growing. These are more expensive but last much longer and, more importantly, are much cooler than the other options, with less watering as a benefit. A 180-watt LED will easily compete with a 360-watt high-intensity discharge (HID), for example. We suggest you research advanced LED grow lights if this is the direction you choose to go.