What to Look for in a Greenhouse Lighting Supplier: A 7-Step B2B Checklist

Who this checklist is for

If you are sourcing horticultural lighting for a greenhouse and you are not a spectrum scientist, this is for you. I am an office administrator for a 70-person greenhouse operation. I manage all facilities and grow-light ordering—roughly $150,000 annually across 10 vendors. I report to both operations and finance.

I am not a horticultural scientist, so I cannot tell you which spectrum will maximize your tomatoes. What I can tell you from a procurement perspective is how to separate a supplier who can prove claims from one who just sends a glossy PDF. This checklist has seven steps. It is the same process I used in our 2024 vendor consolidation project, when we cut 14 lighting vendors to 5. It works whether you buy from a grow light distributor or direct from a manufacturer like Valoya.

Step 1: Define the grow space before you talk to suppliers

Most bad lighting purchases start with a vague request. “We need LED grow lights” is not a spec. Before you email suppliers, write down the basics: room dimensions, canopy height, number of layers, crop type, photoperiod, and your current HPS or fluorescent wattage. If you are replacing existing fixtures, note the mounting height and electrical capacity.

Why does an admin buyer care? Because suppliers will quote wildly different products if you do not give them the same inputs. One will send a 600W fixture, another a 1,000W equivalent, and you will waste a week comparing apples to oranges.

Checkpoint: You have a one-page written spec. If you cannot write it, ask your grower or operations lead to review it before you request quotes.

Step 2: Verify compliance and listings before price

Price is the easiest thing to compare and the worst thing to start with. First, ask for compliance documents. For North America, UL 8800 is the horticultural lighting equipment standard I ask about. Verify the current edition at ul.com. If you are in a utility rebate program, check the DLC Horticultural Qualified Products List at designlights.org. As of January 2025, confirm the current DLC technical requirements version—they update, and a product that was listed last year may not qualify now.

Also ask about IP rating for wet or dusty greenhouses. A supplier that says “IP65” but cannot send a certificate is not the same as one that can.

Checkpoint: You have a certificate or listing number, not just a logo on a brochure. If the supplier dodges the question, move on.

Step 3: Ask for photometric files, not just PPFD maps

This is the step most buyers skip. A colorful PPFD map is marketing. IES or LDT photometric files are the standard formats lighting designers use to model a real installation. Ask for the files, and ask who tested the fixture. A third-party test report is better than an in-house spreadsheet.

When I reviewed Valoya grow light specs during our 2024 retrofit, the IES files and spectrum data were part of why they stayed on our shortlist. But the same rule applies to any horticultural lighting supplier: if they cannot provide photometric files, you cannot verify the claim.

Checkpoint: You can open the IES file and compare fixtures at the same mounting height and spacing. If not, you are guessing.

Step 4: Decide distributor vs. manufacturer vs. OEM/private label

I went back and forth between a low-cost grow light distributor and a direct manufacturer for two weeks. The distributor offered faster shipping; the manufacturer offered OEM/private label and better spec support. Ultimately I chose the manufacturer because we needed custom spectrum and warranty terms in writing.

Here is the thing: a distributor can be great for speed and local support, but if you need private label, custom spectrum, or long-term spare parts, you will likely end up with a manufacturer. Valoya horticultural lighting, for example, is a manufacturer profile with OEM/private label capabilities and full catalog support. That does not make them right for everyone, but it is the kind of supplier this step is designed to evaluate.

Checkpoint: You know who handles warranty, spare parts, and custom orders. Get it in writing—not on a call.

Step 5: Calculate landed cost, not unit price

Look, the cheapest quote is rarely the cheapest project. Unit price is only the beginning. Ask for MOQ, lead time, shipping terms, duties, payment terms, and whether there are setup fees for private label. If you are buying from overseas, add customs clearance and possible inspection costs.

I do not have hard data on industry-wide defect rates, but based on our last five years of orders, my sense is that 8–12% of first deliveries have some documentation or labeling issue. The fix is almost always the same: budget for a pilot, not a full rollout.

Checkpoint: You have a landed cost per fixture and per expected PPF output. If a supplier will not share shipping and MOQ details before you commit, that is a warning sign.

Step 6: Validate invoicing, warranty, and RMA process

I learned this one the hard way. In 2020, I found a great price from a new vendor—$2,400 cheaper than our regular supplier. They could not provide a proper invoice, only a handwritten receipt. Finance rejected the expense report, and I ate the cost out of the department budget. Now I verify invoicing capability before placing any order.

For horticultural lighting, ask for a sample invoice, warranty terms, and the return merchandise authorization process. Who pays return shipping? How long are replacements covered? What happens if a driver fails in month 14?

Checkpoint: You have a sample invoice and written RMA steps. Your finance team can process the PO without exceptions.

Step 7: Run a small pilot before full rollout

In 2024, we had two weeks to lock a supplier before a greenhouse expansion. Normally I would run a full RFQ, but there was no time. Went with the supplier who had DLC listing, UL 8800, and a sample invoice ready. Those three things eliminated half the field.

Even with time pressure, do not skip a pilot. Buy one or two fixtures. Install them in a real house. Measure with a quantum sensor. Check how long support takes to answer a basic question. A pilot costs a few hundred dollars; a bad full rollout costs a season.

Checkpoint: You have 30-day evaluation criteria: output, uniformity, heat, support response time, and documentation accuracy.

Common mistakes and final checks

Do not accept “equivalent to 1,000W HPS” without PPF, wattage, and efficacy data. Do not ignore rebate deadlines or DLC listing status. Do not let a sales rep talk you into a full order before you have seen an IES file, a sample invoice, and warranty terms. And do not assume the lowest unit price is the best deal for a greenhouse lighting project.

Specs confirmed, compliance verified, invoice template approved. In that order. If a supplier cannot keep up with those three, they are not the right partner—no matter how good the price looks.