How to Choose a Grow Light

Specially designed light stands make it easy to provide the intensity of light that seedlings require.

WHEN starting seeds indoors, one of the most important factors is light. Sure, you'll want to choose a good seedstarting mix and establish a good watering routine, but proper lighting is crucial for healthy, stocky seedlings. The good news is that grow lights, when used correctly, can give seedlings all the light they need to thrive.

Here are the key points to consider when growing seedlings under lights:

Light Intensity

Seedlings require lots of bright light, and when they don't receive enough of it they get weak and leggy. In most cases, even the sunniest windowsill will not provide the intensity of light they need. The best solution is to grow your seedlings under specially designed LED or fluorescent grow lights.

Growing plants under lights lets you control light intensity in two ways: the brightness of the bulb and how close the bulb is to the plant's foliage. This means you can provide high light intensity by positioning the bulbs just 2-3″ above the foliage. LED grow lights are especially good for seed starting because they give off very little heat. They also use half the electricity, last 5x longer than fluorescent bulbs, are mercury-free, and won’t shatter like glass. Regular incandescent bulbs are not used for growing seedlings because they give off too much heat and can burn tender foliage.

As your seedlings grow, raise the light fixture about once a week to keep the lights a few inches above the foliage. A light stand with one or more adjustable fixtures makes this task easy.

Duration of Light

Most vegetables are "long-day" plants, which mean they require 14 to 18 hours of sunlight (or artificial light) each day. A rest period is equally important for healthy growth, so be sure your seedlings also get at least six hours of darkness. Using an automatic timer is the best way to ensure that the lights are on for the right amount of time each day.

Color of Light

Natural sunlight is the ideal light for starting seedlings, but with full-spectrum light bulbs, you can come pretty close. Both LED and fluorescent full-spectrum bulbs produce a balance of cool and warm light that replicates the natural solar spectrum.

To learn more about seedstarting, including tips for planning and timing, fertilizing, temperature and humidity, thinning and hardening off, read How to Start Seeds.