What to Look for in a Greenhouse Lighting Supplier: The 8-Point Checklist I Run Before Every PO

Who this checklist is for

If you're sourcing grow lights or commercial fixtures at any real volume — a container order, a multi-site greenhouse retrofit, a private-label ceiling light program — this is the sequence I use before a purchase order gets signed. It's written for procurement people, brand owners, and facility managers who don't have a lighting engineer on staff and don't want to become one.

Eight checks. The desk work takes maybe 45 minutes. The rest depends on how long the sample sits in your rack.

Quick context on where I'm coming from: I'm the quality and brand compliance manager at a commercial lighting company. I review every fixture, spec sheet, and OEM sample before it reaches a customer — roughly 200 line items a quarter, and I've been doing a version of this since 2021. I've rejected about 20 percent of first-article deliveries in that time. Not because suppliers are dishonest. Mostly because nobody wrote down what 'correct' meant.

The 8 checks

1. Ask for the test report, not the spec sheet

Every supplier has a spec sheet. What you want is the underlying IES LM-79 test report — the approved method for electrical and photometric measurement of solid-state lighting. It's the document that tells you the PPF, efficacy, and power draw numbers were measured, not estimated from a component datasheet.

Take a fixture like the Gavita Pro 1700e Gen2 LED. The number in the model name maps to its PPF class in micromoles per second — not to wattage, which is where a lot of buyers get tripped up comparing quotes. Confirm the exact figure on the current datasheet, because revisions happen and marketing names don't always keep pace with engineering changes.

What to actually check in the report: the fixture serial or model it was run on, the date, the lab, and whether the tested unit matches the configuration you're buying. I've seen quotes built on a report for a different driver revision. It looked fine until it wasn't.

2. Get the driver and component BOM in writing

Two fixtures can have identical bodies, identical diodes, and completely different service lives depending on the driver. Same goes for the thermal interface material and the gaskets.

Ask for the bill of materials with manufacturer part numbers. Then ask what happens if a component goes end-of-life. If the answer is 'we'd substitute an equivalent,' your next question is who defines equivalent, and can they do it without telling you.

Here's something distributors won't tell you: the fixture on the quote and the fixture in production are often two different revisions. The BOM clause is what closes that gap — and it's the one most buyers never ask for.

3. Verify the compliance file — and check the edition

For horticultural fixtures, UL 8800 is the standard specifically covering this equipment category, alongside your regional equivalents. For LED packages and long-term output claims, LM-80 test data supports the TM-21 extrapolation that shows projected maintenance over time. IP ratings should be traceable to IEC 60529 testing — an 'IP65' sticker with no report behind it is just a sticker.

Two things people miss here:

• Which edition or version. Standards get revised. A certificate from four years ago may not reflect what's current. Ask for the certificate number and look it up yourself rather than trusting a PDF.
• Where the listing applies. A fixture listed for damp locations isn't the same as one rated for wet, high-humidity greenhouse conditions. Read the actual rating, not the marketing copy.

Also worth knowing: if any of your customers or their projects depend on utility rebates, DLC listing status matters. Check which version of the DLC horticultural technical requirements is currently in effect and whether the specific model is on the qualified list. Verify it at the source — lists change quarterly.

4. Pin down the warranty terms, including what voids them

Warranty length is the easy part. The interesting part is the exclusions. Common void triggers: operating above a stated ambient temperature, non-approved dimming controls, surge conditions above a specified threshold, and mounting orientation outside the listed range.

If you're a distributor, ask a second question: who holds the warranty — the factory, or you? Because if the answer is 'you,' that's a line item on your balance sheet, not a supplier relationship.

5. Test the OEM and private-label capability, not the promise

Plenty of factories will say they do ceiling light OEM. Fewer can show you the process.

What I ask for: a label artwork proof with your mark at production size, a carton drop test result, and a sample of the retail packaging if there is any. For private-label programs specifically, I want to see how they handle the transition from your approved sample to the first mass-production run — because that's where brand damage happens.

The failure in March 2023 changed how I think about sample approval. We'd signed off on a fixture with a specific lens texture. The first production run shipped with a slightly different one. Visually close. Measurably different in distribution. Nobody had written the lens spec into the contract, so legally we had nothing. We ate it.

Now every OEM agreement I touch has a golden sample — sealed, dated, initialed by both sides, held by both sides.

6. Sample the production unit, not the engineering unit

Ask this directly: is the sample you're sending me from the pilot line or pulled off the production line? The difference matters more than people expect. Pilot builds get extra attention.

When the sample arrives, run it at your actual mounting height and measure PPFD at the canopy plane. Don't accept a coverage-area number unless it comes with the mounting height and the PPFD target it was calculated against. Coverage without a target is just a shape.

7. Lock the change-control clause

This is the one most buyers skip, and it's the one that saves the most money.

Your contract needs a sentence that says: no change to any component, material, or process affecting form, fit, function, or photometric output without written approval from the buyer, with a defined notice period. Then define what counts as approval — a signed ECN, not a phone call.

I knew I should have put that in writing on a 50,000-unit annual order back in 2022. Thought it was overkill for a supplier we'd used for years. It wasn't overkill. That quality issue cost us a $22,000 redo and pushed a launch by six weeks.

8. Find out who actually does service

Before you sign, answer three questions:

1. Where does an RMA physically ship to — domestic or back to origin?
2. Who stocks spare drivers and boards, and for how long?
3. What's the advance-replacement policy for a failed unit in a commercial install?

A greenhouse lighting distributor relationship lives or dies on this. If your customers are running production crops, a six-week RMA cycle isn't a warranty — it's a gap in their light schedule. I'd rather spend 10 extra minutes vetting this than deal with mismatch expectations later.

Notes and common mistakes

A few things I'd flag if we were reviewing a quote together:

Don't skip the sample step because the spec sheet looks good. Paper doesn't ship. I've approved maybe a hundred quotes on paper that would have failed a rack test.

Don't treat price as the signal. To be fair, budget vendors occasionally match premium quality, and I get why procurement chases the lowest landed cost — budgets are real. But if a quote comes in well under everyone else, the delta is somewhere. Find out where before you find out in the field.

Don't assume the first article is the production standard. It's the reference. The contract is what makes it stick.

Granted, this is more process than most buyers want on a mid-size order. You can compress steps 2 and 4 into a single BOM-and-warranty email. But steps 6 and 7, I wouldn't skip at any volume. Those two are where the expensive problems live.

And nothing here is a knock on legacy HPS or CMH systems — that's a different decision with its own tradeoffs, and plenty of facilities run them well. This checklist is about making sure you get exactly what you specified, whichever technology you land on.