Grow Lights For Seedlings: When To Put Seedlings Under Light & How Much

Most homes don’t have enough natural lighting for seedlings, and trying to grow seeds on a sunny windowsill only results in disappointment and wasted time (and money!). But don’t worry, you don’t have to spend hundreds of dollars on fancy a grow lights for seedlings. I’m going to make this super easy for you!

One of the biggest frustrations new gardeners face starting seeds indoors is when seedlings grow spindly and weak. The only way to prevent leggy seedlings is to use grow lights.

But some new gardeners shy away from buying grow lights because they’re worried about the cost. And trust me, you definitely could spend a lot of money on plant grow lights.

A LOT of money!

But, for the average person, it probably doesn’t make sense to spend hundreds or thousands of dollars on fancy grow light systems for seedlings.

Don’t worry, you don’t need to spend a fortune! There are tons of options for different seedling grow lights out there, and it’s easy to find an affordable system that works for you and your home.

Related Post: How To Care For Seedlings: The Ultimate Guide

Starting Seeds Indoors Under Lights

If you are planning to get into starting seeds indoors, then you’ll definitely need some kind of a set up. It make things much easier (and a lot less cluttered) when you have a dedicated space for growing seeds.

This can be anything from putting your seed trays on the floor in the corner of the basement and hanging the lights overhead, or it can be a much fancier grow light system that you can buy or make yourself.

My grow light systems for seedlings

I have a great setup that fits perfectly in my spare bedroom. I bought a mini indoor greenhouse to hold all of my seedling trays.

It has a plastic cover that I can close all the way which is great for adding humidity around the seedlings.

I have lights that fit in there too, one hanging from the bottom of each shelf for the seedlings underneath (the lights aren’t in this photo though).

You certainly don’t have to get an indoor greenhouse like mine, you can use any type of seed starting rack that you want.

I sometimes use our extra garage shelves to add more space for growing my seeds, or your could buy a simple wire shelving unit if you want something more sleek looking.

If you want to start small, you can just buy a simple seed starting kit that come with a grow light and put it on a bookshelf or table (you could use either seed starting cells or peat pellets in this seed tray).

Related Post: Seed Starting Peat Pellets Vs. Soil: Which Should You Use And Why?

Why Use Grow Lights For Seedlings?

The first few years I tried growing plants from seed, I didn’t use grow lights. I am lucky enough to have a nice large south facing window in the spare bedroom, so I just set up a few shelves right in front of those windows.

This worked ok, but my seedlings were always thin and weak looking compared to the seedlings I saw for sale at the garden center.

Growing seeds near a sunny window

Things got worse for me once I started to experiment with different types of seeds, and it quickly became clear that my sunny window wasn’t going to be good enough (or big enough!).

In those early years, my seedlings were always weak and leggy, and many of them would just grow tall and flop over.

I discovered the hard way that seedlings never recover from this, and the plants don’t grow well in the garden either. I realized I was wasting a lot of time and money (and heartache) just to save a few bucks on grow lights.

Using seed starting grow lights prevents leggy seedlings

Benefits Of Using Grow Lights

That’s when I decided it was time to buy myself some grow lights, and I was amazed at what a difference it made!

Not only did my seedlings look fantastic, but adding a few grow lights meant I didn’t need to grow as many seeds because my seedlings were much healthier and stronger.

With proper seedling lighting, their survival rate was much higher, so I didn’t have to plant extra seeds to make up for that like I did in the past.

My grow lights definitely paid for themselves pretty quickly (since there was much less waste of seeds and dirt… and my time), and they continue to pay for themselves over the years.

Not to mention using lighting for seedlings have made my life much easier, and taken the frustration out of growing seeds.

Seedlings reaching for light

Benefit 1: Strong, Healthy Seedlings

The main benefit of using grow lights for seedlings is that your seedlings will be much stronger and stay more compact when they get enough light.

Proper seedling lighting is the the only thing that will prevent leggy seedlings, and thick, strong seedlings have a much better chance of surviving the transition to the garden in the spring.

Seedlings growing straight and thick under home grow lights

Benefit 2: Grow Your Seeds Anywhere In The House

Another benefit of using lighting for seedlings is that you can grow your seedlings anywhere in the house, you don’t need to worry about keeping them in a room that gets natural light.

This is a huge benefit for many gardeners, since most people don’t have huge sunny windows to grow seedlings in.

Plus you can hide your ugly seed starting setup away in a back bedroom, in the basement, or even in a dark closet if that’s the only space you have.

Without grow lights, it would be impossible for many people to start seeds indoors.

Do You Really Need Indoor Seed Starting Lights?

In order to grow strong, healthy plants, it’s super important to have the proper lighting for seedlings.

That being said, you don’t absolutely need indoor seed starting lights if you have a sunny windowsill, porch, or another super sunny space for growing seedlings.

I’ve started lots of different types of seeds in my sunny spare bedroom, and they survived just fine (though they were always leggy).

But if you ask me if the expense of buying a grow light is worth if for starting seeds. I’d say yes, absolutely!

Seedlings not getting enough light

If you’re just starting out and don’t want to invest a ton of money until you know you like it, then go ahead and try growing your seeds in a sunny window.

Just make sure it’s a south facing window, and the seedlings are as close to the window as possible. It never hurts to experiment and see what works for you, in your home.

But once you have a few seed trays going, and you know you’re hooked on seed starting, then I would definitely invest in proper lighting for seedlings.

How To Choose The Best Indoor Lighting For Seedlings

I mean… lights are lights, right? Nope! (but you probably knew it couldn’t be that easy) It’s very important to make sure you get the right type of lighting for seedlings, and all light bulbs are NOT created equal.

Just go to the hardware store and you know that now more than ever there are tons of different types of light bulbs to choose from.

Don’t worry, I’m not going to get super techie on you here (there’s enough technical information out on the internet already).

But it is important to understand that some bulbs (like regular incandescent light bulbs) are way too hot, and will only end up frying your seedlings.

Seedling lighting fluorescent bulbs

So what type of grow lights should you buy then? That’s easy! Your first option is to buy lights that are specifically made for growing plants indoors (plant grow lights).

You can find plant grow lights for sale anywhere these days, or you can buy grow bulbs and put them into a fixture of your choice (plant grow light bulbs come in standard sizes that are made to fit into any light fixture).

Another great option is just use standard cool-white fluorescent bulbs instead of plant grow lights.

When I went shopping for my very first set of seedling grow lights, I made my own using a standard shop light and fluorescent light bulbs. Here’s how I made my own grow light…

DIY Seed Starting Grow Lights

I’m always looking for ways to cut costs when it comes to gardening, so you can be sure my DIY seed starting grow lights are the most inexpensive option I could find.

This is a great option for beginners, and the supplies you need are readily available at any hardware store. Plus, you can swap out the bulbs and use the shop lights in your garage when they’re not being used for seed starting!

Supplies Needed:

• 1 four foot (48″) shop light fixture
• 2 four foot fluorescent light bulbs
• 2 small chains (something like this one)
• 4 S hooks (similar to these)

Starting seeds indoors under lights

There’s no special assembly required for your DIY grow light, simply pop the fluorescent bulbs into the shop light fixture, and you’re ready to go.

Depending on the type of shop light fixture you buy, yours may or may not come with chains. But either way, there should be holes in the top of the light to put an S hook through in order to hang the light.

I like using small chains and S hooks to hang my grow lights because they make it super easy to adjust the height of the lights as the seedlings grow.

Use two of the S hooks to attach the chain to the light, and then use the other two S hooks at the ends of the chains for hanging the lights from your shelf.

If you want something nicer and easier to use than chains and S hooks, you can get a adjustable grow light rope hanger to use instead.

Using chain to hang grow light for seedlings

You can fit two standard sized seed trays end-to-end under one 48″ shop light, or four of them side-by-side (just make sure to rotate your seedlings on a regular basis so they all grow evenly).

If you don’t want to mess around with buying all the parts to assemble your own DIY grow lights for seedlings, or you’re not sure how to hang it, then I’d recommend getting a grow light system like this one. That’s a great option, and it makes setting everything up a snap!

Lighting For Seedlings FAQs

Whenever I talk about lighting for seedlings, or show off photos of my DIY grow lights, I get a lot of questions about them.

I already showed you how I made them above (FAQ #1), now I’ll answer a few of the other frequently asked questions I get about how to use grow lights for seedlings (ask your questions in the comments below the post if yours isn’t answered here)…

Seed starter grow light hanging from shelf

When Do I Put My Seedlings Under Light?

The answer to this one is simple. Your grow lights should be turned on (or your seedlings should be put under lights) as soon as the first seed starts to sprout.

Many types of seedlings grow super fast, and they will start reaching for the light as soon as they emerge. So give them plenty of light right from the start.

Put seedlings under light when seeds start to grow

How Far Should My Lights Be From My Seedlings?

Keep your grow lights 2-3″ above the top of your seedlings at all times. At first, your light will sit directly above (but not touching) the plastic lid on the seed tray.

Once the seedlings start to grow, and you take the lid off, then you’ll have to adjust the lights on a regular basis so it stays above the top of the seedlings (having a grow light system that is simple to adjust make this job a whole lot easier!).

Your seedlings should never touch the bulbs, so make sure to check on them often.

Rotate the seed trays daily if you notice the seedlings that aren’t directly under the light are reaching for light, or aren’t growing as well as the ones that are directly under the light.

Using indoor fluorescent grow lights for seedlings

How Long Should I Leave The Lights On During The Day?

Your grow lights need to be kept on for about 14-16 hours a day. Don’t leave them on 24 hours a day though. Like us, seedlings need to rest for a few hours each day.

So plan to give your seedlings 14-16 hours of light during the day, and then leave the light turned off overnight. Use an outlet timer to make keeping this schedule a snap, and ensure your seedlings get the perfect amount of light.

Seedlings grown under indoor seed starting lights

In order to grow strong, healthy plants, it’s super important to provide the proper lighting for seedlings right from the start.

Light is a key part of seedling health, and it will give them a good start to life. Plus you’ll find that it makes your job much easier in the long run. Weak, leggy seedlings are delicate and much more difficult to take care of than healthy seedlings.

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.

Otherwise, if you just need a refresher, or you want a quick-start guide to growing seeds indoors, then my Starting Seeds Indoors eBook is just what you need.

More Posts About Starting Seeds Indoors

• Tips For Starting Seeds Indoors For Beginners
• Seed Planting Schedule: When To Start Garden Seeds Indoors
• How To Make Your Own DIY Seed Starting Mix (with recipe!)
• How To Fix Common Seedling Problems

Do you use grow lights for seedlings? Share your tips about lighting for seedlings in the comments below.

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