A Beginner’s Guide to Indoor Grow Lights for Starting Seeds

This post​ has been updated to include ​an ​LED grow lights section ​and information on picking and using an indoor grow light.

​An indoor grow light is one of the best investments I’ve made as a gardener. When I first started out, I used whatever indoor sunlight I had at the time.

It wasn’t enough.

indoor grow light illustration

I would watch ​seedlings lean over dramatically, and​ they just never lasted long.

​Then, I used a household light that wasn’t designed for growing. That was a better option (given the low light levels), but the plants didn’t have a good color and just looked leggy and weak overall.

​I eventually ​purchased an indoor grow light to start my seeds, making growing veggies indoors much easier!

Grow lights can be really confusing as a beginner​! It’s easy to get lost in the details and deciding whether one kind of light is better than another.

I like to keep things simple.

To do that, I’m going to give you a brief ​​grow light rundown (any other fans of The Office? 😉).

​​Two of the most popular indoor light options are fluorescent grow lights and LED grow lights. ​

Advantages of Indoor Grow Lights

Using an indoor grow light ​really has its perks.

For example:

  • Y​ou can start​ your seeds indoors when it’s too cold out​side. ​​
  • You can make sure your seedlings get enough light each day. (Even in the outdoors, too much shad​e or cloudy days can keep them ​from getting the amount of sun they need.)
  • You can grow microgreens for indoor, year-round veggies​. This bypasses the need for great sunlight or that “sunny room in your home.” (Not everyone has this!)

Personally, I use grow lights to support seedlings until they go outside. I start all kinds of peppers, herbs and veggies i​ndoors.

indoor grow lights for pepper seedlings
Indoor Pepper Seedlings Under Grow Light

I also use light to grow microgreens, small leafy vegetables like lettuces and some herbs too. These stay inside all of the time and do really well.

Eventually, I may try growing pepper plants inside year round. I believe this is possible with the right grow lights, but I haven’t done this yet.

Do I Even Need A Grow Light?

​Great question! I’m not going to tell you to buy something if ​you don’t need it.

​Here’s my opinion…

If you want to ​grow plants that have low-to-medium-light needs, such as lettuce and microgreens, you can definitely give your natural light a shot. South-facing windows tend to provide the brightest, indirect light during the most hours of the day.

Just be sure to account for winter months when you’re not going to get as much sun.

growing microgreens
Tray of Microgreens

If you’re growing edibles that have high-light needs, such as peppers and tomatoes, I would definitely use an indoor grow light. They really do need that support.

T5 indoor grow light starting pepper seeds
T5 Grow Light Stand Above Pepper Seedlings

Some Grow Light Terminology

You’ll see a lot of metrics used when it comes to different grow lights. This section is just a brief overview (rundown 😉 ) of some of the main ones.

​A Kelvin (noted by K) is the color temperature of the light, and it lets you know how it compares to actual sunlight. 

For seedlings and encouraging vegetative growth, you’ll want to find a grow light ​​between 5,000 to 6,500 Kelvin​. (6,500 is ideal.) This is a blue color that produces daylight​.

kelvin color scale
Kelvin Color Scale

​Picking A Grow Light

Before you choose a type of grow light (more on that below), here are some things ​you’ll want to ​look out for.

Coverage Area
​Consider the size of your grow light because it needs to ​provide light to ​​all of your plants.​ ​Don’t place seedlings too far beyond the boundaries of the light​.

(If your seedlings look like they’re leaning, they’re probably too far away.)

leaning seedlings
Leaning Seedlings

Set Up
The grow light set up is ​dependent on what your growing space is like and how many plants you intend to grow. Here are some things to keep in mind before you choose a light.

  • Many grow lights hang, others come with an attached stand and some are just bulbs that you can screw into light fixture (like a clamp light). ​Pick whatever works best for your growing space.
T5 hanging indoor grow light for starting seeds
Hanging T5 Grow Light
  • Grow lights generally need to be 2 to 4 inches away from the tops of your plants. Some LED lights may need to be placed 12″ or higher. If you pick an LED, be sure to verify how far away it needs to be from your plants and that you have the space to accommodate this positioning.

​Shop Lights
Some say fluorescent lights, such as shop lights, are fine ​for growing seedlings. (I used to think so too.)

After I got my T5, I realized just how weak my ​plants were, and that it often affected their health when they went outside.

The issue is that regular fluorescents may ​not have the capability to support photosynthesis and growth in your plants. ​Just wanted to give you a heads up about this!

​Fluorescent Grow Light​s for Seedlings

​T​he compact fluorescent lamp (CFL) and T5 are two of the most common types of fluorescent grow lights​. ​

As it name implies, the CFL is compact an​d it has a distinct, twisty bulb. This is a great cost-effective option ​if you’re just starting out and aren’t growing a lot of plants.

CFL bulbs are generally easy to find online and in stores, and the setup is simple… just screw the bulb into a lamp.

cfl grow light bulb
CFL Grow Light Bulb

The T5, on the other hand, consists of long, vertical tubes that run parallel to each other​. These bulbs often come in lengths like 2 feet and 4 feet i​n a grow panel that you can hang.

Otherwise, you can purchase individual T5 tubes and put them in an existing shop fixture you’d like to use.

indoor grow lights growing peppers indoors

​Safety Note 
Fluorescent lights contain a small amount of mercury. This is cause for concern in the event that a bulb gets broken and then it emits mercury vapor, which is toxic to humans.

I’ve never broken a bulb, ​but it’s something to ​be aware of. ​(Shortly after I published this post, I did break a fluorescent bulb and it was scary!)

The United States Environmental Protection Agency (EPA) has a page that explains what to do if a mercury-containing bulb breaks.

Using LED Grow Lights for Seedlings

Light emitting diode (LED) is another popular light for indoor gardening, and it has some distinct advantages.

For one, they are mercury free. ​Energy efficiency is another perk because they produce more light for the same amount of electricity as compared to fluorescent.

They also have a longer lifespan and you won’t have to replace the bulbs as often.

LED grow light
Mars Hydro LED in Grow Tent

The main disadvantage of LED grow lights is that they tend to have ​​more of an upfront cost. Fortunately, more product offerings are coming on to the market and making them more affordable then they’ve been in the past.

Another thing to pay attention to is you want to place your LED light at the proper ​height.

I’ve seen some LED products that get spaced the usual 2″ to 4″ high, while others need to be at least 12″ high. It depends on the wattage of the light.

Be sure to follow the recommended height specifications so you don’t have any growth problems.

This HID section was part of the original grow light article. I’m leaving ​it in just in case y​ou find it interesting…

High Intensity Discharge (HID) Grow Lights

High Intensity Discharge (HID) lamps are the most expensive and advanced option when it comes to indoor growing. This is because the light discharge has an extremely high intensity and double the efficiency of a fluorescent grow light.

(As an example, it takes a fluorescent light 800 watts to generate as much output as one 400 watt HID lamp.)​

Two types of HIDs are the High Pressure Sodium (HPS) and Metal Halide (MH).

The MH emits a midday sun heat that helps plants develop leaves.

The HPS produces an early morning or late afternoon heat, which gives a more yellow to orange to red spectrum. This is effective for and helping peppers flower and produce fruit.

The HID is an ideal indoor grow light solution for a greenhouse or sun room. This provides you with a solution if you do not receive enough natural light in your location.

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Example Grow Light Setups for Indoor Plants

I thought it would be helpful to see​ some of these grow light products. There are many other options for setting up your indoor lighting.

These​ are just examples of some popular options ​to get you started.

​CFL Grow Light Example

The bulb screws into the light fixture, and then you can clamp it where you like. This is a cost effective option for smaller areas.

​T5 Fluorescent Grow Light Example

Covers a standard 10×20 grow tray. The optional ​rope hanger gives you a way to easily raise and lower your light.

​LED Grow Light Example (Amazon)

Mars Hydro TS1000 LED

Mars Hydro TS1000 150W LED

LED Strip Light Option

LED Strip Grow Light – 48″ (Bootstrap Farmer)

Can be daisy chained (up to 7 grow lights) and mounted vertically or horizontally for a custom growing environment.

Optional: Programmable Light Timer
A light timer automatically turns your grow lights on and off. I recommend keeping your lights on for 16 hours a day.

Here’s a timer that will do this for you so it’s one less thing you have to do each day. 🙂

Starting More Seedlings At A Time
So what happens if you want to start more seedlings than what your grow light covers?

You can ​get a 4 foot ​grow light ​to cover multiple trays. ​You can also get an adjustable shelving unit and then hang your preferred ​grow lights above each shelf. ​​

Another option is to get a done-for-you-setup. For example, this product from Gardener’s Supply Company​ has the shelving, grow lights and pulley system so you can customize the light height on each shelf. This option is convenient, but expensive!

» Related: More Recommended Plant Lights & Growing Supplies

​How To Use Indoor Grow Lights

Let’s make sure that your seedlings get the benefit of the grow light you’re using. Here’s how to do this…

Whe​n​ Should You Start Using Your Grow Light?

​​In many cases, you won’t use your grow light until your seeds have sprouted. Some plants like peppers and microgreens don’t need light to germinate. Others, such as lettuce and some flowers, do.

Check your seed packet to know for sure.

​How Far Should Seedlings Be from the Grow Light?

If you recall in this section, I mentioned that you want to make sure your plants are covered by the light. Leaning plants are a good indicator that they aren’t being covered sufficiently.

The height of the light should generally be between 2 to 4 inches away from your seedlings.

Some LED grow lights need to be 12″ or higher. Check the product information to be sure.

You want to end up with short and stocky plants.

(If you’re growing microgreens, these seedlings are usually anywhere between 1″ to 3″ when you harvest them.)

pepper seedlings in peat pots

​How Long Do the Grow Lights Stay On?

​Your indoor grow lights should stay on for about 16 hours each day.

You can make this process easier by getting a programmable light timer ​to turn the lamp on and off automatically. Set your light to turn on at sunrise and then turn off 16 hours later to give your plants that 8 hour rest.

Using Indoor Grow Lights to Start Your Seeds Comes Down To This

Ultimately, grow lights come down to your preferences, growing space and whatever your budget allows. Just start small if you’re not sure how ​often and how much you’d like to grow.

So I don’t know if Charles would have liked my version of a rundown because I’m like Jim Halpert and not exactly sure what this means. But, I do happen to know about The Office filming locations because, like I said, I’m a fan. 😀

Fortunately, I only care what you think. 😉 I sincerely hope this guide on growing lights helps you successfully grow your ​veggies indoors.

And, speaking of that … It really feels empowering to be able to grow your own food. Whether you can’t find what you need in stores or you just want to be more self-sufficient, this is an excellent step in that direction!

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Jenny is the creator of Grow Hot Peppers. She is a self-taught gardener and has been growing peppers and a plethora of veggies for over 10 years. When she’s not writing or gardening, she loves eating spicy foods, hiking, and going to the ocean.

10 thoughts on “A Beginner’s Guide to Indoor Grow Lights for Starting Seeds”

  1. I recently purchased $50 worth (because of shipping and handling) or seeds. Its been three weeks or so and I don’t see only one seedlings popping out? Should I be frustrated? I am since I it probably doesnot take this long for the first shoot to come out. Do they need fertilzer. I started with individual pots and had them in my garage for natural light. Any suggestions is helpful. Is there any money back guarantee?

    • Hi, thanks for your questions and sorry to hear about the trouble with the seeds. How long it takes the seeds to pop (germinate) is totally dependent on what kind of pepper you are growing. For example, a jalapeno will germinate much faster than an habanero or bhut jolokia. And no, you don’t need fertilizer right now. You also don’t need any light until the chillies actually emerge past the soil. As for a money back guarantee, that’s dependent on the seller’s policies. Contact your seed provider and see what he/she says.

      What is needed for chile pepper germination is the following:

      • Soil temperature around 80 degrees F. Use a heat mat under your pots, or place the containers on top of a warm area such as a computer monitor or refrigerator.
      • Plastic covering over the tops of your pots. Use plastic cling wrap to cover the containers and poke some holes in the top. This helps create a mini greenhouse environment and keeps the soil retain moisture. Be sure to remove this covering once the seedlings do emerge.
      • Make sure your pepper seeds are no more than 1/4 inch away from the top of the soil. Pepper seeds don’t have the energy to push past a thicker barrier. Correct this problem if needed.

      Those are bare essentials. Also, make sure you are using some kind of seed-starting mixture; do not use potting soil because this won’t work. And for future reference, you can always try soaking your seeds in water for 24 hours before you want to plant them. The soak helps weaken the seed wall and helps break its dormancy. Hope this helps!

  2. Hi I grow chilis evry year I love them. This year iv got some bhut jolokia and naga viper. Iv not yet managed to over winter a plant yet. I’m in the process of preparing what I need to do this. Iv purchased the fertiliser and I have some grow lamps 1 is a blue spectrum light and a red spectrum light. How many hours will I need to have the lamps on for and which of the bulbs will be the best for my chilis?

    • Hi Danny, sounds like you’re on the right track so far. I usually leave my grow light on for about 12 hours during the winter, but some people will leave the lights on for longer. Just watch your plants closely to see how they respond.

  3. 3000 Lumens is minimum to get growth.
    more than 10,000 Lumens and theres no difference anymore so 3000 to 10000 Lumens is good.

    • I’m an engineer, and part of my recent job duties involve analyzing failure modes in LED grow lights as well as design of LED grow lights.

      All LED grow lights are more efficient than HID lighting. Plus if designed properly, they have a very long life–each LED has a 50,000 mean time between failure. Proper design means that if one LED fails, the rest continue to operate normally. HID lights must be replaced often. By 10,000 hours, there can be a loss of up to 70% of the original level of visible light from the fixture.

      LED grow light manufacturers design lights that use as few as two LED colors (red and blue) to over 10 colors. I have seen claims of 13 different colors. Some manufacturers include white LEDs which put out a low level of light spread over parts of the spectrum that the other LEDs don’t cover. One of the reasons to do this is that plants do use a little in the green and yellow part of the spectrum. The plants can do well enough with the 2 color lights–especially if the use is vegetative, and the extra colors serve to speed up growth and improve some of the production characteristics. Nowadays, many of the more sophisticated lights include a UVB emitter and one or more infrared emitters, so it’s not all visible (to humans, anyway) spectrum being produced by these lights.

      At this point, the more sophisticated LED lights produce a spectral signature that very closely resembles the generic consumption curve for plants. On top of that, there are a few manufacturers that have tunable lights–they produce a spectrum that can be tweaked for particular plants, as well as tweaking for the flowering and fruit production stages. These lights are currently pretty pricey.

      If you’re willing to go with a fixed configuration, the lights that have 9 or more different spectra will give you a very good bang for the buck. And speaking of peppers, I have my pepper seedlings growing under such an array of lights, and they are doing quite well. I’m using 45 watt (though they actually pull around 40 watts) fixtures; they are positioned about 16″ above the plant trays to illuminate a 4 square foot area. (That’s about two 10 x 20 trays, which of course are really 11 x 21 inches!) Since I use 2-inch cells, that means one light is sufficient for 72 cells.

      I would expect a 64-watt flourescent light to illuminate an 8-square foot area. So how is this more efficient? I’d have to run the flourescent light for 16 hours per day to achieve the same results as I do with running the LED lights 9 hours per day. So over a day, 64 watts * 16 hours = 1024 watt-hours, whereas the LED lights for the same space require 80 watts * 9 hours = 720 watt-hours. It’s not quite the same, because the LED lights produce a darker green leaf in that amount of time, so I suspect that I could cut back to get the same results.

      The 45-watt LED lights are retailing for around $30 on Amazon. A basic 4-foot flourescent light with grow bulbs is not much cheaper. If you live in an area with expensive electricity, the break-even point with LED lights occurs during the first year. If you factor in maintenance and replacement costs, these lights are a financial win. However, I believe that the real reason to use them is because of the tailored light spectrum that is far superior to any other lighting system.

  4. I have two 400 watt HIDs with 6500k bulbs. I’m just beginning my aeroponic grow. I’m growing 18 hot peppers. I’m wondering if anyone knows how many watts 400 or 800 is sufficient for all of them to flourish?

  5. Hi I have about 5 poblano and jalapeno plants that have just started growing (we had a late start here in Oregon this year) and now we are under a freeze watch. I want to let them finish maturing and getting bigger until I harvest them. What is the ideal light for finishing off a chile pepper plant at this time of year? Many thanks!

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