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What grow-light listings exaggerate

The useful lines on a grow-light listing are the watts, the voltage, the fitting or the length, and a distance chart. Almost everything else in the title is advertising.

Equivalent watts are not the bill

A 15 W LED described as "200 W equivalent" or "300 W equivalent" is being compared with an older lamp, usually an incandescent or a blurple panel from a previous generation. The comparison is the maker's, and different makers use different old lamps. You pay for 15 W.

On the October–December 2026 cap average of 26.32 p/kWh, that 15 W bulb for 12 hours is about 4.7 p a day. A genuine 200 W load for 12 hours would be about 63 p a day. The running cost page shows the working. If a title and a rating label disagree, believe the rating label.

Lumens are for eyes

Lumens and lux measure brightness as people see it, weighted towards green. Plants use a different mix. Two lamps with the same lumen number can feed a plant very differently, and a horticultural lamp can look dimmer than a cool-white utility tube while delivering more useful light.

PPFD, at a stated distance, is the plant number. PPF is the lamp's total output. Both are explained, with a DLI example you can recalculate, in PPFD and distance. A listing that quotes PPFD with no distance is unfinished. "High PPFD" with no number is a slogan.

Coverage diagrams that include the hallway

"Covers a 2 × 4 ft tent" can be a real claim for a panel, at a height the maker should state, for a plant that can use light at the edge. "Covers a whole room" on a 10 W clip lamp is not. The edge of a beam is where seedlings stretch. If you need even light on a tray, buy length (a bar) or a panel sized to the tray, and overlap rather than believe the widest number in the title.

The Spider Farmer SF600 listing's own coverage line is 60 cm × 120 cm at 72 W. That is already a bench, not a side table. Read coverage against watts. A huge area on a tiny wattage means the light at the edge is weak.

We haven't tested this kit. Specifications are as the maker states them (checked 13 November 2026).

Spectrum words

"Full spectrum" should mean a white horticultural LED rather than red and blue only. It is not a regulated grade. "Sunlike", "4000 K" and "for all stages" are descriptions, not measurements of your shelf. Blurple versus white, and when the purple is worth tolerating, is in full spectrum and blurple.

The wrong mains, and the wrong room

Confirm 220–240 V, 50 Hz, and a UK plug or a fused adapter. A 120 V fitting is for a different country. E26 and E27 look similar and are not the same cap. The UK screw cap you want is E27, covered in E27 and B22.

If the photographs are all tents, filters and flowering canopies, the product may still be electrically fine and still be the wrong object for a living room. Tent systems are outside this site. Hydroponics Guide is the sister site for that scale.

Reviews of a different size

Packs are often one listing with a 1 ft, 2 ft and 4-pack option. A five-star review for the four-pack does not describe the single tube. Check the size you are actually buying, and the wattage of that size. The shortlist names the size the specification refers to for that reason.

Nothing on this page is a test. If a maker's chart and a review disagree about distance, follow the chart, then watch the plant.