Copy and paste this url:
http://www.geocities.com/womplex_oo1/AgriculturalLights.pdf

It is an examination of the radiation spectra for everything from sunlight in LEO and at ground level, to artificial lights (quite a variety too). Nothing is exact, but I trust these numbers since I did it myself.

Visible light consists of radiation from 400-700 nm wavelengths. I integrated across the spectrum from 10-100,000 nm and discovered that visible light is only about 49% of the total energy density of sunlight. The spectrum does not change significantly whether you are in LEO or on the ground, it is just attenuated, or made less intense, and this seems to affect nearly all wavelengths by the same amount. Incidentally sunlight in a greenhouse is only about 1/2 as intense as out in the open, but my calculations were only for sunlight out in the open.

As for the total energy density I have seen various estimates from 1350 - 1380 watts/sq.meter. I've never seen an estimate over 1400 w/m2 but it may depend on a lot of things, in spite of there being no atmosphere in LEO.

Sometimes you see solar resource maps of the USA for the use of photovoltaics. I have come to the conclusion that these maps are not useful for estimating solar energy availability for agriculture. The reason is that photovoltaic cells absorb a different range of wavelengths than plants. Their absorption spectrum is completely different. I went with a straight solar spectrum and integrated it. It was a pleasant surprise when the result came out as 1366 watts per square meter, very close to what I've seen, for example, from meteorological solar irradiance maps.

Much of what I've studied says that there is negligible difference between the solar spectrum in LEO and the solar spectrum at ground level. It is simply attenuated by the atmosphere. So for ground level you get about 250 watts/m2 total radiation, and 125 watts/m2 visible radiation, roughly. The former is about 18% of the 1366 watts/m2 for low-earth orbit.

UV is mostly blocked by the ozone layer, but most of sunlight is visible and infrared. UV is only a very small fraction of the total solar spectrum energy density. Of course you don't need very much UV to get a sunburn. In space we can use simple filters to block UV and infrared. Only visible light that plants use would be allowed into the greenhouse.