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Using a Grow Light to Start Seeds Indoors

Katy's garden of herbs, peppers and greens is constantly expanding as she learns new techniques and tries growing new plants!

Starting plants from seed is a great choice, but it's super hard without an LED or at least some form of grow light.

Starting plants from seed is a great choice, but it's super hard without an LED or at least some form of grow light.

Thinking about growing some herbs or veggies? Starting them from seed is a great choice but it's super hard without an LED or at least some form of grow light.

The natural light from a window is not going to cut it! Seedlings don't do well when in a window. Even the most hardy seedlings have to struggle. That's not what you want for starting out a garden.

Thankfully, adding a grow light is super easy. Read on to learn how to start your seeds out right under grow lights!

Do I Need a Grow Light for Germination?

Before you buy a light, you'll want to know if it's really necessary.

Let me tell you what all experienced gardeners know: seedlings are so hard to start indoors with natural light. Even with a sunny window, they only get partial light that you can't control.

Even if you got your seeds to sprout and they seemed healthy, they probably didn't grow to maturity. That is because they spent all their energy growing towards the sun instead of developing. They burnt themselves out before they could get started!

Using a grow light to start your plants inside takes so much guess work out of growing. Whether these sprouts will end up in the garden or stay inside forever, using a light will make all the difference.

Grow Light 101

Grow Light 101

LED Grow Lights for Seedlings

LEDs are a great option for grow lights. They are a bit more energy efficient than fluorescent and there are a lot of options out there. You'll find two main types: free-standing and traditional hanging.

Free Standing Lamp ($30-$40)

For a small area free-standing lamps are a good option. For my earlier years germinating seeds inside I got this Winjoy 30W Lamp. I'd recommend it for around 10-15 seedlings.

It keeps things on a small scale and affordable. You'll find this lamp is really handy because you can adjust the height of the lights as your seedlings grow.

Hanging LED Grow Light ($50-$100+)

If you want more than 20 seedlings, you'll need a classic grow light that hangs from the ceiling or a shelf. This Goldspark 600W light is very affordable and my plants have thrived under it. I use it indoors for peppers and tomatoes.

I didn't know until I got it that it has a switch that allows you to set the spectrum. So I could use just the blue light while the plants were young. Then I flip the switch to the Bloom setting once they're more mature to use the red spectrum.

No need to buy another light or swap them out!

How to Pick an LED Grow Light

The market is now flooded with LED lights. That's great for us as growers but how do we choose?

Here are some important considerations when selecting an LED light:

  • Must have Red and Blue spectrum.
  • Anything over 100W needs a cooling system.
  • Option to select Flower or Veg spectrum is helpful for seedlings.
Seedlings that you start indoors under grow lamps are more hardy when they reach maturity

Seedlings that you start indoors under grow lamps are more hardy when they reach maturity

Red vs Blue LED Spectrum for Seedlings

The spectrum that your grow lights emit is very important and it can get pretty technical. I'll give you the overview you'll need for growing seedlings and you can follow these links if you want to learn more.

You'll see that many LED grow lights emit in the red and blue spectrum. This is because plants evolved to use red and blue wavelengths most efficiently. You can actually control whether a plant uses its energy for growth or flowering by controlling the spectrum.

Blue Light for Veg/Growth

A plant exposed to blue light only will spend that energy on growing and building it's roots. This is called the Veg stage.

Veg is most important early in a plant's life. Blue light is thought to be good for seedlings. But if you keep an indoor plant under a blue LED for all of it's life it won't grow to its full potential. Learn more about what blue spectrum does to plants.

Red Light for Flowering

A plant that receives red light only will start to flower. Obviously, this is the Flowering stage.

When you want a plant to give fruit, this is the wavelength you should expose it to. For most vegetables and herbs you don't want much red light early in it's life cycle, if at all. When you're growing herbs indoors to use for cooking you don't want those to flower, so avoid a lot of red light.

Full Spectrum for Indoors Plants

Instead of just red or blue light, you will see some LEDs advertising "full spectrum". These lights will hit more of the visible light spectrum than just red and blue.

You'll want to consider an LED or fluorescent with a wider spectrum if your plants are staying inside. The fuller coverage of light will produce higher yields.

Other Considerations for Growing Sprouts

Light isn't the only ingredient to strong seedlings. You will also need to pay attention to the seed's water, temperature, humidity and nutrients.

Seedlings can benefit from some added nutrients but be sure to read on how to use fertilizer on seedlings before you start.

When Should I Add a Light to My Germinated Seeds?

Add a light as soon as any green part of the plant emerges. The new leaves need as much "sun" as they can get to give the plant energy. That means starting as soon as possible.

I turn my lights on as soon as I sow the seeds. The light doesn't matter before they've sprouted but it doesn't hurt at that point.

Also, the light gives off some heat which is always helpful for the little guys!

How Long Should the Grow Light Be On?

How long do new seedlings need light? For the first three to four weeks, leave the light on for at least 18 hours.

After the first month you can decrease light exposure to 10-14 hours a day. Plants that need a lot of direct sun like peppers and tomatoes should be on the higher end of that spectrum. Plants that prefer a little less light can get by with closer to 10 hours or even 8 hours.

Light Timer

If you bought an LED light with a timing feature it's easy to set to ensure your new plants get the right amount of light every day.

If your light doesn't have a timer, you can buy an outlet timer that will turn power on and off on a schedule.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2019 Katy Medium