Fluorescent vs. LED for Seed Starting
Like Velcro, cordless tools and wireless technology, innovations as a result of research by the National Aeronautics and Space Agency have unquestionably changed the habits of daily life. These technological advances extend even to gardening, and investigations into plant growth under light-emitting diodes, or LEDs, may permanently change the way plants are started and grown indoors. Though fluorescents have long been the standard light source for starting seeds indoors, LEDs have a number of advantages that may eventually make the use of fluorescents for plant growing as obsolete as the telegraph.
Take a look at almost any electronic device — it probably has an LED somewhere on it, usually to indicate that the device has power. Though these indicator lights are intentionally dim, recent strides in LED technology have resulted in more powerful lights that are gaining traction for use in general lighting as well as for specific uses like plant growing. Unlike fluorescents, which emit light in a broad spectrum, LEDs are designed to emit light in narrow bands, which can be combined to achieve particular effects. Long-lived, extremely efficient and producing little to no heat, LEDs reduce the power bill, rarely need replacing, do not break easily and virtually eliminate the need to provide extra ventilation or airflow above plants to cool them. Although still more expensive than fluorescents, new LED products developed specifically for plant growing can be plugged right into the wall and linked as needed to form a chain or series of lights.
Factors for Plant Growth
One disadvantage to LED grow lights is their psychedelic appearance. Since plants use only blue and red wavelengths of light for photosynthesis and growth, LED grow lights use combinations of blue and red bulbs that result in an intense purplish glow. Much of the research to date indicates that these blue and red LEDs result in stronger, more vigorous plant growth compared to fluorescent bulbs over the same time. However, because LEDs are designed to emit light in a very specific wavelength, and not all blue-red LEDs produce an equal amount and quality of light, research continues on how different species of plants germinate and perform under different types of LEDs. Early adopters of the technology will probably find that better products will become available as research progresses.
Affordable, practical and widely available for most home growers is the traditional fluorescent tube. For years, the standard advice to indoor growers and seed-starters has been to use a fluorescent fixture with one cool-light and one warm-light tube, suspended several inches above the tops of plants. Full-sunlight spectrum bulbs produce the proper range of light wavelengths, but are less energy efficient and produce heat that can cause young plants to grow too rapidly and become spindly and weak. Bulbs need replacing every year or two, as older bulbs produce a degraded quality of light. Although a fluorescent light apparatus can look clunky and unattractive, the human eye perceives the emitted light as white, making it easier to live with in the home.
Not all seeds require light as a condition for germination. Some species need dark for proper germination, such as annuals like larkspur (Consolida species). Research is still mixed as to whether LEDs or fluorescents are better for seed germination; some research at Michigan State University suggests that seed germination rates are better under LEDs, while other studies done at Wofford College in South Carolina indicate that no difference exists in germination rates between plants started under LEDs and fluorescents, and that fluorescents may actually spur better early root development than LEDs.
Fluorescent vs. LED for Seed Starting. Like Velcro, cordless tools and wireless technology, innovations as a result of research by the National Aeronautics and Space Agency have unquestionably changed the habits of daily life. These technological advances extend even to gardening, and investigations into plant growth …
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 new plants!
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 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 and you can’t control it.
Even if you got your seeds to sprout and they seem healthy, they probably didn’t grow to maturity. This is because they spend all their energy growing towards the sun instead of developing. They burn themselves out before they can 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.
LED Grow Lights for Seedlings
LEDs are a great option for grow lights. They are a bit more energy efficient than fluorescent and there’s a lot of options out there. You’ll find two main types: free-standing and a traditional hanging light.
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 hearty 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.
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.
Grow lights make germinating seeds so much easier indoors! Learn how to use an LED grow light to get your garden started.