When there’s no sunlight, grow lights can come to the rescue. Whether you’re looking to help during the vegetable growing season or just help your houseplants through the winter, here’s how to find the best lights for growing plants.
During these shorter winters, with less light coming through your windows, you may wonder if your plants are getting what they need to thrive. While this season’s weaker light may be sufficient for some houseplants, others need a boost to keep growing. Still others, such as garden seedlings and flowering plants, may require more intense light than your home provides.
If you’re considering introducing artificial light into your home, here’s what you need to know.
How to tell if your plants need more light?
If your plants thrive in spring and summer but struggle the rest of the year, it may be time to bring supplemental light to your living space. Adding a few hours of light during the winter can rejuvenate indoor plants and maintain overwintering outdoor pots until the next growing season. It can also help some plants bloom and bear fruit.
Since stressed plants can have problems, here are some signs that your plants need more light:
Dead or yellowed leaves.
Smaller than normal leaves.
New pests and diseases.
Growth of tall and long legs.
Variegated plants lose their variegated color.
To address any of the following issues, take an inventory of your plants and find out how much direct and indirect sunlight they need each day. Use a sunlight calculator or app to determine if your space provides enough light for optimal growth. If not, it’s time to consider grow lights.
Grow Light Basics
Grow lights provide plants with the energy they need to convert light into food, but not all grow lights are created equal. To better understand the differences in grow lights on the market today, consider the categories below.
Spectrum: Most plants need a certain color to thrive. While standard grow lights appear clear or white to the naked eye, they are actually composed of multiple colors to varying degrees. This is called “full spectrum” light. This spectrum includes some colors that are especially helpful for indoor plants.
Blue light helps plants produce chlorophyll, the pigment they need to grow. It also helps promote germination and root development in seedlings and seedlings.
Red light regulates plant growth and helps plants bloom and bear fruit.
Green light helps maximize photosynthesis.
Standard full spectrum grow lights will support most plant growth. Some grow lights allow you to adjust the balance of colors, from warm (more red light) to cool (more blue light) colors, according to your plant’s needs.
Color temperature: The Kelvin (K) unit measures the color temperature of an individual light bulb – in other words, will the light emitted appear warm or cool? This becomes important when your grow lights also illuminate your living space. Opting for a slightly warmer color temperature will bring a cozy glow to your space.
Light Intensity: How much light a bulb or fixture provides depends on its intensity. In the case of LEDs, this is usually measured in lumens. The higher the lumens of the bulb, the more light the bulb produces and the brighter it looks.
Other terms you may come across when considering light intensity include:
Watts: A measure of how much energy a light bulb consumes when in use.
Photosynthetic Photon Flux Density (PPFD): A measure of the useful light intensity in a given area.
Color Rendering Index (CRI): A measure of how accurately a light bulb will render colors in a room. A CRI of 0 means that all colors will be displayed as black. A CRI of 100 means the color will appear as if it were in natural sunlight.
Coverage: The last criterion to consider when buying a grow light is how much coverage it will provide. For LEDs, this is usually measured in lumens, lux or foot candles per square meter.
Which bulb type is best?
There are many types of grow lights, ranging in price and lifespan.
- LED: LED or Light Emitting Diode bulbs are the most efficient at producing light and are the most efficient operation of all home grow lights. They last five times longer than many other bulbs, and with prices dropping so much, there’s no reason not to choose them if you’re looking for a long-term, sustainable, and non-toxic option. Choose a full-spectrum LED bulb for your desk lamp or grower, or choose one of the many red and blue combinations available for specific plant needs.
- Compact fluorescent lamps: These bulbs are less efficient than LEDs and therefore cost more to run. While they are less expensive to buy up front, they have a shorter lifespan and contain mercury, which can be released as vapor if broken. If using compact fluorescent lamps, choose full spectrum to meet a wide range of plant needs.
- Halogens: While not the best choice for growing plants, halogens are brighter than standard incandescent bulbs and can meet some of the light requirements of plants. Given that the light they produce is further along the red spectrum, they lack the blue light needed for healthy growth. However, if combined with other types of lamps, they can meet the overall requirements. Remember that halogens can get very hot when activated, so take care to avoid burning and damaging the leaves.
- Incandescent bulbs: Incandescent bulbs are less suitable for growing plants indoors. When opened, they can get quite hot, which means they need to be placed some distance from the plants, which reduces their effectiveness. They also produce light further along the red spectrum. Finally, they are inefficient and more expensive to operate.
How Much Light Do Indoor Plants Need?
With so many plants available, there is no single answer to this question. However, there are some general rules of thumb to follow.
Low-light houseplants: These plants come from shady or understory areas and grow well in north-facing windows or corners. They require little direct sunlight and survive mostly in indirect light throughout the year. These plants need 10-15 watts or about 50-250 lumens per square foot to thrive. They include:
- peace lily
- snake plant
- english ivy
- Medium light indoor plants
These plants are great for east or west facing windows for indirect light. They need 15-20 watts or about 250-1,000 lumens per square foot to thrive.
Medium light plants include:
- rubber factory
- fiddle leaf figs
- asparagus fern
- spider plant
High-light houseplants: In nature, growing in direct sunlight, high-light plants do well on south or southwest-facing windows. They need over 20 watts or over 1,000 lumens per square foot to thrive. Highlight plants include:
- succulent plants
Before buying grow lights, research the requirements of the plants you already have (or plants you wish to grow). Find out what intensity of light they need, how many hours a day they need, and which spectrum they prefer. If your space doesn’t provide enough light, look for grow lights to fill in the gaps.
The Best Grow Lights for Fruiting and Flowering Plants
Choose a full-spectrum bulb with the option to adjust to more of the red spectrum light for flowering and fruiting. Our favorite is the VITA Grow Bulb, which provides 1:4 blue to red light at 3000 Kelvin. For a similar hanging option, try Aspect Hanging Grow Light.
The Best grow lights for seedlings and starts
Anything that normally needs full sun will need 2,000 to 3,000 lumens of light — including seedlings. Opt for full-spectrum bulbs or something skewed toward the blue side of the spectrum. Hang the plant light of your choice as close to your planting tray as possible to prevent leggy growth. LED bulbs are a good choice because they won’t get too hot and burn tender shoots.
The Best Grow Lights for Tropical Houseplants
Standard tropical houseplants require full-spectrum bulbs with a well-balanced green and blue light. Most indoor plants grow well at 20 to 25 watts per square foot, or about 500 lumens per square foot. We love the versatile Uplift planter, which features fully adjustable (and removable) full-spectrum LEDs.
The Best Grow Lights for Indoor Herb Growth
Most herbs need full sun to grow well. While some people may get lucky with south-facing windows, introducing supplemental light almost always boosts herb growth, making plants with fewer legs and more productive plants. Choose a full-spectrum bulb with over 1000 lumens per square foot.
Our favorite indoor herb growing is the wall-mounted Smart Grow frame. It includes a full spectrum LED of 4000 Kelvin and 1480 lumens. Or, if you’re interested in growing edibles year-round, consider a hydroponic grow cabinet.
Tips for Growing Plants with Lights
- Group plants with similar lighting needs together so they can benefit from the same amount of light.
- Buy grow lights that fit your regular fixtures to help keep costs down. Table lamps are suitable for indoor plants. Tube lights are suitable for seedlings and groupings of plants.
- Choose lamps with adjustable intensity and/or spectrum. Alternatively, choose grow lights with a slightly warmer spectrum to create a comfortable ambient light in your home.
- Set your grow lights on timers so your plants get the right amount of light each day. Many grow lights have built-in timers. If they don’t, use plugin timers for consistent, regular lighting.
Installing a grow light in your regular light fixture is the easiest way to bring more light into your home. This includes desk lamps, reading lamps, etc. Grow lights are generally not suitable for ceiling fixtures or wall sconces because they are too far from your plants. Place light fixtures in dark areas of your home or anywhere your plants need light.