Do I need full spectrum grow lights for seed starting and seedlings? (for any budget)

While not required, the short answer is that your seedlings will grow stronger and more compact with properly placed grow lights. And healthy seedlings mean higher yields and more to harvest.

But this does not mean you have to go out and spend lots of money on a top-of-the-line full-spectrum grow light panel.

Regardless of budget, I will give you a solution that will work. Impatient? Click here to jump to my three recommended approaches to grow lights at any budget.

Seedlings need light as soon as you see the first leaves
Seedlings need light from the moment they sprout
Please note: Having a full spectrum grow light panel is of course far superior to placing starter pots in a window sill. But both methods do work. The limiting factors are the lenght of your growing season and the result or yield you should expect. 

But before we get into which solution suits your needs and situation best, let’s spend a few minutes on why light is essential to seed starting and seedlings.

So what is all this talk about grow lights about?

When gardening outdoors, we get used to natural sunlight and days with more than 15 hours of daylight.

However, the natural light indoors is nowhere near enough to grow herbs, tomatoes, or hot peppers indoors during the dark times of the year.

Bhut Jolokia ghost pepper seedling grown under grow light
Grow lights help nurture vigorous seedlings.
Sure, you are fine if you place the pot on a sunny windowsill with direct sunlight during spring or summer. But come autumn and winter there is not enough hours of light to go around.

Seedlings want 14-16 hours of light daily. And 6-8 of these hours should be direct sunlight. The light is converted into energy that helps plants grow and develop. Yea, that’s right, photosynthesis – the process explaining how plants use sunlight, water, and carbon dioxide to create oxygen and energy.

But full spectrum grow lights are expensive

This is true. Full spectrum grow light panels can get expensive. Even worse, if you are an avid gardener, you may need more than one panel.

But it does not have to be all or nothing.

To put it simplistically, there are different colors or spectrums of light. And when you mix red, green, and blue light, you get a light that looks white to the human eye. And for me, a white grow light has worked perfectly fine for seed starting and seedlings.

I use both white spectrum and full spectrum grow lights. If you consult the engineering light experts, you will find that they recommend grow lights labeled either as a blue-green spectrum or a balanced light spectrum [1] for seed starting and seedlings. Blue spectum lights promote leaf growth and the red spectrum range promotes fruiting and flowering. Still, I have had great results using the less expensive white spectrum grow lights.

What about Watt, Lumen, and Kelvin

To keep this simple, you should focus on two main concepts.

Watt is important as it tells you how much electricity you will consume and pay for at the end of the day.

Lumen measures the amount of visible light that radiates from a light source. When I took my first course in hydroponics many years ago, I was told to look for a ratio of 100 Lumen per Watt. This has served me well, and finding inexpensive LED light sources has not been difficult.

The good news is that all this information can easily be found on the packaging or the bulb itself. Look for “L” or “lm” for Lumen, “K” for Kelvin, and “W” for Watt.

Information about Lumen, Kelvin and Watt is clearly printed on the bulb.
The yellow dots show 9,4 Watt (LED), 806 Lumen, and 2700 Kelvin on a regular lamp in our home.
Kelvin measures the color temperature or spectrum of the light - see the section above.  But as white spectrrum grow lights work well for seed starting and seedlings, I have decided to embrace the Kelvin reading it gives me. 

Remember, for seed starting and seedlings; you are not expecting flowers or fruiting. Mother nature will take care of this stage of development as we transplant or move the plants outdoors.

If you did expect flowering or fruiting indoors, it would change your needs dramatically. You would, for example, need a full spectrum light panel to grow tomatoes or peppers indoors during winter in zone 7. But for seed starting and seedlings, white grow lights have also worked well for me.

Grow lights make it possible to grow herbs and vegetables indoors year-round
Full spectrum grow lights allow us to eat homegrown lettuce mid-winter

3 approaches to grow lights

Start by asking yourself one question. Given my available budget, how can I best replicate 14-16 hours of sunlight?

Here are my 3 recommended approaches:

  1. Use the tried and tested window sill
  2. Use an existing LED lamp you already have
  3. Buy a purpose-built grow light

Let’s look at the pros and cons of each approach.

1: The classic window sill approach

The window sill approach is tried and tested, and I know firsthand that it works. But there are limitations.

Pros: It is the easiest and cheapest approach while making your house look nice as the seedlings develop.

Cons: The main challenges of the window sill approach is that you have a shorter growing season, most likely tall, spindly, and leggy seedlings, and a lower yield and harvest.

Conclusion: It works and is cheap, but there is a better way.

2: Use an existing LED lamp you already have

Use an existing LED light source or purchase a LED bulb for your light fixtures or lamps.

I recommend sticking to LED lights, as regular light bulbs generate too much heat. You want to place your light close to the seedlings.

Pros: Inexpensive. I look at it like this. I need light indoors. Why not use a light source that works for me and as a grow light for my seedlings? It’s a win-win.

You will find that your growing season is more prolonged and that seedlings grow more solid and compact.

Cons: There are two main challenges to using standard LED light bulbs. First, getting the light source close enough to your plants can be tricky. Also, you will lose a lot of light as regular light fixtures often are designed to “spread the light.”

Conclusion: Still, for me, this is the ideal budget solution.

3: Buy a purpose-built grow light

It is hard to argue against buying an inexpensive white spectrum grow light or even grow light panel. Your seedlings and plants will grow stronger and healthier, and it is essential to remember that it is an investment that will last you for years to come.

Pros: Provides the best possible environment for your seedlings. Grow lights are, by design, built to reflect the light on your seedlings.

Cons: It will cost you more than the other two approaches. Also, you will more likely than not place the grow light in a tucked-away space and thereby not benefit from the additional light source for your home.

Conclusion: If you have the budget, I doubt you will regret buying a white spectrum grow light. Seeing vigorous seedlings grow and develop is a great feeling.

Bonus: When to use and where to place the grow light

Start using your grow light when you see the first leaves sprouting or from day one for seeds needing light to germinate.

Place your grow lights as close as possible. And when I say close, I mean as close as 1 inch (3 centimeters) from the seedlings.

But do keep the following two factors in mind:

1. Your seedlings need airflow to stay healthy

You want airflow and proper air circulation for seedlings to grow strong and healthy. Do not create a box where the air is stagnant. You could be inviting all kinds of diseases and fungi.

2. Does your light source generate heat

Put your hand under the lamp to get a feel for the level of heat your light source generates. You do not want to burn or scorch your seedlings. This is especially important if you are using non-LED type lighting.

Now, do not touch the light source. Place your hand at a safe distance to get a sense of the generated heat.

You can place most LED lights close to the plants for maximum effect. But always check, as it can vary.

Useful sources:


Mattias Magnusson: Hello, I'm Mattias, a passionate and experienced gardening enthusiast. I am the creator of, your guide to year-round herb and veggie growing. Let's simplify green living, no matter your space or location.