Well exactly - the most efficient way of using the sun's energy to grow plants, is to plant them in dirt in a place where the sun will shine on them. Manufacturing turbines, power distribution infrastructure, hydroponic equipment and fertilizers - it's a massive investment of (mined) materials and (often coal) power.
I mean, it makes sense if you're growing marijuana illegally - the operation is hidden and well fortified, and the extreme markups the War on Some People Who Make and Use Some Drugs makes possible allow you to pay off the extreme inefficiency of the whole operation.
I did some back-of-the-envelope calculations a little while ago, and as far as I can tell, wind energy is effectively 25% fossil fuel, just from mining and smelting materials, and then manufacturing the turbines. Another way of looking at it - over a turbine's 20 year expected life, the first 5 years or so are spent breaking even on the energy expended manufacturing the turbines.