Searching for the best grow lights for seed starting? The market gives you more options than it did at any time in history. Internet is flooded with ‘advice’ on how to choose the best grow lights for seed starting. And yet, you’re here, looking for actionable guidance.
We aren’t saying that you are lazy — quite the opposite. We’re marking you out as someone who is confused. And you have every reason to. The wealth of options has made selecting that one set of grow lights that is right for their plants almost impossible for dozens of farmers.
That’s why we’ve come up with this article. In the paragraphs that follow, we’re going to give you tips to choose the best grow lights for seed starting. We’ll also answer the common questions you may have about indoor grow lights. Let’s get started.
Why do you need grow lights for seed starting?
With the right set of grow lights, you can get stocky, green seedlings. Flowers, vegetables, and herb seedlings require a lot of bright light and can get long and leggy when they don’t get it. That is something you can avoid by giving them the light they need for photosynthesis.
You need grow lights even if you put your seedlings in south-facing windows. These windows won’t provide the intensity (light inside a window isn’t nearly as robust as the sunlight out in the open) or the hours (the sun sets early in early spring/late winter) of lights your seeds need.
On top of everything else, grow lights promote robust and upright growth by providing light from directly above your seedlings. That is something that your seeds won’t get from a windowsill, which will allow the light to fall on your houseplants from the side.
What seedlings need a grow light?
Most vegetable and flower seedlings, warm-season annual crops like pepper plants or tomatoes, and hemp need a grow light for robust growth. All these guys will benefit from artificial light indoors, regardless of how naturally bright your grow area is.
Other plants that love bright artificial light include Monstera, Ficus, Spider Plants, Prayer Plant, Parlor Palm, and Alocasia. These guys will undergo robust growth under a grow light hanging above their hands, but they won’t survive in the event of direct sun contact.
Without adequate grow light, all these seedlings will grow super tall (and thin) in search of more light. Indoor farmers refer to this state of plants as ‘leggy’. Taller seedlings are susceptible to breaking and toppling because they’re weaker than their shorter, stockier counterparts.
What color light is best for seedlings?
Blue color light is best for seedlings. Blue color light has a color temperature range from 5000K to 6500K and has wavelength in the 400 to 520 nanometer range. It helps stimulate the secondary pigments deep inside leaves that are responsible for giving the plant its color and fragrance.
Seedlings also need blue light for the opening of their stomata, the tiny openings on their leaves that control the update of carbon dioxide and water loss. It is therefore necessary that your indoor lighting includes blue in the spectrum.
How can you tell if your seedlings aren’t getting enough blue light? Their leaves will start losing the green color and the plants will start getting leggy. You can tell just by looking at them that the plants aren’t able to hit their growth potential.
Pro Tip: While blue light is indeed helpful for seedlings, red light should take the baton when plants enter the baton stage. Too much of blue light from this stage onwards will leave your plants smaller and thinner than they would otherwise be
What lights are best for seed starting?
Both the LED and T5 Fluorescent grow lights are the best for seed starting. Both are bright enough to give your houseplants the intensity of light they need for robust growth. Having said that, both LED and T5 fluorescent lights suffer from a few shortcomings too.
Here’s a brief comparison of LED vs Fluorescent lights:
LED Grow Light Bulb
LED grow light bulbs are incredibly energy efficient. The United States Energy Department has estimated that, when compared with incandescent bulbs, LEDs use 75% less energy. That is despite the fact that these light bulbs last 25 times longer than their incandescent counterparts.
Much to the delight of your seeds, LEDs will emit very little heat, posing little to zero risk of burning plants nearby. An estimate puts the LEDs heat generation at 5% of their energy, compared with 80% of the energy that CFLs release in the form of heat. That figure is a whopping 90% for incandescent bulbs.
Aside from that, LED light bulbs have the lowest running cost of all light sources. The US Energy Department has estimated that when kept running for 2 hours a day for a whole year, LEDs annual energy consumption cost was $1, much less than that of fluorescent bulbs.
What are the best LED lights for seed starting?
The best LED lights for seed starting usually emit cool (blue-colored) light. Experts tell us that plants need blue color when they are in their foliage, seeding and vegetative growth stage. LED lights with color temperature between 5000K (Kelvin) and 6400K emit blue-colored light.
How close should LED lights be to seedlings?
Provided you choose LED grow lights for your seedlings, a rule of thumb is to hang them somewhere between 12’’ and 30’’ from your plants’ top. If your seedlings look leggy, move the LED closer; if they look bleached, move the LED light bulb back until you find the sweet spot.
Fluorescent Grow Light Bulb
Fluorescent light bulbs cannot lay a glove on their LED counterparts as far as their intensity or shelf-life is concerned. LEDs, as stated above, are much brighter and last much longer than fluorescent lights. Though there are a few reasons why fluorescent bulbs might still be the best option for your seeds.
Even though their light intensity cannot compete with that of LEDs, it is more than enough for weak seedlings, especially those in their germination and vegetative growth stage which can’t be exposed to ultra-bright light or else their leaves might end up getting scorched.
The commonly available sizes of fluorescent lights are T12, T8 and T5. The letter ‘T’ stands for tube and the number states the tube’s diameter. The bigger the diameter, or number, the less efficient the light. That’s why T5 fluorescent lights are your best bet for seed starting.
Pros of Fluorescent Grow Lights
Fluorescent light bulbs cannot lay a glove on their LED counterparts as far as their intensity or shelf-life is concerned. LEDs, as stated above, are much brighter and last much longer than fluorescent lights. Though there are a few reasons why fluorescent bulbs might still be the best option for your seeds.
Even though their light intensity cannot compete with that of LEDs, it is more than enough for weak seedlings, especially those in their germination and vegetative growth stage which can’t be exposed to ultra-bright light or else their leaves might end up getting scorched.
The commonly available sizes of fluorescent lights are T12, T8 and T5. The letter ‘T’ stands for tube and the number states the tube’s diameter. The bigger the diameter, or number, the less efficient the light. That’s why T5 fluorescent lights are your best bet for seed starting.
- Cost less upfront than LEDs
- Produce less heat than other light sources
- Offer a wider light spectrum
- Are widely available
Cons of Fluorescent Grow Lights
- Shelf life cannot compete with that of LEDs
What are the best fluorescent for seed starting?
The T5 fluorescent lights are the best for seed starting. These lights are much brighter and super-efficient than with their T8 and T12 counterparts. Aside from that, their reduced width allows them to better focus the light they’re emitting on a specific area.
How close should fluorescent lights be to seedlings?
Things to look for when shopping for grow lights
Once you have decided between LED and fluorescent grow lights, pay attention to several factors including lumens, size of grow light, the light spectrum, wattage, and more. All these factors will be influenced more or less by the size of your indoor garden.
Let’s discuss all these factors in detail.
Lumens
How much light do seedlings need indoors?
About 2000 to 3000 lumens per square foot of your indoor growing space. That means that if you’re growing just one tray of seedlings, you should turn to a grow light emitting 3,000 lumens. You can find every grow light’s lumens rating on its package.
Size of grow light
Size of grow light is directly influenced by two factors: the surface area you want the light to illuminate (in square foot) and the size of the light fixture itself. Secondary factors that influence the size of grow light include number of plants and your lighting set-up.
How big should my grow light be?
Determine the size of your grow space. A rule of thumb states that you need 20W to 40W per square foot. Divide your bulb’s wattage by 20 (i.e. 100/20=5), then divide it by 40 (100/40 =2.5). Both these (2.5W and 5W) are two extremes of your light intensity range.
Light Spectrum
A light spectrum is the range of wavelengths a light source produces. Two ratings determine it: Correlated Color Temperature (CCT) and Color Rendering Index (CRI). The CCT is the light’s color and ranges between cold (blue) and warm (yellow) colors.
CRI, meanwhile, compares your artificial light with visible sunlight, with the artificial light whose wavelengths are the exact same as of natural sunlight receiving a CRI score of 100. Lights with CCT and CRI scores of 5000K to 6500K and 100, respectively, are best for seedlings.
Bulb Vs Stand Setup
How many plants are you going to grow indoors? If the number is <5, go for a single-bulb setup, especially if your plants haven’t passed their vegetative growth stage. But also keep a stand nearby as it will come handy when your plants have grown taller.
There are other benefits, too, of opting for a stand with built-in lights. Depending on the distance you want to maintain between your seedlings and the plant source, the stand will let you increase or decrease the height of the built-in lights.
Frequently Asked Questions
Can grow lights burn plants?
Grow lights can burn plants if they’re hanging too close to the plants’ tops. If you’re using LED lights, make sure the distance between the plant’s top and the light source is not less than 12-inches (at least). However, you can place a fluorescent light as close as 2’’ from the plant’s top.
What color lights do plants grow best in?
Plants in their sprouting, seedling and vegetative stage grow best in blue color lights, while plants in their budding, sprouting and flowering stage grow best in red color lights. Full spectrum LED lights mix both blue and red colors to come handy for all stages of a plant’s growth cycle.
Do LED grow lights need a ballast?
LED grow lights do not need a blast. These lights come with a built-in converter that converts the direct current they receive into light. This is precisely the reason why you can plug LED light bulbs into a fixture and use the light source for growing seedlings indoors