Grow Lights: What Specs Matter (Without Getting Technical) 💡🌱

(Because “buy a grow light” is easy advice… until you’re staring at 47 options and 900 acronyms.)

If you’re growing indoors in winter, seedlings, herbs, lettuce, houseplants, light is usually the make-or-break factor. And the good news is: you don’t need a fancy setup or a plant-science degree.

You just need to know the few specs that actually matter, and ignore the rest of the marketing noise.

𝟏) 𝐁𝐫𝐢𝐠𝐡𝐭𝐧𝐞𝐬𝐬 𝐢𝐬 𝐭𝐡𝐞 𝐛𝐢𝐠 𝐨𝐧𝐞 (𝐥𝐨𝐨𝐤 𝐟𝐨𝐫 “𝐏𝐏𝐅𝐃” 𝐨𝐫 “𝐋𝐮𝐦𝐞𝐧𝐬”… 𝐛𝐮𝐭 𝐝𝐨𝐧’𝐭 𝐬𝐭𝐫𝐞𝐬𝐬)

Here’s the simple truth:

* 𝐌𝐨𝐫𝐞 𝐛𝐫𝐢𝐠𝐡𝐭𝐧𝐞𝐬𝐬 = 𝐬𝐭𝐮𝐫𝐝𝐢𝐞𝐫 𝐩𝐥𝐚𝐧𝐭𝐬

* 𝐍𝐨𝐭 𝐞𝐧𝐨𝐮𝐠𝐡 𝐛𝐫𝐢𝐠𝐡𝐭𝐧𝐞𝐬𝐬 = 𝐥𝐞𝐠𝐠𝐲 𝐬𝐞𝐞𝐝𝐥𝐢𝐧𝐠𝐬 𝐚𝐧𝐝 𝐬𝐚𝐝 𝐡𝐞𝐫𝐛𝐬

𝐈𝐟 𝐭𝐡𝐞 𝐥𝐢𝐬𝐭𝐢𝐧𝐠 𝐬𝐡𝐨𝐰𝐬 𝐏𝐏𝐅𝐃

That’s a plant-focused measure of usable light. If you see it, great.

𝐖𝐡𝐚𝐭 𝐭𝐨 𝐥𝐨𝐨𝐤 𝐟𝐨𝐫 (𝐬𝐢𝐦𝐩𝐥𝐞 𝐭𝐚𝐫𝐠𝐞𝐭𝐬):

* 𝐒𝐞𝐞𝐝 𝐬𝐭𝐚𝐫𝐭𝐢𝐧𝐠 (𝐬𝐭𝐫𝐨𝐧𝐠 𝐬𝐞𝐞𝐝𝐥𝐢𝐧𝐠𝐬): aim for 𝑚𝑜𝑑𝑒𝑟𝑎𝑡𝑒 𝑡𝑜 ℎ𝑖𝑔ℎ PPFD at close distance

* 𝐋𝐞𝐚𝐟𝐲 𝐠𝐫𝐞𝐞𝐧𝐬 + 𝐡𝐞𝐫𝐛𝐬: moderate PPFD works well

* 𝐇𝐨𝐮𝐬𝐞𝐩𝐥𝐚𝐧𝐭𝐬: lower PPFD can be fine

(𝑀𝑜𝑠𝑡 𝑏𝑒𝑔𝑖𝑛𝑛𝑒𝑟-𝑓𝑟𝑖𝑒𝑛𝑑𝑙𝑦 𝑔𝑟𝑜𝑤 𝑙𝑖𝑔ℎ𝑡𝑠 𝑤𝑜𝑛’𝑡 𝑙𝑖𝑠𝑡 𝑃𝑃𝐹𝐷 𝑐𝑙𝑒𝑎𝑟𝑙𝑦, 𝑎𝑛𝑑 𝑡ℎ𝑎𝑡’𝑠 𝑜𝑘𝑎𝑦.)

𝐈𝐟 𝐭𝐡𝐞 𝐥𝐢𝐬𝐭𝐢𝐧𝐠 𝐬𝐡𝐨𝐰𝐬 𝐋𝐮𝐦𝐞𝐧𝐬

Lumens are human-focused brightness, but they can still help.

𝐑𝐮𝐥𝐞 𝐨𝐟 𝐭𝐡𝐮𝐦𝐛:

For a small shelf/seed tray setup, you generally want a light that’s bright enough that it feels “𝐝𝐚𝐲𝐥𝐢𝐠𝐡𝐭 𝐛𝐫𝐢𝐠𝐡𝐭” up close, not a soft lamp glow.

𝟐) “𝐅𝐮𝐥𝐥 𝐒𝐩𝐞𝐜𝐭𝐫𝐮𝐦” 𝐢𝐬 𝐰𝐡𝐚𝐭 𝐲𝐨𝐮 𝐰𝐚𝐧𝐭 (𝐞𝐚𝐬𝐲 𝐜𝐡𝐞𝐜𝐤𝐛𝐨𝐱)

You’ll see all kinds of color claims like purple lights, red/blue lights, pink glow.

For most home growers:

✅ 𝐂𝐡𝐨𝐨𝐬𝐞 “𝐅𝐮𝐥𝐥 𝐒𝐩𝐞𝐜𝐭𝐫𝐮𝐦” 𝐨𝐫 “𝐃𝐚𝐲𝐥𝐢𝐠𝐡𝐭”

It works well, looks better in your home, and is great for herbs/seedlings/greens.

𝐖𝐡𝐚𝐭 𝐭𝐨 𝐢𝐠𝐧𝐨𝐫𝐞: fancy “bloom boosters” unless you’re doing indoor fruiting plants and you know you need it.

𝟑) 𝐂𝐨𝐯𝐞𝐫𝐚𝐠𝐞 𝐚𝐫𝐞𝐚 𝐦𝐚𝐭𝐭𝐞𝐫𝐬 𝐦𝐨𝐫𝐞 𝐭𝐡𝐚𝐧 𝐩𝐞𝐨𝐩𝐥𝐞 𝐭𝐡𝐢𝐧𝐤

A grow light is only effective in the area it actually covers.

Ask yourself:

* Am I lighting one pot?

* A seed tray?

* A whole shelf?

𝐒𝐢𝐦𝐩𝐥𝐞 𝐫𝐮𝐥𝐞:

If you’re lighting a standard seed tray, make sure the light is meant to cover at least that footprint. One small clip-on light often won’t cover a tray evenly.

𝟒) 𝐃𝐢𝐬𝐭𝐚𝐧𝐜𝐞 𝐟𝐫𝐨𝐦 𝐭𝐡𝐞 𝐩𝐥𝐚𝐧𝐭 𝐢𝐬 𝐩𝐚𝐫𝐭 𝐨𝐟 𝐭𝐡𝐞 “𝐬𝐩𝐞𝐜”

This is where most indoor setups go wrong.

Even a good grow light becomes “meh” if it’s too far away.

𝐒𝐢𝐦𝐩𝐥𝐞 𝐠𝐮𝐢𝐝𝐞𝐥𝐢𝐧𝐞𝐬:

* 𝐒𝐞𝐞𝐝𝐥𝐢𝐧𝐠𝐬: keep the light fairly close (often 2–6 inches above the tops, depending on the light)

* 𝐒𝐞𝐞𝐝𝐥𝐢𝐧𝐠𝐬: usually 6–12 inches

* 𝐇𝐨𝐮𝐬𝐞𝐩𝐥𝐚𝐧𝐭𝐬: can be 12–24 inches depending on brightness

𝐒𝐢𝐠𝐧𝐬 𝐢𝐭’𝐬 𝐭𝐨𝐨 𝐟𝐚𝐫:

* stretching/leaning

* pale growth

* weak stems

𝐒𝐢𝐠𝐧𝐬 𝐢𝐭’𝐬 𝐭𝐨𝐨 𝐜𝐥𝐨𝐬𝐞:

* leaf curl

* bleaching/light spots

* crispy edges (less common, but possible)

𝟓) 𝐓𝐢𝐦𝐞𝐫 + 𝐡𝐨𝐮𝐫𝐬/𝐝𝐚𝐲 (𝐭𝐡𝐞 𝐬𝐩𝐞𝐜 𝐧𝐨𝐛𝐨𝐝𝐲 𝐫𝐞𝐚𝐝𝐬)

The best grow light in the world won’t help if it’s only on for 4 hours.

𝐄𝐚𝐬𝐲 𝐢𝐧𝐝𝐨𝐨𝐫 𝐬𝐜𝐡𝐞𝐝𝐮𝐥𝐞:

* 𝐒𝐞𝐞𝐝𝐥𝐢𝐧𝐠𝐬: 14–16 hours/day

* 𝐇𝐞𝐫𝐛𝐬 & 𝐥𝐞𝐚𝐟𝐲 𝐠𝐫𝐞𝐞𝐧𝐬: 12–14 hours/day

* 𝐇𝐨𝐮𝐬𝐞𝐩𝐥𝐚𝐧𝐭𝐬: 8–12 hours/day (depends on plant + existing window light)

𝐏𝐫𝐨 𝐭𝐢𝐩: A built-in timer (or smart plug) is a sanity saver.

𝟔) 𝐏𝐨𝐰𝐞𝐫 (𝐖𝐚𝐭𝐭𝐬) 𝐢𝐬 𝐮𝐬𝐞𝐟𝐮𝐥… 𝐛𝐮𝐭 𝐧𝐨𝐭 𝐭𝐡𝐞 𝐰𝐡𝐨𝐥𝐞 𝐬𝐭𝐨𝐫𝐲

Watts tell you energy use more than plant effectiveness—but in general:

* ultra-low watt lights can be too weak for seedlings unless they’re very close

* stronger lights give you more flexibility with distance and coverage

𝐃𝐨𝐧’𝐭 𝐠𝐞𝐭 𝐭𝐫𝐚𝐩𝐩𝐞𝐝 𝐛𝐲 “𝐞𝐪𝐮𝐢𝐯𝐚𝐥𝐞𝐧𝐭 𝐰𝐚𝐭𝐭𝐬” 𝐦𝐚𝐫𝐤𝐞𝐭𝐢𝐧𝐠. If it says “100W equivalent” but uses 10W, it’s a marketing comparison, not actual power.

𝐀 𝐬𝐢𝐦𝐩𝐥𝐞 “𝐁𝐮𝐲 𝐓𝐡𝐢𝐬, 𝐍𝐨𝐭 𝐓𝐡𝐚𝐭” 𝐜𝐡𝐞𝐚𝐭 𝐬𝐡𝐞𝐞𝐭

✅ 𝐋𝐨𝐨𝐤 𝐟𝐨𝐫:

* Full spectrum / daylight

* Covers your space (tray/shelf)

* Has a timer (or works with one)

* Adjustable height/distance

* Good reviews from seed starters (not just houseplant decor)

🚫 𝐁𝐞 𝐜𝐚𝐮𝐭𝐢𝐨𝐮𝐬 𝐢𝐟:

* It’s mainly marketed as a “desk lamp”

* It doesn’t say coverage area at all

* It’s tiny but claims it covers an entire shelf

𝐐𝐮𝐞𝐬𝐭𝐢𝐨𝐧: What are you trying to grow under a light this winter—seedlings, herbs, leafy greens, or houseplants?

𝐖𝐡𝐚𝐭’𝐬 𝐲𝐨𝐮𝐫 𝐜𝐮𝐫𝐫𝐞𝐧𝐭 𝐬𝐞𝐭𝐮𝐩: windowsill only, one clip light, or a shelf light setup?

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