Most homes do not have or receive adequate light for growing seedlings indoors. Even the most sunny windowsill is usually not enough to produce strong and healthy starts. Lighting is a vital part in The Basics to Starting Seeds Indoors, so we must then look to artificial lighting for options.
I briefly discuss grow lights in A Guide to Caring for Indoor Seedlings, but we’re going to take a look at all the details about them here.
Learn all the details about grow lights. Are they necessary for indoor seed starts, benefits to using them, how often to turn them on, which light to purchase, and much more! Everything you need to know about grow lights is right here! I’ve also listed more helpful gardening tips about indoor seedlings at the very end of this blog post.
Why Are Grow Lights Needed?
Many people have to supplement with another source of light by using a grow light. Even large, south-facing windows struggle to supply enough light to make seedlings strong.
Winters here in Missouri are usually very overcast. A day may begin in sunshine, but full sunny days are pretty rare until May arrives. This means that even if I place my seedlings in the ideal window, the light is too diffused my clouds to make an impact.
I didn’t use a grow light during my first two years of starting seeds indoors and the result was seedlings that looks thin and weak. These seedlings did terribly once it was time to transplant to the garden.
The next year I supplemented with a grow light and the difference was incredible! Sitting under a direct source of light for 14-16 hours each day produced seedlings that looked healthy, strong, and bright green!
So, do seedlings really need a grow light? My answer is yes. I’ve tried both methods and experienced much more success when using a grow light. The investment is worth it for my situation based on where I live, but feel free to experiment and test which option is best for you!
Benefits of Using Grow Lights
- Better Survival Rate: I experienced a huge increase in seedling survival rate after using a grow light vs only relying on natural sunshine. This means less wasted money, time, and effort!
- Stronger and Healthier Seedlings: I guarantee that your seedlings will come out much stronger, healthier, and colorful under a grow light. They’ll be much more prepared for transplanting too!
- Easier Management: Before using a grow light, I would have to rotate my seedlings at different times of day to ensure they were all getting a similar amount of light as the sunshine moved. A grow light can be placed on a timer so that it turns on and shuts off at the same times each day. They’ll still need daily check-ups, but no rotation needed!
- Grow Them Anywhere in the House: This is super important for me because we have a toddler and a baby on the way. Meaning that my seedlings would be destroyed in no time if I had to use the south-facing window in our house (in the main living space). A grow light allows me to have my entire set-up in a room safe from baby hands.
What Kind of Light to Use
There are a few different lighting options when it comes to grow lights. Please note that all bulbs are not created equal, and certain ones will lead to more success than others! Let’s break it down into the best and worst bulb options.
- Incandescents: these simply get way too hot for the seedlings to handle. You’ll fry the little guys in a very short amount of time!
- Full spectrum LED light: this is what most anything labeled as “plant grow light” will contain. These grow lights typically come with hanging systems and are easier to manage than shop lights.
- A florescent grow light: shop lights contain these bulbs and are a great and cost-effective option! You will have to create a hanging system for these bulbs, so keep that in mind!
How Much Light do Seedlings Need?
Seedlings need 14-16 hours of light every day. Make sure you don’t leave them exposed to the light for 24 hours a day. They need rest from the light just like they would get in natural conditions.
I recommend keeping your grow light on a timer so that it turns on and off at the same times each day. This is handy if you’re forgetful like I am or if you’ll be gone overnight!
How to Use a Grow Light
When to Put the Seedlings Under the Grow Light
Seed trays do not need to be under light until the first seedling begins to emerge. This is when the light becomes vital to their health!
Certain types of seedlings grow at a very rapid pace and begin reaching for the light as soon as they emerge. Give them plenty of light from the very start!
Distance From the Light
Grow light options are either full spectrum LED lights or florescent shop lights. Either one will work, but you will have to place them at a different distances from the seedlings.
- Full spectrum LED light: keep this light 2-3 inches above the tops of the seedlings. Be sure to adjust the distance from the light as your plants grow taller. This is the grow light we are using.
- A florescent grow light: this light will get hotter than an LED, so don’t place your seedlings quite as close. They will bake! Keep the light 16-30 inches from the tops of the seedlings. Adjust the distance as the plants grow taller.
Make sure that the leaves never touch the light as they can burn. Rotate trays if you notice any of the seedlings located on the edges are reaching or not growing as well as others. This can happen to the starts that aren’t directly under the light, so be sure to give them that needed time as well.
When to Stop Using a Grow Light
You’ll want to use a grow light on your seedlings until they are ready for transplanting to the garden.
The process of Hardening Off will begin exposing them to the great outdoors (sunshine, wind, and other elements), so turn the light off when they are outside. Put them under the light for another few hours once you bring them back inside for the evening.
Questions About Grow Lights
Do Seedlings Need 24 Hours Under the Grow Light?
No! They need rest at night just like any other plant located outdoors. Exposing them to too much light will only create shock when they move outside and experience night for the first time!
Give them 14-16 hours under the light and turn it off at night.
Should The Seedlings be Rotated Under the Light?
In the ideal situation, you should not ned to rotate the seedlings under a grow light. Sometimes, however, grow trays are wider than the light source, so the seedlings around the edge of the tray may begin to reach more than the ones directly under the light.
If this happens to your seedlings, simply rotate them each day to ensure that they all get an equal amount of time directly under the light.
Can you Start Seeds Indoors without a Grow Light?
Yes, you can! Grow lights are not a complete make-it or break-it item, but they do produce much healthier starts!
However, if you cannot attain a grow light or simply want to experiment with natural light first, place the trays in your sunniest window (usually south-facing).
More on Gardening
- The Basics to Starting Seeds Indoors
- 5 Tips for Transplanting Seedlings to the Garden
- A Guide to Caring for Indoor Seedlings
- How to Harden Off Seedlings