Photosynthetic photon flux Ddensity, or PPFD, expressed in micromoles per square meter per second (μmol/m²/s), is a measurement of how much light reaches your plant that’s usable for photosynthesis. In general, the higher the plant’s energy needs, such as producing a flower or a fruit, the higher the PPFD number you want. Though different lights have different height requirements given the plants they’re made for, for standardization purposes, I measured the PPFD of each grow light at 18 inches with the Photone app and a light diffuser. Keep in mind these measurements are general and approximate.
Some of these grow lights I bought myself, with my own money, before I even began working at WIRED. Others were owned by staffers and recommended to me. I also have press samples from other guides I worked on, which I liked so much I ended up keeping around.
For the traditional grow lights, I tested them at home under normal-life conditions. I put them where they’d fit, tested their timers, and noted whether or not they were dimmable. I also measured each light’s PPFD (see above) and noted whether certain lights could be daisy-chained for more extensive coverage.
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Best Grow Light for Small Plants and Seedlings
WIRED
- Slim and unobtrusive
- Controls are right on the light
TIRED
- Must attach to a horizontal surface
- Light only strong enough for small plants
There are a lot of options out there for starting seeds and helping houseplants along in the winter, and many of them are bulky, fussy, or require elaborate hanging setups. This simple, 15-inch-long light from Vego sticks to its 3M adhesive mount with a magnet, so it’s easy to take on and off and use with existing racks or, as I do, under a kitchen cabinet. Up to four Vego lights can be daisy-chained together, and the five preprogrammed modes (Seeds, Leafy, Fruits, Herbs, Microgreens) have varying intensities and automatic built-in off periods to simulate nighttime. I have not found this light especially disruptive, especially since it’s easy to turn on and off with the button on the back.
WIRED commerce SEO director Stewart Savin used these lights to start her garden earlier this year and had 138 successful germinations across 144 seedling cells. (“The vast majority of those plants went on to have long lives in my garden after I hardened them off,” she says.) Note that because this light can only go beneath a rack, shelf, or cabinet, it’s not inherently adjustable, and therefore is best for small plants (like seedlings) that aren’t going to grow especially tall.
Most Versatile Grow Light
LetPot
100-Watt Grow Light
WIRED
- Can hang or sit on included stand
- Easy-grab remote on a cord
- Adjustable
TIRED
- Stand isn’t the most stable
This do-anything light, with a broad 2 x 3-foot head, can hang from the ceiling or swivel on its included stand where you need it. (Up to 20 of these lights can be daisy-chained.) Note that while the stand is useful, the 1-inch-diameter pole and offset base aren’t the sturdiest, and it’s easy to knock over, so I’d recommend hanging it if you have pets and small kids. I learned this the hard way while trying to revive a corn plant in a dark corner at the top of my stairs.
While this light is quite bright and potentially disruptive, it’s easily dimmable via the remote, which hangs on a cord. At first I thought this was weird, but I found it extremely useful when the light was behind plants or in another hard-to-reach spot.