Edible flowers being grown hydroponically under LED lights

Guide to Buying Grow Lights

Picture taken at Farm.One


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When you think that your plants need more light either because they aren’t growing, are looking etiolated (growing erratically, with a stretched out look, and small leaves) or just want better growth, buying additional lightbulbs is a great idea. I even supplement my southwestern light with artificial light to ensure correct growth for my collection of cacti and succulents.


Types of lightbulbs

Here are some details about the two most used and widely available bulbs, LED and Fluorescent, to consider while shopping.

Bulb color and light wavelengths

Plants get the full color spectrum of light from the sun. Different wavelengths or colors are needed in order to encourage flowering and leaf growth. Light color is measured in (K)Kelvin. Lower Kelvin temperatures (3500K and below) will have a warm/red hue which is good for flowering and fruiting. Higher temperature bulbs (5000K or more) will have a blueish hue which is good for leaf growth. The Kelvin amount will be listed either on the packaging or on the small print on the bulb.

Full spectrum or cool white bulbs will be 4100K which are the best if you just want to buy one light. You may also dislike the red/blue hue of many grow lights. Full spectrum are fine for most common houseplants. Most common houseplants are leafy plants which rarely flower. If you need your plant to flower or fruit, you should go with the red/blue lights.



  •  Higher wattage means a brighter bulb
  •  The wattage number is the watts used per hour
  • Make sure the light fixture can support the wattage of the bulb (Fire Hazard)! Usually the max wattage will be labeled somewhere on the fixture.


Lumens = Brightness

Plants need a minimum of 2000 lumens per square foot to grow. 7000 lumens or more is best. If you already have some natural sunlight, you don’t need as many lumens.


How to Setup Bulbs

  •  Place lights 6”-10” away from your plant. The further away, the more broad of a reach your light will have but the less intense the light’s strength will be. If you put a light too close to your plant it could burn if you’re using fluorescents that get hot.
  •  If setting up bulbs near a window, face the lights toward the window so as to not block any natural sunlight.


Some lighting recommendations:

LED grow bulb – Screws into standard bulbs, great for 1-2 plants.

LED light strip – Great for underneath a shelf. You will likely need more than one depending on your circumstance.

LED grow panel – A powerful solution for many plants, and/or for growing with no natural light.

Outlet timer – So you don’t have to remember to turn the lights on and off.


Learn how much light you have based on window direction and how to increase/decrease light – Read our post ‘Everything You Need to Know About Light’