How to Choose the Right Grow Lights for Indoor Plants
Having a room, or an entire home, with little to no light is a common struggle when trying to own houseplants; however, grow lights allow one to establish a thriving plant collection year-round. Most plants require at least a smidgeon of light to survive as light is food for plants. Grow lights are specifically designed to serve as a substitute for natural sunlight, allowing for photosynthesis and therefore growth, blooms, or even produce.
Types of Plant Grow Lights
LED and fluorescent bulbs both produce full-spectrum light that plants need to grow. There are many plant light kits on the market that include LED or fluorescent bulbs, but an LED system ($46, The Home Depot) offers several advantages that make them the better choice. For starters, although LED bulbs cost more than fluorescents at purchase time, they use half the electricity fluorescents require and last five times longer than the average fluorescent bulb. They also give off less heat and mercury-free LED tubes don't shatter like glass fluorescent tubes, leading to fewer safety hazards.
Grow Bulbs vs. Grow Lights
Grow bulbs are a great option in that it allow you to swap out your “human” bulbs for these plant ones in any of your current light fixtures, ceilings, or lamps. This option is the cheapest but has a few downfalls. These bulbs don’t always offer a full spectrum and, because our light fixtures weren’t specifically designed for plants, you may end up with uneven lighting or difficulty placing the light source at a correct distance.
Grow lights are more expensive but allow for the most plant success. Since they were designed specifically for this purpose, they will provide more even lighting, for multiple plants. Many offer full light spectrum or even the capability to switch between certain colors when targeting certain types of growth. Grow lights can be attached to walls, shelving, underside of cabinets, or in my case, my refrigerator via a magnet!
What light levels do indoor plants require?
Each indoor plant has a different range of light it can handle from the 'minimum for maintenance' where they may stay alive, but may not do much in the way of growth, right up to commercial growth light levels that a grower might use to achieve maximum growth.
In the middle is the 'good growth' level that we aim for with indoor plants, often with the help of a grow light. This guide below includes some of the most popular houseplants and the light levels they require.
What Color Light is Best?
Alright time for some science. The light spectrum ranges from red, orange, yellow, green, blue, and violet. The colors at the far ends are most useful to plants but all colors are absorbed to some extent. When purchasing your grow light, make sure to read the packaging as it will outline what spectrum is provided. Full spectrum is always the best choice or one that offers a mix of red and blue (which is what my light has in the pictures). Different colors serve different purposes which I will outline below.
Blue light (and for the most part violet) is extremely important as it is how our plants get chlorophyll and therefore grow and strengthen their foliage.
Red light is needed for flowering varieties. You must be cautious when using this as too much red light can kill your plant which is why a lot of grow lights offer a mix of both red and blue so your plants are getting all their needs met.
Green and yellow light is said to have minor benefits when it comes to germinating seeds but otherwise is not essential to your plant.
How much do grow lights cost to run?
Watts alone won't tell you how much power a grow light will use, as how energy efficient the light source is also factored into energy use. LED lights are much more energy efficient than other light sources. Some general costs follow to help you get a sense of power use and cost.
One 60-watt bulb left on for 24 hours will cost around 20 cents per day depending on your rates. Used for 8 hours a day, 7 days a week, a 60-watt bulb works out less than 50 cents a week, or around $24 a year.
An oven on medium to high heat, run for one hour, will use around 2, 400 watts, costing you around 60 cents depending on your power rates (all costs used are based on average rates in New Zealand).
A computer used around 3 hours a day, and unplugged when not in use, costs around $50 to $55 over a year.
A 100-watt fridge or freezer costs around $100 a year to run.
How do I Place and Use the Light?
Ideally, your light would be placed above the plants as that simulates sunlight the best and also allows for the most even coverage. I recognize this isn’t always possible, mine is attached to the side of my fridge and lights my plants from the side and top. Incandescent lights need to be at least 24 inches above your plants. Fluorescent has a lower heat signature and can be 12 inches while a LED can be as close as 6 inches. You will have to adjust your light over time as your plant grows. Check regularly to make sure nothing is getting burned. The height of your light placement will affect the length of time you leave it on.
Depending on the time of year and type of plant, the amount of light your plant needs varies. Flowering varieties and vegetables need 12-16 hours of light a day. Remember that a minimum of 8 hours of darkness a day is important too. Nighttime is when a plant breaks down the energy it gets from the light. Most grow lights will have timers set on them. Mine turns on around 7 am and runs for 12 hours every day. If your plants are farther from your light, they will absorb less. So if you have an incandescent bulb, you may need to leave your light on longer than you do with an LED bulb that is 6 inches away.