I know, this gadget falls under the heading of toy/tool. Indoor grow lights will take many years to pay for themselves. But I do like my homegrown salads. And I can get a jump start on the garden, harvesting lettuce in early April, instead of June, by starting my seeds indoors.
Last week, I started a flat of lettuce, spinach and kale to transplant in March. I started them about a week earlier than in previous years, and am keeping my fingers crossed that I'll have a harvest that much sooner.
Starting most varieties of seeds indoors needs a soil temperature around 70 degrees, and light for the seedlings for about 14 hours per day. Although these are fluorescent tubes, they do give off a small amount of heat. And by positioning the lights close to the soil, there seems to be enough heat for my seeds to germinate. Once I had a couple of seeds sprouted, I set the timer on the light fixture for 14 hours/day.
I pick my toy/tools carefully, as I don't like a lot of junk hanging around the house. As for just how long this grow light will take to pay for itself, I did some figuring. I used to buy all my tomato seedlings each spring, spending between $15 and $18 per season. The grow light set-up was about $150 (less about $20 with an e-coupon). I now start all of my tomato plants from seeds, saving about $15 per season. I also use the grow lights to get one extra planting of leafy greens started and in the ground, saving about $10-15 on buying leafy greens at the produce stand each spring. On top of these savings, I start smaller amounts of other veggies under the lights, too. My guess is this grow light will pay for itself in about 6-8 years. So, while not a great pay-back timeline, at least it's not a hobby that keeps costing me money.