Grow lights are often one of the most confusing topics for the beginner gardener. Whether you are looking to start seeds indoors, or keep your houseplants happy over the winter, there are many options to choose from.
In this article, I will go over the different types of grow lights available on the market. This is a simple guide for beginners to ensure you pick the best grow light for your needs. There are budget options available, as well as more expensive set-ups.
When it comes to grow lights, there is a deep rabbit hole you can go down. You can get quite geeky and learn a lot about how these lights work for growing plants. However, this guide is intended to simplify the decision-making process for beginners.
Types Of Grow Lights
When searching for the best grow light for your plants, you’ll see right away there are many different types to choose from. Each type of light has a best use case. Here is a basic breakdown of each light and the best uses for them in the home setting.
1. LED Lights
We use LED lights for starting our seeds and keeping our indoor plants alive when there is not adequate sunlight.
- Long lasting
- Low heat
- Very versatile
- Wide spectrum of light for all growing stages
- Higher initial cost
- Low-quality components can lead to poor longevity
Best Use: We use LED lights for starting vegetable seeds indoors as well as keeping our houseplants alive in low-light areas of the home. LEDs are our preferred type of grow light.
2. Fluorescent Grow Lights
Fluorescent lights can be used as an alternative to LEDs for growing young plants inside. They are fairly efficient, but have less longevity in most cases.
- Runs cool
- Natural lighting
- Less energy efficient than LEDs
- Can be expensive to buy
- Shorter lifespan of the bulbs
Best Use: Suitable for smaller set-ups without many flowering plants.
Which to buy: Vivosun also has a fluorescent grow light option.
3. High Intensity Discharge (HID)
This category of grow lights includes Metal Halide (MH) and High-Pressure Sodium (HPS) lights. They are popular with experienced and advanced growers due to their powerful light output and proven track record.
MH lights emit a blue spectrum (ideal for vegetative growth), while HPS lights produce a red spectrum (ideal for fruiting and flowering). Some growers switch between the two to support each stage of growth.
- Lower upfront cost than LEDs
- Good light output for plant growth
- Generate a lot of heat
- More maintenance
- Requires a more complex set-up
- Not as energy efficient.
Best Use: Good for large-scale operations or advanced growers.
Color Temperature Of Grow Lights For Indoor Gardening
When researching grow lights, it’s easy to get overwhelmed with all the information. There are a lot of numbers and letters involved.
What does K mean on grow lights?
The color temperature of grow lights is measured in Kelvin. Typically, grow lights range from 3000K-6500K. The lower the number is, the more red the light will appear to our eyes. The higher the number, the more blue the light will appear. Kelvin relates to the temperature of the light and how the color looks to the human eye.
In general, higher Kelvin lights are best for growing seedlings and leafy greens. Lower Kelvin lights are better if you plan to grow your plants through the fruiting stage.
What does nm mean on grow lights?
In reference to grow lights, “nm” stands for nanometers, which is a unit of measurement describing the wavelength of light. Different wavelengths correspond to different colors of lights. Plants use different wavelengths of light for various growth processes, so you will want a grow light that covers a wide range of wavelengths (full-spectrum).
- Blue spectrum (450-500nm): promotes healthy foliage in vegetative stage of growth
- Red spectrum (640-700nm): best for flowering and fruiting, encourages blooming and fruit production
When shopping for a grow light, we suggest looking for a full-spectrum light that covers both blue and red.
Do I need a full-spectrum grow light?
Full-spectrum grow lights mimic the natural sun and provide all the necessary wavelengths for plant growth. If you are looking to start vegetable seeds and grow the plants to maturity, you will need a full-spectrum light.
PPF and PPFD
When look at grow lights, you may also see ratings for PPF (photosynthetic photon flux) and PPFD (photosynthetic photon flux density).
PPF – Measures the amount of usable light produced by the grow light in all directions.
PPFD – Measures how much of the usable light is actually reaching the plant growing area. In essence, this measures how efficient the grow light is at providing light that is usable by your plants.
As an analogy, if you were measuring rainfall, the PPF would be the total amount of rain produced by a cloud, and the PPFD would be how much rain is falling on one specific area.
When searching for a grow light to purchase, we recommend buying from a manufacturer who provides PPF and PPFD specifications. Some listings will show a PPFD map which illustrates how the light is distributed across the growing area at various hanging heights.
How High To Hang Grow Lights
This is one of the most common questions we are asked. How high should I hang my grow lights? The answer to this depends on the type of grow light you are using, as well as the type of plant. Luckily, when you purchase a grow light, there are often detailed instructions illustrating the optimal height for hanging.
Every manufacturer is different – so it is best to start off with the manufacturers recommendations when deciding where to hang your grow lights. We suggest starting here, and then adjusting as you go.
In general, LED grow lights are hung between 12-24 inches above the plant foliage, while fluorescent lights are placed closer, around 3-6 inches. Again, this can vary based on the power of the light, and type of plant.
- Is your grow light too close to your plants? If your grow light is too close to your seedlings, you may notice the leaves curling up into a taco shape.
- Is your grow light too far from your plants? A grow light positioned too far from your plants will result in leggy plants that appear to be “reaching” for the light.
The last thing to consider when purchasing grow lights is the coverage area. Grow lights come in many different sizes and forms, so you will want to find one that will work for the space you are growing in.
The coverage area will vary depending on the manufacturer and the height of the light. For example, a light designed for a 2×2 foot area can be stretched to cover a 3×3 foot area by raising the light. However, the intensity of the light will decrease with distance.
Features To Look For
We have years of experience using a wide variety of grow lights, and some features are more useful than others. Here are some of the best features I look for when shopping for a grow light:
- Dimmer knob – I like when a grow light has an adjustable dimmer knob. This allows for more control over the amount of light leading to better efficiency, especially when plants are young.
- Ratchets for hanging – Hanging grow lights can be a pain. When a light has built in ratchets, it makes it a lot easier to adjust the hanging height as needed.
- Heatsink – A heatsink helps to keep the LED lights cooler, increasing the longevity of the light.
- Water resistance – Some grow lights have a water resistant coating over the diodes which is especially useful when humidity levels are high or there is a risk of splashing.
I hope this article helps you feel more confident when looking for a grow light. If you find the right light for your budget, it can last you for many years.