The Best Grow Lights for Indoor Plants

Grow light basics

Grow lights give plants the energy they need to convert light into food, but not all grow lights are the same. To better understand the differences in grow lights on the market today, consider the following categories.

Light spectrum

Most plants need a spectrum of color to thrive. Although standard grow lights appear clear or white to the naked eye, they actually consist of multiple colors emitted in varying degrees. This is known as a ‘full spectrum’ light. Contained within that spectrum are some colors especially helpful to indoor plants.

• Blue light helps plants produce chlorophyll, the pigment they need to grow. It also helps encourage germination and root development in young plants and seedlings.
• Red light regulates plant growth and helps plants produce flowers and fruit.
• Green light helps maximize photosynthesis.

A standard, full-spectrum grow light will support most plant growth. Some grow lights allow you to adjust the balance of color from warm (more red light) to cool (more blue light), depending on your plant’s needs.

Color temperature

The unit Kelvin (K) measures the color temperature of individual bulbs–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 give your space a cozy glow.

Light intensity

How much light a bulb or fixture provides depends on its intensity. This is usually measured in lumens in the case of LEDs. The higher the number of lumens of your bulb, the more light that bulb will produce–and the brighter it will appear.

Other terms you may encounter when considering light intensity include:

• Watts: measures how much energy a bulb will consume when in use.
• Photosynthetic Photon Flux Density (PPFD): measures useful light intensity over a given area.
• Lux: measures the amount of lumens emitted per square meter.
• Color rendering index (CRI): measures how accurately a light bulb will render colors in a room. A CRI of 0 means all colors will appear black. A CRI of 100 indicates colors will appear as they would under natural sunlight.

Coverage

A final criteria to consider when buying a grow light is how much coverage it will provide. For LEDs, this is often measured in lumens per square meter, lux or foot-candles.

Related: Top 10 Plants for Removing Indoor Toxins