Great question! It does depend on the specific light. We use a cell phone app called Light Meter that measures lux. We aim for about 20,000 lux at the tips of the seedlings. That’s a LOT of light and you can do less, even 10,000 lux will get you results. When you get above our recommendation, like can happen with very powerful lights, you can get sun burn on your plants!

We do have two (more modern/newer) lights that have integrated UV LED’s. I can’t say as we truly notice a difference between them and our non-UV lights. I’m sure at some level there is a benefit to UV lights, but I’d also suspect it’d be difficult to actually discern. For example, one study of UV I’m aware of indicated a possible 10% improvement to photosynthesis. Does that mean anything to the gardener? I’d argue no. But, if that study had resulted in 10% more plant growth, that’d be a different story. Thanks for the comment!

Hi RJ! Sorry you found our sources inadequate. The difficulty we’d face is “local to whom?” We get readers from Alaska, Canada, northern US, Norway, Sweden and all over the north. It would be difficult at best for us to provide local sources for anything we might recommend, so usually places like Amazon are at least a “more universal” approach. We do always recommend working with and supporting your local nurseries, especially ones that have comprehensive supply. (It’s important for them to stay in business!) Nonetheless, we are a friendly bunch, so if you have a question about where to get a particular thing, we can do our best to point you in the right direction.