In order for plants to grow, they need four things:

• Light
• Water
• Heat
• Nutrients

Heat lamps provide two of the four crucial ingredients, making them an important part of your seed-starting operation! The truth is that seedlings need adequate light to grow. Full-grown plants don’t need as much light, but without 14 to 16 hours of illumination, the seedlings won’t grow healthy and strong. Seedlings without enough sunlight tend to be weak and look very spindly. But if the sun isn’t out for that many hours a day, what can you do? That’s where seed-starting lights come into play!

Starting seeds under lights is the way to be certain that your young plants and seedlings get all the “sunlight” they need to grow. Even if you start your plants on a windowsill, oftentimes they still won’t get enough sunlight. But with heat lamps, you provide both the light and the heat your plants need to grow. You’ll speed up the growth and encourage healthy, strong plants.

If you’re going to use lights for starting seeds, here’s what you need to know:

• 14 hours a day is the right amount of light. No less! You can go up to 16 hours per day if you want to encourage faster growth, but make sure the light isn’t so hot that you cause the seedlings to wither or dry out the soil. Use a grow-light system for the best results.
• Keep the lights clean. The grow-light bulbs (long tubes) tend to get dusty, and that can reduce the quality and amount of light shining on your plants. Clean them regularly!
• Rotate the seedlings. The light bulbs produce the most amount of light at the center of the bulbs and the least at the ends. For this reason, you want to rotate the seedlings. Place the seedlings at the ends of the bulbs into the middle every couple of days, ensuring that the amount of light received by all the plants is equal.
• Reflect the light. To double the effectiveness of the grow-light system, install aluminum foil or mirrors to reflect the light back onto the plants. It will help to increase the amount of light absorbed by the plants and soil, leading to faster growth!

An excerpt from “Essential Seed Starting Equipment“, courtesy of  Epic Gardening.