Lighting for seedlings can be a complicated and intimidating topic, but it doesn’t have to be. Once you learn about when and how to use them, you’ll find that it’s much easier than you think.
Don’t worry, I’m not going to get super technical on you here, I want to make this very easy. Below I will break it all down so you don’t get overwhelmed.
In this post, you’ll learn everything you need to know about using grow lights for seedlings. Including whether or not you need them, the best types to use, when to turn them on and for how long, how set them on an automated schedule, and much more.
Why Use Artificial Light For Seedlings?
Adequate lighting is a key part of successful seedling care, and it will help give them a good start to life. When they don’t get enough, they become tall, weak, and leggy, and may not survive for very long.
I’ve been growing seeds indoors for well over 20 years, and I’ve learned why this is so important from trial and error.
My Story
I didn’t use grow lights on my seedlings for the first few years because I have a large south-facing window in my spare bedroom. I set up shelves right in front of it, and that worked ok. But my seedlings were always thin and looked unhealthy compared to the ones I saw at the store.
Things got worse for me once I started to experiment with different types of seeds, and some would stretch so far towards the window that I had no choice but to toss them out.
That’s when I realized I was wasting a lot of time and money (and heartache) just to save a few bucks. So I decided to buy myself some grow lights, and I was amazed at what a difference it made. I was sold!
Not only did my seedlings look fantastic, but supplementing with artificial lights meant I didn’t need to plant as many seeds. That’s because they were much healthier and stronger, I never had to throw any of them into the trash again.
Do Seedlings Need Grow Lights?
The short answer to this questions is yes. Seedlings need artificial light indoors to grow as strong and healthy as possible, and it’s important to provide it right from the start. That being said, you don’t absolutely need to buy them.
If you’re a beginner, and you don’t want to invest the money up front, you can use a sunny window. Or better yet, if your home has a porch, patio, or another space that’s filled with natural sunlight, then try that and see how well it works for you.
But once you have a few flats going, and you know you’re in it for the long haul, I definitely recommend investing in proper lighting for your seedlings. They’ll end up paying for themselves in a short time.
Benefits
There are tons of benefits to using the proper lighting for seedlings. Below I’ve listed the main ones, so you can see why it’s so important:
- Stronger and healthier seedlings – The main benefit of using artificial lights is that your seedlings will be much stronger, healthier, and stay more compact than they would in a sunny window.
- Better survival rate – Once you provide enough light, you’ll find that the survival rate of your seedlings is much higher, and you’ll be so much happier with the outcome.
- Less waste – Since you won’t have to plant extras to make up for those losses, there will be much less waste. You won’t waste any seeds or dirt… or your time. Because of this, you’ll find the lights will pay for themselves pretty quickly.
- Much easier – Getting them on an automated schedule will make your life so much easier too. By using a timer, you can just set it and forget it, rather than having to constantly monitor and rotate your trays.
- Prevents legginess – Providing adequate lighting is the only way to prevent seedlings from getting tall and leggy.
- Grow seeds anywhere in your house – Since you won’t have to worry about keeping them in a room that gets tons of natural sunlight, you can grow your seedlings anywhere in the house.
Best Grow Lights For Seedlings
It’s very important to make sure that you use the right kind of grow lights for your seedlings. Some types, like regular incandescents, for example, are way too hot, and will only end up frying the tiny starts. Here are the best ones to use:
- Plant grow bulbs – Your first option, which also tends to be the cheapest, is to buy plant grow bulbs. You can find them for sale just about anywhere these days. They come in standard sizes that are made to fit into any fixture that you already have.
- Fluorescents – Another great option is to use standard cool-white fluorescent bulbs. I made my own seedling grow lights using a standard shop fixture and fluorescent bulbs. Get the step by step instructions here.
- LED grow lights – If you don’t want to mess around with assembling your own, or you’re not sure how or where to hang them, then I recommend getting a full system like this 4′ LED setup. Or something smaller like this one that’s 2′ long.
- T5 grow lights – Another great option is T5 grow lights. Here’s a 2′ long one that I recommend, otherwise that same one also comes in an 18″ length if you need something longer.
How Much Light Do Seedlings Need?
Understanding how much light seedlings require is just as important as choosing the right bulbs. So in this section, I’ll tell you exactly how many hours they need, and give you examples of the best schedule to keep them on.
Number Of Hours
Seedlings need 12-16 hours of light every single day, without fail. The reason this is a broad range is that some types need more than others do.
If you’re new to this, I recommend you start by keeping them on for 14 hours a day. Then monitor your seedlings closely. If they start getting tall, stretching, or growing sideways, bump it up to 16 hours per day.
On the other hand, if they are staying compact and thick, then you can turn it down to 12 hours to save some energy, and see how well they do with less light.
Best Lighting Schedule To Use
It’s important to stick to a strict schedule – consistency is important for uniform growth. So I highly recommend using an inexpensive outlet timer to keep it the same every day.
Some people like to follow a 12/12 lighting cycle for their seedlings. That means the bulbs stay on for 12 hours during the day, and they are off for 12 hours at night.
But in my experience, that’s not long enough, so I prefer running mine for 14-16 hours daily. I set my timer on a schedule to turn them on at 6:00am every morning, and to turn them off at 10:00pm each night.
If for some reason that doesn’t work for you, you could do a 7am to 9pm schedule, or something similar. The exact times don’t matter so much, as long as the schedule stays the same.
When Do I Put My Seedlings Under Light?
You should put your seedlings under light as soon as the first one germinates (starts to sprout). They grow very fast, and will begin stretching right away – even as they’re still emerging.
It’s important to note that some types of seeds need light to germinate. So, if that’s the case with any of yours, then you should put them under there right after you plant them.
Related Post: How To Fix Common Seedling Problems
How High To Hang The Lights
To be effective, the grow lights need to be fairly close to your seedlings. You should keep them 2-3″ above the tops of the leaves at all times. If yours have an adjustable intensity setting, you can turn that up and move the fixture higher (6-12″ above, depending on how strong the intensity is).
You’ll need to adjust the height on a regular basis as your starts get taller. The leaves should never touch the bulbs, or they could burn.
So make sure to check on them every day, and move the lights up as necessary. Using an adjustable hanger will make this job a whole lot easier.
If you need them for germination, or the lids are still on your trays, then hang them directly above (but never touching) the plastic.
When To Turn Off Your Grow Lights
As long as your seedlings are indoors, they should be under the grow lights. The only time you should remove them or turn them off is when you put your seedlings outside.
Once you begin to harden your seedlings, you can turn off the lights while they are outdoors. But, you should always put them back right away whenever you bring them inside, or they will quickly start getting leggy.
FAQs
No, and you should not put seedlings under grow lights for 24 hours a day. It’s important to follow the normal pattern of the sun, or your seedlings will suffer when it’s time to move them outside. Just like us, they need darkness at night to rest. So keep them on during the day, and turn them off at night.
If you provide the proper lighting for seedlings, then you should not need to rotate them. However, many times the trays are wider than the lamp fixture. So, you may notice some of the ones around the outside edges will start reaching. In that case, it’s best to rotate them daily to ensure even growth.
Yes, you certainly could try starting your seeds indoors without grow lights. However, most homes do not get enough sun for healthy seedling development. So, for the best results, I recommend supplementing with artificial ones.
Some types of seeds do need light to germinate, but others do not. Always check the packet for details, or research the specific varieties before planting them.
Adequate lighting is extremely important for success with seedlings, and it will give them a healthy start to life. Plus you’ll find that it makes your job much easier, with less waste and frustration.
If you’re new to starting seeds, and you want to learn everything you need know in order grow your garden from seed, then you should enroll in my Online Seed Starting Course. This self-paced course will walk you through it all, step by step. Enroll and get started right now!
Otherwise, if you just need a refresher, or you want a quick-start guide, then my Starting Seeds Indoors eBook is just what you need.
More Posts About Seedlings
Share your tips about using artificial lighting for seedlings in the comments below.
Rusty says
Thanks for all the Great information.
So I am using LED grow lights to start my seedlings. Some shelf racks have one light and some two. Which seedlings would benefit from being on the higher lighted shelves ?
Thank you for your time and assistance !
Amy Andrychowicz says
The seedlings that grow the fastest would benefit from being on the higher lighted shelves. If any of the ones getting lower light start to become too tall or are reaching for the light, then move those up. Check on them daily and rotate as necessary.
Tyler Wachna says
We started our seedlings inside a little earlier this year, and they are thriving, but we don’t plan to plant outside for another 1-1.5 months and they are out of space in the greenhouse shelves we are using. I was thinking of moving to larger shelves, but then we will lose the greenhouse covers that keep their growing space warm and moist… Any tips? Tomatoes and Peppers, now 8-12″ tall…
Amy Andrychowicz says
I would start hardening them off to get them ready to move outside. 1-1.5 months is the perfect amount of time to do that. Here’s how to harden your seedlings.
Warren Shore says
Do you know how to bypass the timer on the grow lights? My grow lights only go to 12 hours and I want to use a mechanical timer to get 16 hours of light
TIA…Warren Shore
Amy Andrychowicz says
Sorry but I’m not sure how you could by pass the built in timer on your lights. You might either need to get a different type of grow lights, or just manually turn them back once the 12 hour timer runs out.
Steve Stansbury says
Amy, we live in the mountains near Boone, NC at about 3800′. It can get pretty cool in April. Do you recommend using one of those heating pads underneath the containers along with a light? We’re hoping to start perennials. We are also starting some dahlia tubers at the same time. Thanks.
Amy Andrychowicz says
Yes, adding bottom heat will help to increase the success rate and speed up germination. Good luck with starting your seeds!
Heidi Nagy says
What I am confused about is the concept of blue, red, and clear light. I have noticed that you used clear/bright light bulbs.
Amy Andrychowicz says
To make it easy, just look for either a plant grow light bulb or a “full spectrum” one (which will include both red and blue light, both of which are important for plant/seedling growth).
Naomi says
What if you are growing seedlings for a partly shaded area? Would you still provide full light for the 16 hours? And then slowly wean it down once they are strong enough…?
Amy Andrychowicz says
Yes because the natural sunlight outside, even in the partial shade, is much stronger than it is indoors. Having the lights on your seedlings will ensure they grow strong and healthy, and don’t get tall and spindly. And, even though the seedlings are for partial shade, you’ll still need to harden them off when you move them outdoors, to prevent sunburn.
Cecelia says
What kind of soil do you use? I planted salad almost 2 months ago and my seedlings are not even 1/2” tall. My ph is good and seeds to because it’s the same with the mache.
Amy Andrychowicz says
I usually make my own, here’s the article with my recipe and tips for the best type of soil to use. The fact that your seedlings aren’t growing could be caused by a few things, including lack of light, heat, water…etc. This post will help you troubleshoot and figure out how to fix the problem.
Cindy Kruger says
Thanks fo the great information. Do you know the difference between the two light colours on my grow light. There are 2 switches, one red and one blue. Do I turn both on for seedlings?
Amy Andrychowicz says
Sorry, but I’m not familiar with those switches. If you no longer have the box, then I would look up your specific type of seedling grow lights to see if you can find instructions online.
Clayton Pearson says
Hi Cindy,
The blue lights are for the lower end of the spectrum (the seed starting and growth stages). The red lights are for the upper end of the spectrum (the bloom and fruiting stages). In my experience, if you use both on seedlings you may get really dark green plants, but they may develop more slowly.
Andrea Bauchan says
What room temperature is required to start seedlings under grow lights. I grow all my vegetable plants in my lower level which is colder than the upper level.
Amy Andrychowicz says
Most types like it warm in order to germinate and thrive. The grow lights will help a little bit. But if it’s below 65°F in your room, then try keeping your seedlings warm using a space heater or a heat mat.
Nicole says
Do I need to increase the frequency of watering when using grow lights?
Amy Andrychowicz says
The lights alone shouldn’t dry out the soil any faster. But once you remove the lids and add ventilation, then you will defiantly need to monitor your seedlings closely and water them more often.
Sue says
I just purchased a LED grow lite. It can be adjusted from 5-100%. I’m assuming that is intensity. Where should I set it for seedling? Larger plants?
Amy Andrychowicz says
Sorry but I’m not familiar with the specific settings on each type of LED grow light. 🙁 The box or instructions should tell you what each setting is best for seedlings, and also different types of plants.
Jared says
I am using a 630 watt led board sf7000 in a 3×3, PAR is ranging 350-420 temperature good, manual states 28 to 36” for seedlings, found that 6” above for germination till they pop then raising the light to 25” is a good height did have it at 16” an noticed new growth slightly discoloured Do you have any recommendations for light heights with this setup?
Amy Andrychowicz says
Sounds like a great light setup for your seedlings! I would definitely stick to the recommendations on the package and keep them between 28-36″. Start with 28″ when the seedlings are small, and move the lights up as the seedlings get taller. If they begin to get leggy, then move the light down a few inches. Sometimes you have to experiment a little in order to figure out the perfect height for the exact lights you’re using.
Laurie says
I just planted my germinated seeds. Do I need to go ahead and start using my grow light?
Amy Andrychowicz says
Yes, you should start using your grow light as soon as the seedlings have germinated.
Rick Bevan says
A friend of mine gave me some seeds from some experiment at the Univ of Florida.
She told me, that if I put ’em in a pot, and use a grow lite, It’ll work.
So I bought his desktop lite from amazon. It has 2 extensions coming out from it and they can be adjusted over the pots. Are these as effective as purchasing a bulb then putting in a fixture by the seedlings? I have no place to HANG an overhead, so will this suffice?
Thanks
Amy Andrychowicz says
I’m not familiar with the specific lights you’re talking about, so I can’t say for sure. But I would think that if they are specifically made for plants, then they would work… as long as the fixture is large enough so bulb will cover all of your seedlings.
Nancy Nowak says
Are T8, 32W 500K 48 inch bulbs ok for growing seedlings?
Amy Andrychowicz says
Yes, those light bulbs would be great to use for your seedlings!
Mike Murphy says
I purchased a grow light bulb to go into the ceiling socket. Is it a waste of time to have purchased it? It will be a few feet from the seedlings.
Comments and suggestions welcome!
Mike Murphy
Amy Andrychowicz says
Putting a grow light in the ceiling fixture won’t do anything for your seedlings. It is too far away, and will have no benefit. The light needs to be a few inches above them at all times in order to work.
Mike Murphy says
Thank you Amy….