Led lighting is different to any previous kind of lighting, and if we want to maximize its advantages, we must change our way of thinking about light. Leds dont need to work in bulb shape, in fact, its a very bad idea because thermal considerations, especially important for red leds, wich are very temperature sensitive.

We can put the leds arrays very close to plants and between them, because leds dont give heat enough to damage plants and dont radiate IR and UV (if we dont want to). Using led's reflectored bulbs dont make any sense in horticultural applications. Leds bulbs useful life is below 15000h, because quick degradation due to heat.

Hanging leds strings between plants is the way to go, and use medium-low power leds well spaced, in the way there isnt need of cooling. In this way, the led's low intensity isnt a problem.

When I mention efficiency percentages, it refer at % of light emitted (in watts) of total input power (for horticultural applications, PAR light (400-700nm) is counted). Its very difficult compute leds efficiency, because it depends of ambient temperature, thermal resistance (and how dense are the leds packed) and at what current the led is runned, talking about the same led. And differences between leds are very, very large.