Growing Food Inside With Grow Lights
How can you use grow lights?
When bringing plants indoors for the winter, many that aren’t going dormant can benefit from supplemental grow lights. Even a typically sunny window doesn’t bring in much light in St. Louis winters. Indoor food-producing plants typically need at least 8 hours of sunlight during the outdoor growing season, which can be complemented with grow lights.
It’s difficult to completely replace sunlight with grow lights, and most plants will not grow in the same way inside as they would outside during the summer. Fortunately, though, grow lights can help keep plants alive through the winter and, often, produce food at a slower rate.
Shelves vs. stands
If you’re growing more than a few plants, consider outfitting a grow light shelf. In my experience, the steel shelves in either 2-foot or 4-foot are the best – they fit standard bulb lengths, have plenty of spaces to use zip ties or s-hooks, and are a mix of functional and… not super ugly. They’re also great for seed starting!
For larger plants like trees, grow light stands or bulbs are ideal. They are often flexible and easily decorated if they don’t fit your aesthetic. Stands are typically only LEDs, while bulbs can be either LEDs or fluorescent. Trees/large plants can be placed directly on the floor or on a plant stand/table, and the stand adjusted.
LEDs vs fluorescents
In terms of plant growth, LEDs tend to have better light output. But they tend to be more expensive and often need to be ordered online. Fluorescents are much easier to find in any old hardware store. Fluorescent bulbs are more easily replaced if they burn out, as opposed to LEDs, where a typical non-electrician or engineer can’t easily repair it. Fluorescents do use more electricity than LEDs, but if you have a small setup, you likely won’t notice a difference between the two on your electricity bill.
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Temperature
Most lights, for any purpose, will list a temperature. Typically a number in the thousands followed by K (like 6500K, or 2200K). This translates to visible color. Lower temperatures are warmer tones, and higher temperatures appear more blue. White is about 4000K.
These different colors can be used to trigger different plant growth: 3500K-4500K (red light) can trigger fruiting and flowering, while 5000K-7000K (blue light) helps with vegetative growth. For general use, aim for a white/blue light for your plants. This applies to both LEDs and fluorescents.
Wattage
While the wattage doesn’t affect plant growth, it can affect your energy bill. Wattage is simply the amount of electricity the light is using. Check with your energy provider to calculate how much each kind of light would cost.
Daylength
Most plants need at least 8 hours of light per day. Grow lights tend to be less powerful than our sun, so I recommend leaving grow lights on for 12-14 hours per day. Plugging the lights into a timer will keep it consistent and make less work for you!
Height of lights
Growing plants too close to the lights can cause burns, but putting them too far below reduces the amount of light that reaches them. A good general rule is no closer than a 10-12”, but up to three feet, depending on the light and plant structure. Seedlings can be much closer: the top can rest about 8-12” away.
Experiment!
You might find something different that works for your setup and your plants. Keep notes on what your plants like/dislike!
